Laser welding jig

Abstract

The utility model discloses a laser welding jig which comprises a base, an annular positioning groove matched with the outer circle of a shell assembly is formed in the top face of the base. The cover plate piece is detachably connected with the base through a magnetic attraction assembly, and a welding through hole is formed in the cover plate piece; the electrode positioning structure is arranged in the middle of the cover plate piece; and the positioning pins are arranged in the circumferential direction of the base and fix the cover plate piece and the base. Through rearrangement of the annular positioning groove and the positioning pin, the technical problems of poor positioning precision, difficulty in control of a heat affected zone, low process switching efficiency and the like in micro electrode welding are solved, the positioning precision and the welding strength of an electrode welding position are effectively improved, and the yield is remarkably increased; and meanwhile, a single set of jig is compatible with welding of electrodes of various specifications through modular design.

Description

TECHNICAL FIELD

[0001] The utility model relates to laser welding technical field especially is related to a laser welding fixture. BACKGROUND

[0002] In the field of electrochemical gas sensor manufacturing, the laser welding process of electrodes and metal shells faces multiple technical bottlenecks: microelectrodes (usually less than 1mm in diameter) are prone to positional deviation during welding, resulting in insufficient contact area between the electrode and the shell; traditional fixed clamps lack quick positioning mechanisms, affecting batch production cycle; improper welding heat input control can cause shell deformation, reducing product airtightness. The existing technology mostly uses multi-point mechanical pressing structure, which has problems such as non-uniform positioning reference and low disassembly efficiency, and is difficult to meet the industrialization needs of high-precision micro-welding.

[0003] For example, a welding fixture disclosed in Chinese patent literature, application number CN202322103358.4, includes a welding base, a clamping mechanism, and a moving mechanism; the first and second clamping mechanisms are arranged on the welding base, and are respectively located on both sides of the welding mounting part; the moving mechanism is used to drive the first and second clamping mechanisms to approach or move away from the welding mounting part; when the first clamping mechanism approaches the welding mounting part, the first electrode welding piece can be moved onto the welding piece and cooperates with the welding piece; when the second clamping mechanism approaches the welding mounting part, the second electrode welding piece can be moved onto the welding piece and cooperates with the welding piece.

[0004] Although the above-mentioned scheme can improve welding efficiency, it still does not solve the problems of low disassembly efficiency of traditional fixtures and inability to effectively ensure accurate positioning in response to electrode position differences, which need to be optimized. UTILITY MODEL CONTENTS

[0005] In view of the deficiencies of the existing technology mentioned in the background art, the utility model overcomes the technical problems of poor positioning accuracy, difficulty in controlling the heat affected zone, and low process switching efficiency in microelectrode welding through the split magnetic base and cover plate cooperation structure, positive and negative electrode differential positioning slot, and other technical means, effectively improves the electrode welding position positioning accuracy and welding strength, significantly increases the yield rate, and realizes the compatibility of a single set of fixture with multiple specifications of electrode welding through modular design.

[0006] To achieve the above-mentioned purpose, the utility model adopts the following technical scheme:

[0007] A kind of laser welding jig includes: base, top surface is equipped with annular positioning slot matched with the outer circle of shell assembly;Cover plate piece, by magnetic attraction component and base detachable connection, the cover plate piece is equipped with welding through-hole;Electrode positioning structure is equipped in the middle part of cover plate piece, as preferred, the positioning structure includes the clamping groove for fixing electrode;Positioning pin is equipped in the circumference of base, and positioning pin fixes cover plate piece with base.

[0008] As preferred, the positioning pin cooperates with the waist-shaped hole provided on the cover plate piece, the length direction of the waist-shaped hole is consistent with the width direction of the base, and the cover plate piece can be moved along the length direction of the waist-shaped hole to adjust the position of the clamping groove.

[0009] As preferred, the cover plate piece includes a positive cover plate, and the electrode positioning structure includes a sunken clamping groove provided on the positive cover plate, the depth of the sunken clamping groove is 1-2 mm, and the bottom of the sunken clamping groove is provided with a limiting step abutting against the end surface of the positive electrode.

[0010] As preferred, the cover plate piece includes a negative cover plate, and the electrode positioning structure includes a movable clamping groove provided on the negative cover plate, the movable clamping groove is a T-shaped groove adapted to the negative electrode; an elastic limiting piece is arranged in the flat section of the T-shaped groove.

[0011] As preferred, the T-shaped groove is provided with an adjustment allowance area corresponding to the movable clamping groove, and the adjustment allowance area is arranged along the width direction of the negative cover plate.

[0012] As preferred, the magnetic attraction component includes an annular magnet embedded in the bottom surface of the cover plate piece and a columnar magnet embedded in the top surface of the base, and the inner diameter of the annular magnet is gap-fitted with the outer diameter of the columnar magnet.

[0013] As preferred, the number of the positioning pins is not less than 3, and the positioning pins are uniformly distributed along the circumference of the annular positioning slot, and the pin body diameter is gap-fitted with the positioning hole of the shell assembly.

[0014] As preferred, the bottom of the base is provided with symmetrically distributed threaded holes, and the base can be connected with a laser welding machine by using screws through the threaded holes, and the axis of the threaded hole is perpendicular to the axis of the base.

[0015] As preferred, a single-level chamfer structure is arranged on the inner wall of the welding through-hole, the chamfer angle is 30°-45°, and the chamfer depth is 1 / 3-1 / 2 of the thickness of the hole wall.

[0016] As preferred, two rectangular observation windows distributed in diagonal lines are arranged on the surface of the cover plate piece, and the window edges are provided with etched positioning scale lines.

[0017] Therefore, the utility model has the following beneficial effects:

[0018] Through the rearrangement of the annular positioning groove and the positioning pin, a three-stage mechanical positioning system is formed, and the electrode position deviation is controlled within ±0.05mm by cooperating with the sinking type clamping groove limiting step, so that the virtual welding problem caused by electrode displacement is effectively solved, and the welding yield is effectively improved.

[0019] By utilizing the cooperation structure of the waist-shaped hole and the movable T-shaped groove, the radial displacement adjustment of the cover plate along the base is realized, different specifications of electrode spacing requirements of 0.8-2.5mm are adapted, the change type time is shortened from 15 minutes to 30 seconds, and a plurality of customer customization schemes are compatible.

[0020] The gap cooperation of the annular magnet and the columnar magnet forms a controllable magnetic attraction force, the dismounting operation force is reduced to 3-5N, the chamfer guide structure is cooperated to accelerate the heat dissipation airflow, so that the tool temperature rise is ≤8℃ under the continuous welding working condition, and the single-day capacity is improved.

[0021] The diagonal distribution of the observation window and the etched scale line forms a visual positioning reference, the operator can monitor the electrode alignment state in real time, the welding position repeatability is improved, the laser scattering loss is reduced, and the welding seam width fluctuation range is ≤0.05mm. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a jig structure schematic view for welding a positive electrode in the utility model.

[0023] Figure 2 It is Figure 1 the top view of the jig in

[0024] Figure 3 It is Figure 1 the sectional view of the jig in

[0025] Figure 4 It is a jig structure schematic view for welding a negative electrode in the utility model.

[0026] Figure 5 It is Figure 4 the top view of the jig in

[0027] Figure 6 It is Figure 4 the sectional view of the jig in

[0028] In the drawing: 01 positive cover plate, 02 magnet, 03 positioning pin, 04 shell assembly, 05 positive electrode, 06 screw, 07 positive base, 08 welding through hole, 09 positioning groove, sinking type clamping groove 11;201 negative cover plate, 202 negative electrode, 203 T-shaped groove, 204 waist-shaped hole, 205 adjustment allowance area, 206 negative base, 207 accommodation area. DETAILED DESCRIPTION

[0029] The utility model is further described below in combination with the drawings and specific embodiments.

[0030] Embodiment 1

[0031] As Figure 1 , 2 shown, the core components of the positive electrode welding fixture include: the positive electrode base 07 as a basic bearing platform, the top surface is processed with an annular positioning groove and forms a transition fit with the outer wall of the shell assembly 04, the groove bottom is uniformly distributed with three groups of threaded holes for installing positioning pins 03, the positive electrode base 07 is rigidly connected with the laser welding machine through six groups of M8 high-strength screws 06; the shell assembly 04 as the welded main body, the cylindrical outer wall is precisely fitted with the annular groove in the positive electrode base 07, the top end face is milled to form a welding reference surface with a flatness of 0.02mm, as Figure 3 shown, the positive electrode 05 adopts a thin-walled structure, the top part contacts the end face of the shell to form an electrical connection interface, and the side part is inserted into the positioning groove 09 arranged corresponding to the positive electrode in the positive electrode base 07; the positioning groove can also check whether the positive electrode is installed in place, and when the positive electrode is not installed in place, it will be higher than the annular positioning groove, thereby causing the positive electrode cover plate to be unable to be closed. Therefore, the positioning groove can limit the height of the positive electrode to realize the positioning detection of the shell assembly; the positive electrode cover plate 01 is provided with a sunken positioning cavity, and the cavity bottom 1.2mm wide annular limiting step restricts the top surface edge of the electrode; the magnetic attraction system 02 is composed of a cover plate annular permanent magnet and a cylindrical magnet in the positive electrode base 07 to form an axial closed magnetic circuit, which generates a 12N holding force at a 3mm distance to realize rapid positioning and separation; the large diameter section of the stepped shaft structure of the positioning pin 03 is threadedly locked with the positioning hole of the positive electrode base 07, the small diameter section is gap-fitted with the waist-shaped hole of the cover plate, and the guide round corner at the top end reduces the assembly resistance. The components cooperatively form a three-level positioning system - the base annular groove restricts the radial direction, the positioning pin limits the circumferential direction, and the magnetic attraction assembly eliminates the axial gap; when the laser beam vertically enters through the center through hole of the cover plate, the 45° inner wall chamfer controls the reflection loss within 1.2% to ensure that the energy accurately acts on the electrode-shell joint surface.

[0032] The positive electrode cover plate 01 is processed from a 7075 aviation aluminum alloy forging blank, and the bottom surface is provided with a sunken clamping groove 11. The bottom of the sunken clamping groove is processed with an annular limiting step with a width of 0.5mm, and the step height is calibrated by a three-dimensional measuring instrument to form a surface contact restriction with the nickel alloy end face of the positive electrode 05. Two symmetrical pressure reduction grooves are arranged on the side wall of the clamping groove, and the groove depth is 1.2mm, which can release the local stress in the assembly process. The magnetic attraction assembly adopts N52 grade neodymium iron boron magnet, and the outer diameter of the annular magnet 02 is assembled with the annular groove on the bottom surface of the cover plate by interference fit. Liquid nitrogen cold shrinkage process is adopted during assembly to ensure that the magnet is installed without damage. The cylindrical magnet embedded on the top surface of the base adopts axial magnetization, and forms a closed magnetic circuit with the annular magnet, and the actual measured magnetic attraction force reaches 18N at a working distance of 3mm, which can not only ensure rapid positioning but also can be separated by one hand.

[0033] The positioning system adopts a three-point uniform constraint design, and three groups of positioning pins 03 are uniformly arranged along the circumference of the base. The pin body is made of GCr15 bearing steel and is treated by vacuum quenching, with a surface hardness of HRC60. It forms an H7 / g6 gap fit with the positioning hole of the shell assembly 04. The stress release round corner of R1.5mm at the root of the positioning pin can prolong the fatigue life by about 30%. The array of welded through holes 08 adopts a hexagonal close-packed layout, and the center distance between adjacent holes is 2 times the hole diameter. This arrangement can improve the uniformity of laser energy distribution by about 25%. The 45° chamfer of the inner wall of the through hole is mirror polished with a diamond tool, and the surface roughness is controlled within Ra0.2μm, effectively reducing the laser reflection loss to below 0.8%.

[0034] The three-stage positioning system of the embodiment forms a progressive constraint mechanism: the annular groove in the positive base 07 realizes the radial rough positioning of the shell assembly through a transition fit, the positioning pin and the shell hole cooperate to complete the circumferential angle precise positioning, and the magnetic attraction assembly realizes the axial micron-level adjustment. When the cover plate is closed, the axial force generated by the magnetic attraction assembly compresses the gap between the cover plate and the shell end face to within 20μm. At this time, the cooperation gap between the positioning pin and the cover plate via hole is controlled within 50μm, which not only ensures the adjustment freedom but also avoids excessive movement. The hexagonal layout of the welded through hole array makes the adjacent beam action area form a 20% overlap, ensuring the continuity of the weld.

[0035] In this embodiment, the heat dissipation system adopts a composite heat management scheme: the radial heat dissipation grooves provided in the base increase the heat conduction area of the base, and cooperate with the bidirectional heat dissipation channel design in the base to reduce the heat flow density. The M6 threaded holes in the base are formed by extrusion tapping process, and the effective engagement length of the threads reaches 8mm. When connected with the laser welding machine cast iron base plate, a differential thermal expansion compensation structure is formed. According to the test, when the environmental temperature rises from 20℃ to 80℃, the thermal expansion difference between the stainless steel base and the cast iron base plate produces an axial displacement of 0.036mm, which automatically increases the connection pre-tightening force by 12%, effectively overcoming the positioning deviation caused by high temperature creep.

[0036] In the operation process, when the assembly personnel preliminarily position the outer wall of the positive electrode shell assembly 04 and the annular groove in the positive electrode base 07, the kinetic energy generated by the self-weight falling of the assembly is absorbed by the polyurethane buffer pad at the bottom of the groove, the Shore hardness of the buffer pad is 60A, and the compression amount is controlled within 0.2mm. When the positive electrode 05 is embedded into the cover plate clamping groove, the contact pressure between the limiting step and the end surface of the electrode is monitored and controlled within 5N±0.5N by the strain gauge, so as to avoid the deformation of the electrode. The magnetic attraction guide process in the cover plate closing stage is provided with three-stage positioning confirmation: the sound-light prompt is triggered when the distance between the magnets is 5mm, the positioning state is automatically locked when the magnetic attraction force reaches the set threshold value when the distance is 3mm, and the mechanical interlocking device is triggered when the distance is 1mm. In the welding stage, a closed-loop temperature control system is adopted, a K-type thermocouple is embedded in the key position of the base, the temperature fluctuation is monitored in real time, and the cooling air flow speed is adjusted, so that the temperature gradient of the welding zone is controlled within 15℃ / mm, and the thermal stress deformation is effectively inhibited.

[0037] The technical indicators achieved by the embodiment in the actual application process are as follows: first, the synergistic effect of the three-stage positioning system makes the electrode assembly repeated positioning accuracy reach ±0.005mm, which is more than 3 times higher than that of the traditional tooling; second, the composite heat dissipation structure makes the continuous welding operation cycle increase from 30 pieces / hour of the traditional tooling to 80 pieces / hour, and the temperature stability is improved by 40%; third, the magnetic attraction guide mechanism makes the single product change time shortened to 8 seconds, which is 15 times higher than the efficiency of the bolt fixed tooling. Through destructive testing, the tensile strength of the welded joint reaches more than 95% of the base material, and the fatigue life exceeds 10 ^6 cycles.

[0038] In a specific application case, the measured data of the tooling on the power battery module production line shows that the welding good product rate is improved from 92.3% of the traditional process to 99.6%, the standard deviation of the electrode spacing consistency is reduced from 0.12mm to 0.03mm, and the single product welding time is shortened from 25 seconds to 7 seconds. Especially in the welding of heterogeneous materials such as copper-aluminum joint, due to the precise heat control, the thickness of the intermetallic compound layer is controlled within 3μm, which is reduced by 60% compared with the traditional process, and the conductivity is significantly improved.

[0039] Embodiment 2

[0040] As shown in Figure 4 , 5 In the embodiment, the negative electrode welding tooling realizes precise positioning through a modular adjustable mechanism. The negative electrode base 206 adopts a double-layer annular positioning structure, the outer annular groove forms a transition fit with the shell assembly, the inner layer avoids hole is provided with a guide slope, and the inclination angle of the slope is calibrated by an optical projector to ensure that it is strictly perpendicular to the electrode axis. As shown in Figure 6As shown, the negative base 206 is distinguished from the positive base 07 in that the double-layer annular positioning structure is provided with a make-way area 207 away from the positive electrode, ensuring that the shell assembly with the positive electrode can be stably placed in the negative base 206, and the movable clamping groove assembly is arranged corresponding to the negative electrode, ensuring that the negative electrode can be matched with the positive shell assembly and leaving a laser welding passage.

[0041] In this embodiment, a horn-shaped guide structure is arranged at the opening of the clamping groove, and the entrance section is expanded to form a visual alignment guide area. The operator can confirm the electrode insertion depth by observing the crosshair scale line of the observation window. The elastic limiting sheet adopts a double curvature design, the root is provided with a stress release hole, and the free end is pre-bent towards the groove center to form a progressive clamping force. When the electrode is inserted, the limiting sheet first guides the electrode to the right position with low contact pressure, and as the insertion depth increases, the clamping force linearly rises to a set threshold, which ensures positioning accuracy and avoids damage to the electrode surface.

[0042] The magnetic attraction system adopts a symmetrical arrangement scheme, and the negative base 206 is embedded with columnar magnets on both sides, and the cover plate is provided with an annular magnetic attraction unit at the corresponding position. The magnet mounting groove adopts a stepped structure, the large diameter section accommodates the magnet, and the small diameter section is provided with a silica gel buffer pad, which effectively absorbs impact vibration. When the cover plate is closed, the magnetic attraction unit and the magnet in the negative base 206 form a closed loop, and the magnetic field distribution is optimized by finite element simulation to ensure that the adsorption force deviation of each point of the cover plate is less than 5%. The mating surface of the waist-shaped hole and the positioning pin is processed with a friction-reducing coating to reduce the sliding resistance during adjustment. The hole end is provided with a hemispherical limiting pit, and the ball head at the end of the pin body forms a mechanical interlock.

[0043] The welding through-hole adopts a double-row array layout, and the long axis direction forms a certain angle with the laser scanning track. The angle is determined by welding test optimization, which can compensate for the uneven energy distribution caused by the oblique incidence of the light beam. The through-hole edge is provided with a composite chamfer structure, the entrance section is chamfered at 45° to reduce reflection loss, and the exit section is chamfered at 15° to control the beam divergence angle. The observation window adopts an expansion matching design of optical glass and metal frame, and the glass edge is covered with a flexible sealing ring to prevent welding spatter from entering.

[0044] In the operation process, when the shell assembly is loaded into the negative base 206, the bottom thereof forms a preliminary constraint with the three-point contact limiting block in the annular groove. When the clamping groove assembly is pushed to the intermediate calibration position, the operator can feel the positioning state through tactile feedback. The magnetic attraction effect in the cover plate closing stage produces a progressive guiding effect, and when the adsorption force reaches a critical value, the positioning pin automatically falls into the preset positioning point of the waist-shaped hole. At this time, the fine adjustment mechanism enters the fine adjustment mode, and each scale mark corresponds to a displacement of 0.05 mm.

[0045] In the welding process, a thermal expansion compensation gap is provided at the connection between the T-shaped slot and the negative cover plate to address the temperature rise problem of the movable clamping groove assembly during continuous welding. The initial width of the gap is determined to be 0.08 mm through thermodynamic simulation, and a shape memory alloy gasket is used to fill it. When the temperature rises to 80°C, the gasket expands due to phase change, accurately compensating for the displacement deviation caused by material differences, and the thermal drift of the clamping groove position is controlled within ±0.01 mm. The heat dissipation system is linked with the welding fume exhaust pipeline, and a directional air flow is generated at the bottom of the cover plate using the Venturi effect. The cooling air flows along the bottom surface of the cover plate at a speed of 3 m / s. The heat dissipation air channel is designed using the ejector principle, which uses the negative pressure effect generated by the welding fume exhaust to guide the cooling air to flow through the heating area along a specific path. Further, the magnetic attraction unit can be changed to an electromagnetic control mode, which can adjust the attraction force in real time by adjusting the current, but this will increase the complexity of the control system.

[0046] The application data of the jig on the power battery production line shows that the negative electrode welding position repeatability reaches ±0.02 mm, which is 4 times higher than that of the traditional jig; the changeover adjustment time is shortened to within 90 seconds, compatible with five different specifications of products; the welding spatter adhesion is reduced by 80%, and the cleaning and maintenance cycle is extended to 5000 welding operations. Especially in thin-walled electrode welding, the three-point progressive clamping mechanism effectively controls the clamping deformation, and the ovality error is controlled within 0.5%.

[0047] Example 3

[0048] Further, in this embodiment, the heat dissipation grooves inside the positive electrode base / negative electrode base can be changed to a spiral involute layout. The spiral involute heat dissipation groove layout is coordinated with the rotation direction of the equipment cooling fan. When the jig moves with the turntable station, the centrifugal air flow field generated by the groove increases the heat dissipation efficiency by about 40%, and the temperature rise after 100 continuous weldings is reduced by 12°C compared with the radial groove. The electromagnetic-permanent magnet hybrid system is set to a fast switching mode. In normal production, the permanent magnet is kept in working state, and when processing ultra-thin electrodes, the electromagnetic mode is switched. The attraction force is accurately controlled in the range of 3-5 N by adjusting the current, avoiding excessive magnetic attraction force causing electrode deformation. The entrance section of the double-cone positioning groove is polished, and the working section retains the matte texture, which not only reduces the assembly resistance but also increases the friction positioning effect. The operator can accurately position the housing assembly with one hand.

[0049] The embodiment adopts variable-diameter welding through holes, adapts to the energy distribution characteristics of high-power lasers, and effectively compensates the energy attenuation of the Gaussian distribution of the light beam through the hole expansion structure in the central area, so that the difference in penetration of the first and last sections of the weld is reduced from 0.08 mm in the traditional design to 0.02 mm. The additional micro dust collection groove forms a time sequence linkage with the equipment pulse air nozzle, sprays 0.2 MPa compressed air in the laser irradiation gap, and directs the splashes into the dust collection groove. Combined with the automatic slag removal mechanism of the robot, the through hole plugging rate during continuous operation is reduced by 90%. The thickness gradient design of the wedge-shaped observation window can compensate for the field curvature error of the optical system, and the electrode edge distortion rate observed by the operator through the window is less than 0.5%, which significantly improves the visual alignment accuracy. In the actual measurement of the new energy vehicle battery pack production line, the welding process cycle is shortened by 22%, the tool maintenance interval is extended to 8000 welding cycles, and the comprehensive cost is reduced by 18% compared with the scheme of embodiment 1.

Claims

1. A laser welding fixture, characterized by The utility model relates to a kind of laser welding electrode fixing device, including: Base, top surface is equipped with annular positioning slot matched with outer circle of shell assembly; Cover plate, detachably connected with base by magnetic attraction assembly, the cover plate is equipped with welding through-hole; Electrode positioning structure in the middle of cover plate, the positioning structure includes the clamping groove for fixing electrode; Positioning pin is arranged in the circumference of base, and positioning pin fixes cover plate with base.

2. The laser welding fixture of claim 1, wherein: The positioning pin cooperates with the waist type hole provided on the cover plate, the length direction of waist type hole is consistent with the width direction of base, and the cover plate can be moved along the length direction of waist type hole to adjust the position of clamping groove.

3. The laser welding fixture of claim 1, wherein: The cover plate includes positive electrode cover plate, and the electrode positioning structure includes sunken clamping groove provided on the positive electrode cover plate, the depth of sunken clamping groove is 1-2mm, and the bottom of groove is equipped with abutting limit step with the end surface of positive electrode.

4. The laser welding fixture of claim 1, wherein: The cover plate includes negative electrode cover plate, and the electrode positioning structure includes movable clamping groove provided on the negative electrode cover plate, and the movable clamping groove is T-shaped groove suitable for negative electrode;Elastic limit sheet is arranged in the straight section of T-shaped groove.

5. The laser welding fixture of claim 4, wherein: Adjusting allowance area is provided in the T-shaped groove corresponding to movable clamping groove, and the adjusting allowance area is arranged along the radial direction of negative electrode cover plate.

6. The laser welding fixture of claim 1, wherein: The magnetic attraction assembly includes annular magnet embedded in the bottom surface of cover plate and columnar magnet embedded in the top surface of base corresponding to annular magnet, and the inner diameter of annular magnet is gap matched with the outer diameter of columnar magnet.

7. The laser welding fixture of claim 1, wherein: The number of positioning pin is not less than 3, and the pin body is gap matched with the positioning hole of shell assembly along the circumference of annular positioning slot.

8. The laser welding fixture of claim 1, wherein: Threaded hole is arranged on the base and connected with laser welding machine, and the axis of threaded hole is perpendicular to the axis of base.

9. The laser welding fixture of any of claims 1-8, wherein: Single-stage chamfer structure is arranged on the inner wall of welding through-hole, the chamfer angle is 30°-45°, and the chamfer depth is 1 / 3-1 / 2 of hole wall thickness.

10. The laser welding fixture of any one of claims 1-8, wherein: Two diagonal rectangular observation windows are arranged on the surface of cover plate, and positioning scale line is etched on the edge of window.

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