CN112025081A

CN112025081A - Welding method for welding ultrahigh-strength steel of QP980 and above by laser welding machine

Info

Publication number: CN112025081A
Application number: CN202011005382.9A
Authority: CN
Inventors: 王硕; 段磊; 芶毅; 袁婷婷; 王鹏飞; 刘正; 张一鸣; 楚雅杰
Original assignee: SD Steel Rizhao Co Ltd
Current assignee: SD Steel Rizhao Co Ltd
Priority date: 2020-09-23
Filing date: 2020-09-23
Publication date: 2020-12-04
Anticipated expiration: 2040-09-23
Also published as: CN112025081B

Abstract

The invention discloses a method for welding ultrahigh-strength steel of QP980 and above by a laser welding machine, which comprises the following steps: 1) adjusting the working process of the laser welding machine, namely adjusting the inlet section, the outlet section and the middle section; 2) adjusting the position of a protective gas nozzle; 3) adjusting the transverse blowing air pressure; 4) selecting a transition material; 5) cooling by a water cooling device; 6) optimizing welding parameters; 7) monitoring the quality of the welding seam in real time by adopting a QCDS welding seam detection system; 8) optimizing a preheating and annealing device; 9) maintenance of equipment before production welding; the welding method for welding QP980 and above ultrahigh-strength steel by using the laser welding machine is suitable for welding ultrahigh-strength steel with carbon equivalent of more than 0.575%, belongs to poor weldability, belongs to difficult-to-weld materials, and needs higher preheating temperature and strict process; the welding quality of the welding seam is improved by adjusting the position of the protective gas nozzle and the transverse blowing pressure.

Description

Welding method for welding ultrahigh-strength steel of QP980 and above by laser welding machine

Technical Field

The invention relates to the technical field of steel making, in particular to a method for welding ultrahigh-strength steel with QP980 or above by using a laser welding machine.

Background

The welding method for welding high-strength steel by using a laser welding machine adopts the steps of clamping strip steel to be welded, conventional shearing, lapping table micro-motion to determine the shearing amount of secondary shearing, lapping table strip steel butt joint, high-power annealing, leveling, compressed air cooling, preheating, pre-leveling, laser conduction welding, secondary high-power annealing, leveling, welding completion and the like. The quality of the shearing surface of the strip steel is improved through secondary shearing; the yield strength can be reduced through high-power air-through annealing, the strip shape of a welding area is effectively improved, and material grains can be improved; the material quality of the strip steel in the welding area can be improved through air cooling, so that the occurrence of fracture of a welding line thermal induction area is effectively avoided.

The prior art scheme has the following defects: 1. the secondary annealing requires the welding machine trolley to travel for the second time, so that the welding efficiency is reduced, the continuity of a machine set is influenced, and the production line is easy to stop; 2. the secondary shearing has different effects on the strip steel with different thicknesses, and whether the secondary shearing is used or not is determined according to the strip steel with different thicknesses; 3. the cooling effect by adopting the compressed air is not obvious, and the temperature reduction effect is poor; 4. optimization and adjustment of welding parameters is not involved. Therefore, a method for welding QP980 or above ultrahigh-strength steel by using a laser welding machine is urgently needed to solve the problem that a production line is stopped due to discontinuity of a machine set.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a method for welding QP980 and above ultrahigh-strength steel by using a laser welding machine.

The technical scheme adopted by the invention for solving the technical problems is as follows: a welding method for welding QP980 and above ultrahigh strength steel by a laser welding machine comprises the following steps:

1) adjusting the working process of the laser welding machine, namely adjusting the inlet section, the outlet section and the middle section;

2) adjusting the position of a protective gas nozzle, setting the pressure of the protective gas to be 28L/min, adjusting the angle and the position of the nozzle, wherein the center line of the upper nozzle is deviated to the driving side by 1mm, and the center line of the lower nozzle is deviated to the operating side by 1 mm;

3) adjusting transverse blowing air pressure, finishing the pressure through a test paper sheet experiment, placing an A4 paper sheet with the size of 50 x 50mm at a transverse suction outlet, and adjusting the pressure until the paper sheet is sucked and does not fall off;

4) selecting a transition material, namely adopting 780DP steel with yield strength lower than QP980 as the transition material if the material is sufficient, and adopting 2-grade 780DP steel with yield strength lower than QP980 as the transition material if the material is insufficient;

5) the steel strip is cooled by a water cooling device and high-pressure water, a set of high-pressure water nozzle is added on the outer side of a crescent shear part of the welding machine, the high-pressure water nozzle mainly comprises a flat nozzle which is obliquely arranged at an angle of 45 degrees downwards close to the outer side, a nozzle fixing support, a water pipeline, a flow control valve and a pressure gauge, and the pressure of the nozzle flow control valve is controlled to rapidly cool the steel strip after the steel strip is rapidly heated;

6) optimizing welding parameters, and adjusting welding speed V, laser power P, focal position, butt joint gap d, preheating power P1 and annealing power P2;

7) monitoring the quality of the welding seam in real time by adopting a QCDS welding seam detection system;

8) the preheating and annealing device is optimized, and the condition that the power at two sides of the welding line is insufficient is reduced by modifying the opening and closing time of the preheating device and the annealing device;

9) equipment maintenance before production welding, focus lens maintenance, fine adjustment of the laser position of a condenser lens, laser welding gap offset debugging and adjustment of the focus position of the condenser lens.

Specifically, the step of adjusting the inlet section in step 1 is: 1) the lower part of the inlet clamping roller → the No. 1 grating does not detect the strip steel → the middle position of the lifting roller → the No. 1 grating detects the strip steel, the No. 2 grating does not detect → the inlet pinch roller faces downwards and starts working; 2) the 2# grating detects the strip steel → the inlet loop rises → the lifting roller 1# goes downwards → the positioning is finished; 3) centering of the lift roller 1# and the lift roller 2# starts work → centering automatic program starts → inlet clamping table clamping → cross clamp roller loosening → centering of the lift roller 1# and the lift roller 2# returns → end of the inlet section.

Specifically, the step of adjusting the outlet section in step 1 is: 1) opening a C-shaped frame of a welding machine to an operation position → leading an outlet pinch roll to move downwards → no strip tail is detected by a # 1 grating → leading the outlet pinch roll to start → leading an outlet loop to move upwards → leading a lifting roll 1# and a lifting roll 2# to move downwards to a middle lifting roll 3# to move downwards; 2) the strip tail cannot be detected by the No. 2 grating → the positioning of the strip steel tail is finished → the lifting roller No. 2 and the lifting roller No. 3 descend → the clamping of the outlet clamping table → the clamping of the outlet cross; 3) short stroke position of the outlet clamping table → descending of the outlet loop, lifting of the pinch roller → start of centering of the lifting roller 3# and the lifting roller 4# → clamping of the outlet clamping table → loosening of the outlet cross clamping → centering and recovery of the lifting roller 3# and the lifting roller 4 #.

Specifically, the step of adjusting the intermediate stage in step 1 includes: lower cutting edge up → punch down → upper cutting edge down → rolling wheel down → punch up → lower cutting edge down → upper cutting edge up → laser ready → laser on → laser shutter off → laser head down → clamping table to welding position → shear scrap drive on → welding process start → clamping table loosen after welding completion → all lifting rollers to lifting position → clamping table to cutting position.

Specifically, the transition mode that 780DP steel with yield strength lower than that of QP980 is sufficiently adopted as the transition material in the step 4 is 780DP, QP980, 780DP and QP 980; the transition mode of insufficient material adopting 2-grade 780DP steel with yield strength lower than that of QP980 as the transition material is 780DP, QP980 · 780 DP.

Specifically, in the step 6, the welding speed V is 14m/min, the laser power P is 12Kw, the focal position is-1.3 mm to-4 mm when the thickness is 2-6mm, the butt joint gap d is 0-1mm, the preheating power P130% -50% and the annealing power P230% -50%.

Specifically, the step of fine-tuning the laser position of the condenser lens in step 9 is: 1) moving a clamping table to a welding position, enabling a welding wheel to move downwards, moving the welding wheel to a strip steel position at a slow speed, and performing dotting test by using a hand-held laser button, wherein the laser time is 40ms, and laser spots can be left when the laser is beaten on a steel plate; 2) and a dial indicator is arranged at the mechanical arm of the focusing mirror, the position of the focusing mirror is adjusted by rotating a knob at the mechanical arm, and the rotation is 0.25 mm until the laser point is adjusted to the middle position of the two steel plates.

Specifically, the debugging method of laser welding gap offset debugging in step 9 includes: 1) adjusting the laser mode to a dotting mode; 2) normally welding in a dotting mode; 3) and checking whether the welding seams of the driving side and the operating side of the strip steel deviate or not by using a magnifying glass.

Specifically, the step of adjusting the focal position of the condenser lens in step 9 is: 1) after the condenser lens is installed, the paper is installed between the upper supporting wheel and the lower supporting wheel; 2) the offset of the focal position is set from 0, +1, +2, +3, +4, +5, -1, -2, -3, -4, -5 in the welding parameter page in sequence, one parameter is set for one time for laser shooting, all points are compared after all points are shot, and the point with the smallest circle is set as 0 point.

The invention has the following beneficial effects:

the welding method for welding QP980 and above ultrahigh-strength steel by using the laser welding machine is suitable for welding ultrahigh-strength steel with carbon equivalent of more than 0.575%, belongs to poor weldability, belongs to difficult-to-weld materials, and needs higher preheating temperature and strict process; the welding quality of the welding seam is improved by adjusting the position of the protective gas nozzle and the transverse blowing pressure; the state of the laser welding machine is fully guaranteed through necessary equipment maintenance before production; the preheating and annealing device is optimized, so that the strip breakage caused by low preheating and annealing power on the welding line operation side and the welding line driving side is avoided; summarizing high-strength steel with different thicknesses by optimizing welding parameters and using an empirical formula; the water cooling device is adopted for cooling, so that the quality of the welding seam is improved; the transition mode of transition materials is adopted.

Drawings

Fig. 1 is a first structural diagram of an adjusting inlet section.

Fig. 2 is a schematic structural diagram two of the adjustment inlet section.

Fig. 3 is a schematic diagram of a structure of the adjustment inlet section.

Fig. 4 is a first schematic structural diagram of the adjusting outlet section.

Fig. 5 is a schematic structural diagram two of the adjusting outlet section.

Fig. 6 is a schematic diagram of a structure of an adjusting outlet section three.

FIG. 7 is a first schematic view of the structure of the middle section of the adjustment.

FIG. 8 is a second schematic structural view of the middle section of the adjustment.

Fig. 9 is a third schematic structural view of the middle section of the adjustment.

FIG. 10 is a fourth schematic view of the structure of the middle section of the adjustment device.

Fig. 11 is a schematic view of a structure for adjusting the position of the shielding gas nozzle.

In the figure: 1-an upper nozzle; 2-a lower nozzle; 3-operation side; 4-drive side.

Detailed Description

The technical scheme in the embodiment of the invention is clearly and completely further explained in detail in the following with the accompanying drawings. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A background introduction of a method for welding QP980 and above ultra-high strength steel by a laser welding machine comprises the following steps:

1. mechanical properties of material

2. Chemical composition of material

3. Material welding performance

The carbon content is the main factor in carbon steel that determines strength and weldability. Alloy steels (mainly low alloy steels) have various alloying elements besides carbon that play an important role in the strength and weldability of steel. To facilitate the expression of the strength properties and the welding properties of these materials, they are simply expressed in terms of carbon equivalent by statistics of a large number of test data. There are many indicators of carbon equivalent, such as tensile strength carbon equivalent, yield strength carbon equivalent, weld carbon equivalent, and also crack susceptibility (also carbon equivalent in nature). The carbon equivalent of each element is expressed as 1/X, X being generally a positive integer, determined by statistical data. The sum of the carbon equivalent calculations for several elements, i.e. the sum of the individual 1/X values.

C equivalent [ C + Mn/6+ (Cr + Mo + V)/5+ (Ni + Cu)/15 ]. multidot.100%

In the formula: C. mn, Cr, Mo, V, Ni, Cu are the contents of the elements in the steel

The carbon equivalent Ceq (percent) value can be calculated as follows:

Ceq＝C+Mn/6+(Cr+V+Mo)/5+(Cu+Ni)/15

(allowable deviation of carbon equivalent Ceq + 0.03%) formula for carbon equivalent CE of International society for welding (IIW)

CE＝[W(c)+W(Mn)/6+[W(Cr)+W(Mo)+W(V)]/5+[W(Ni)+W(Cu)]/15

The calculated QP980 carbon equivalent is more than 0.575 percent, which belongs to poor weldability and difficult-to-weld materials, and a higher preheating temperature and a strict technological method are required.

A welding method for welding QP980 and above ultrahigh strength steel by a laser welding machine comprises the following steps:

1. work flow of welding machine

1.1 inlet section

(1) The lower part of the inlet clamping roller → no strip steel is detected by the No. 1 grating → the middle position of the lifting roller → the No. 1 grating detects no strip steel by the No. 2 grating → the inlet pinch roller faces downwards and starts working, as shown in figure 1;

(2) the 2# grating detects the strip steel → the inlet loop rises → the lifting roller 1# goes downwards → the positioning is finished, as shown in fig. 2;

(3) centering of the lift roller 1# and the lift roller 2# starts work → centering automatic program starts → entrance pinch table pinching → cross pinch roller loosening → centering of the lift roller 1# and the lift roller 2# returns → entrance end, as shown in fig. 3.

1.2 Outlet section

(1) The C-shaped frame of the welding machine is opened to an operation position → the outlet pinch roll is downward → No strip tail (from the existence to the nonexistence) can not be detected by the No. 1 raster → the beginning of the outlet pinch roll → the outlet loop is raised → the lifting roll 1# and the lifting roll 2# are lowered to the middle lifting roll 3# to the low position, as shown in FIG. 4;

(2) no strip tail is detected by the No. 2 grating → the positioning of the strip steel tail is finished → the lifting roller No. 2 and the lifting roller No. 3 descend → the clamping of the outlet clamping table → the clamping of the outlet cross, as shown in FIG. 5;

(3) short stroke position of the outlet clamping table → descending of the outlet loop, lifting of the pinch roller → start of centering of the lifting roller 3# and the lifting roller 4# → clamping of the outlet clamping table → loosening of the outlet cross clamping → centering and returning of the lifting roller 3# and the lifting roller 4#, as shown in fig. 6.

1.3 middle section

As shown in fig. 7-10, the lower cutting edge is up → the punch is down (if selected) → the upper cutting edge is down → the laminating wheel is down → the punch is up → the lower cutting edge is down → the upper cutting edge is up → the laser is ready → the laser is on → the laser shutter is off → the laser head is down → the clamping table is to the welding position → the scrap material drive is on → the welding process begins → the clamping table is unclamped after the welding is completed → all the lifting rollers are unclamped to the lifting position → the clamping table is to the cutting position.

2. Adjustment of the position of the shielding gas nozzle

(1) The pressure of the protective gas is 28L/min;

(2) the shield gas nozzle position, the nozzle angle and position were adjusted with the centerline of the upper nozzle 1 offset to the drive side by 41mm and the centerline of the lower nozzle 2 offset to the operating side by 31mm as shown in fig. 11.

3. Adjusting the horizontal blowing pressure

The horizontal blowing gas pressure is properly adjusted, the horizontal suction pressure is small, welding slag is easy to splash, welding beading can occur on the surface of a welding seam, the pressure is tested through a test paper sheet without a pressure detection device, a A4 paper sheet with the size of 50 x 50mm is placed at the horizontal suction outlet, and after the paper sheet is sucked, the pressure is adjusted until the paper sheet is sucked and does not fall.

4. Transition material selection

(1) The first scheme is as follows: under the condition of sufficient materials, 780DP steel with yield strength lower than QP980 is adopted as a transition material, and the transition mode is as follows:

production sequence number	Material
			1	780DP
2	QP980
		3	780DP
4	QP980
		...	...

(2) Scheme II: under the condition of insufficient materials, 2-grade 780DP steel with yield strength lower than QP980 is adopted as a transition material, and the transition mode is as follows:

5. cooling by water cooling device

The heat treatment device is characterized in that high-pressure water is adopted for cooling, a set of high-pressure water nozzles are additionally arranged on the outer side of a crescent shear component of the welding machine, so that the heat treatment process is realized, and the component mainly comprises a flat nozzle, a nozzle fixing support, a water pipeline, a flow control valve and a pressure gauge, wherein the flat nozzle is obliquely arranged by 45 degrees downwards from the outer side. The pressure of the nozzle flow valve is controlled, so that the strip steel is rapidly heated and then rapidly cooled, and the quality of the strip steel in a welding area is improved.

6. Optimizing welding parameters

7. Real-time monitoring of weld quality using QCDS weld detection system

The QCDS parameter curve can be used for judging the quality of the welding seam and the reason of the welding seam defect, for example, the plate shape defect of the raw material is mainly represented by transverse edge waves, middle waves and longitudinal waves. Although the clamping table clamps the plate to eliminate these defects primarily, in actual production, it is still found that many weld tears are closely related to poor plate shape. When the defects exist, the running amount of raw material tissues at the boundary of the defects is slightly different from other parts when the positioning wheel and the welding wheel are rolled over, so that the outlet section and the inlet section after the double-cutting shear are cut are not parallel to present an uneven section, the joint of the two sections is not zero, the molten pool at the larger part of the joint has liquid leakage, and finally the upper surface of the welding line at the larger part of the joint is not full. Once the degree of the unsaturation of a certain position is large or the unsaturation is positioned at the edge of the strip steel and is not sheared off, the welding seam is likely to be torn off at the position, and the strip is broken. In addition, the plate shape defect can also cause the staggered layer before the welding of the head and the tail of the strip, and finally the welding seam with poor quality appears.

8. Optimized preheating and annealing device

The most important parameters for welding the high-strength steel are preheating power and annealing power, and because certain time is needed for heating and cooling the preheating heater and the annealing heater in the welding process, the power of a welding seam start welding area and a final welding area is insufficient, and the welding effect is poor.

The situation of insufficient power at two sides of the welding seam is reduced by modifying the opening and closing time of the preheating device and the annealing device.

9. Necessary maintenance of equipment before production

9.1 maintenance of the focusing lens, Fine adjustment of the laser position of the condensing lens

(1) Moving a clamping table to a welding position, enabling a welding wheel to move downwards, moving the welding wheel to a strip steel position at a slow speed, and using a hand-held laser button to perform dotting test (the laser time is 40ms) to enable a laser spot to be left on a steel plate after being hit;

(2) the laser point is deviated to the inlet side, a dial indicator is installed at the mechanical arm of the focusing mirror, the position of the focusing mirror is adjusted by rotating a knob at the mechanical arm, and the rotation is 0.25 mm until the laser point is adjusted to be in the middle position of the two steel plates.

9.2 laser welding gap offset debugging (dotting mode)

The purpose is as follows: and detecting whether the welding gap deviates or not and detecting whether the laser emitted by the focusing lens deviates or not.

The debugging method comprises the following steps:

(1) adjusting the laser mode to a dotting mode;

(2) normally welding in a dotting mode;

(3) and checking whether the welding seams of the driving side and the operating side of the strip steel deviate or not by using a magnifying glass.

And (3) detection results:

(1) if there is only one or opposite direction of the offset on the drive side 4 and the operating side 3;

(2) the need for adjusting the weld gap is justified by adjusting the amount of compensation for the lateral movement of the clamping table;

(3) if the two sides of the driving side 4 and the operating side 3 both deviate from the same direction, the need of adjusting the collecting mirror is proved, and the moment arm of the collecting mirror is adjusted by detecting through a dial indicator and rotating a knob.

9.3 adjusting the focal position of the condenser

(1) After the condenser lens is installed, the paper is installed between the upper supporting wheel and the lower supporting wheel;

(2) setting the offset of the focal position on a welding parameter page to be 0, +1, +2, +3, +4, +5, -1, -2, -3, -4, -5, and setting one parameter for laser striking once every time;

(3) after all the points are printed, all the points are compared, and the point of the minimum circle is set as 0 point;

(4) the setting method comprises the following steps: firstly, the focal length of the laser is adjusted to the offset of the optimal focal length on a parameter page, then an adjustment mode is opened on a laser focal point setting page, and then the offset is clicked.

The present invention is not limited to the above embodiments, and any structural changes made under the teaching of the present invention shall fall within the scope of the present invention, which is similar or similar to the technical solutions of the present invention.

The techniques, shapes, and configurations not described in detail in the present invention are all known techniques.

Claims

1. A welding method for welding QP980 and above ultrahigh strength steel by a laser welding machine is characterized by comprising the following steps:

2. The method for welding the ultra-high strength steel QP980 or above by the laser welder according to claim 1, wherein the step of adjusting the inlet section in the step 1 comprises the following steps: 1) the lower part of the inlet clamping roller → the No. 1 grating does not detect the strip steel → the middle position of the lifting roller → the No. 1 grating detects the strip steel, the No. 2 grating does not detect → the inlet pinch roller faces downwards and starts working; 2) the 2# grating detects the strip steel → the inlet loop rises → the lifting roller 1# goes downwards → the positioning is finished; 3) centering of the lift roller 1# and the lift roller 2# starts work → centering automatic program starts → inlet clamping table clamping → cross clamp roller loosening → centering of the lift roller 1# and the lift roller 2# returns → end of the inlet section.

3. The method for welding QP980 and above ultra-high strength steels by using the laser welder as claimed in claim 1, wherein the step of adjusting the outlet section in the step 1 comprises the following steps: 1) opening a C-shaped frame of a welding machine to an operation position → leading an outlet pinch roll to move downwards → no strip tail is detected by a # 1 grating → leading the outlet pinch roll to start → leading an outlet loop to move upwards → leading a lifting roll 1# and a lifting roll 2# to move downwards to a middle lifting roll 3# to move downwards; 2) the strip tail cannot be detected by the No. 2 grating → the positioning of the strip steel tail is finished → the lifting roller No. 2 and the lifting roller No. 3 descend → the clamping of the outlet clamping table → the clamping of the outlet cross; 3) short stroke position of the outlet clamping table → descending of the outlet loop, lifting of the pinch roller → start of centering of the lifting roller 3# and the lifting roller 4# → clamping of the outlet clamping table → loosening of the outlet cross clamping → centering and recovery of the lifting roller 3# and the lifting roller 4 #.

4. The method for welding ultra-high strength steel QP980 or above by using the laser welder as claimed in claim 1, wherein the step of adjusting the middle section in the step 1 comprises the following steps: lower cutting edge up → punch down → upper cutting edge down → rolling wheel down → punch up → lower cutting edge down → upper cutting edge up → laser ready → laser on → laser shutter off → laser head down → clamping table to welding position → shear scrap drive on → welding process start → clamping table loosen after welding completion → all lifting rollers to lifting position → clamping table to cutting position.

5. The method for welding QP980 and above ultra-high strength steels by using a laser welder as claimed in claim 1, wherein the transition mode of the material in step 4 is 780DP, QP980, 780DP and QP 980-; the transition mode of insufficient material adopting 2-grade 780DP steel with yield strength lower than that of QP980 as the transition material is 780DP, QP980 · 780 DP.

6. The method for welding the ultrahigh-strength steel of the QP980 or above by the laser welding machine as claimed in claim 1, wherein the welding speed V in the step 6 is 14m/min, the laser power P is 12Kw, the focal position is-1.3 mm to-4 mm when the thickness is in the range of 2-6mm, the butt joint gap d is 0-1mm, the preheating power P130% -50% and the annealing power P230% -50%.

7. The method for welding ultra-high strength steel QP980 and above by using a laser welder as claimed in claim 1, wherein the step of fine-tuning the laser position of the condenser lens in the step 9 is as follows: 1) moving a clamping table to a welding position, enabling a welding wheel to move downwards, moving the welding wheel to a strip steel position at a slow speed, and performing dotting test by using a hand-held laser button, wherein the laser time is 40ms, and laser spots can be left when the laser is beaten on a steel plate; 2) and a dial indicator is arranged at the mechanical arm of the focusing mirror, the position of the focusing mirror is adjusted by rotating a knob at the mechanical arm, and the rotation is 0.25 mm until the laser point is adjusted to the middle position of the two steel plates.

8. The method for welding QP980 and above ultra-high strength steels by using a laser welder as claimed in claim 1, wherein the debugging method for debugging the laser welding gap offset in step 9 comprises the following steps: 1) adjusting the laser mode to a dotting mode; 2) normally welding in a dotting mode; 3) and checking whether the welding seams of the driving side and the operating side of the strip steel deviate or not by using a magnifying glass.

9. The method for welding ultra-high strength steel QP980 and above by using the laser welding machine as claimed in claim 1, wherein the step of adjusting the focal position of the condenser lens in the step 9 is as follows: 1) after the condenser lens is installed, the paper is installed between the upper supporting wheel and the lower supporting wheel; 2) the offset of the focal position is set from 0, +1, +2, +3, +4, +5, -1, -2, -3, -4, -5 in the welding parameter page in sequence, one parameter is set for one time for laser shooting, all points are compared after all points are shot, and the point with the smallest circle is set as 0 point.