阅读说明：本技术 用于减少不锈钢非焊透型焊接气孔生成率的焊接方法 (Welding method for reducing generation rate of non-welding-through type welding pores of stainless steel ) 是由 李午红 张国瑜 邢飞 王传强 于 2020-12-22 设计创作，主要内容包括：本发明公开了一种用于减少不锈钢非焊透型焊接气孔生成率的焊接方法,该方法采用离焦量为20～30mm的摆动激光,结合TIG热源对不锈钢进行非焊透型焊接；TIG焊枪通过可调节位移式工装固定到摆动激光加工头后侧,调整钨针到不锈钢试板的距离,钨针与摆动激光光束之间的夹角,设置参数,并开始进行焊接。本发明的方法可用于不锈钢非焊透焊接,具有高效率、高性能和高适应性,解决了焊缝根部出现的微小气孔、裂纹等焊接缺陷,达到了焊接标准,满足了使用要求。(The invention discloses a welding method for reducing the generation rate of non-welding through type welding pores of stainless steel, which adopts swing laser with defocusing amount of 20-30 mm and combines a TIG heat source to perform non-welding through type welding on the stainless steel; and the TIG welding gun is fixed to the rear side of the swinging laser processing head through an adjustable displacement type tool, the distance from the tungsten needle to the stainless steel test plate, the included angle between the tungsten needle and the swinging laser beam, the setting parameters and the start of welding are adjusted. The method can be used for stainless steel non-penetration welding, has high efficiency, high performance and high adaptability, solves the welding defects of tiny air holes, cracks and the like at the root of the welding line, achieves the welding standard and meets the use requirement.)

1. A welding method for reducing the generation rate of non-welding-through type welding pores of stainless steel is characterized by comprising the following steps of: the method adopts a swing laser with defocusing amount of 20-30 mm, and combines a TIG heat source to perform non-welding transparent welding on the stainless steel;

the specific process is as follows: selecting proper stainless steel, performing swing laser cleaning on a welding surface of the stainless steel, and assembling and pressing; selecting a tungsten needle with a proper diameter, and grinding the contact end of the tungsten needle and the test plate to a proper sharpness; finding the relative position of the swinging laser spot and the butt weld through an actuating mechanism, and measuring the defocusing amount at each point in the welding path; and the TIG welding gun is fixed to the rear side of the swinging laser processing head through an adjustable displacement type tool, the distance from the tungsten needle to the stainless steel test plate, the included angle between the tungsten needle and the swinging laser beam, the setting parameters and the welding are started.

2. The welding method for reducing the generation rate of non-weld-through type weld blowholes in stainless steel according to claim 1, characterized in that: the diameter of a focusing spot of the swinging laser is more than or equal to 0.5 mm.

3. The welding method for reducing the generation rate of the non-weld-through type weld blowholes of stainless steel according to claim 1 or 2, characterized in that: the output power of the swing laser is more than or equal to 2kw, the current of the welding machine is 130A-140A, the welding speed is less than or equal to 0.5m/min, the swing amplitude is 0.2-0.5 mm, and the swing frequency is 100-200 HZ.

4. A weaving laser TIG hybrid welding method for reducing non-welding vent generation rate of stainless steel according to claim 1, characterized in that: the collimation and focusing ratio of the swinging laser welding processing head is 2.8-3.0.

5. The welding method for reducing the generation rate of non-weld-through type weld blowholes in stainless steel according to claim 1, characterized in that: the tungsten needle diameter of the TIG heat source is 2-3 mm, the dry elongation is 8-10 mm, the distance between the tungsten needle and the surface of the workpiece is 3-4 mm, the sharpness of the contact end of the tungsten needle and the workpiece is 30 +/-2 degrees, and the extension line of the tungsten needle is intersected with the center of the swinging laser spot.

6. The welding method for reducing the generation rate of the non-weld-through type weld blowholes of stainless steel according to claim 1 or 5, characterized in that: the included angle between the tungsten needle and the swinging laser beam is 20-30 degrees.

7. The welding method for reducing the generation rate of non-weld-through type weld blowholes in stainless steel according to claim 1, characterized in that: and in the welding process, the molten pool is protected by argon, and the flow rate of the argon is 15-20L/min.

8. The welding method for reducing the generation rate of non-weld-through type weld blowholes in stainless steel according to claim 1, characterized in that: the fusion depth range of the welding by the method is 2.5-3.6 mm.

9. The welding method for reducing the generation rate of non-weld-through type weld blowholes in stainless steel according to claim 1, characterized in that: and in the welding process, the air pressure is 0.2-0.4 MPa.

10. The welding method for reducing the generation rate of non-weld-through type weld blowholes in stainless steel according to claim 1, characterized in that: after the parameters are set, the head and the tail of the test board are tack welded by holding the swing laser welding machine before welding.

Technical Field

The invention relates to the technical field of laser welding, in particular to a welding method for reducing the generation rate of stainless steel non-welding through type welding pores.

Background

Non-consumable electrode inert gas welding (TIG welding for short) is an arc welding method using tungsten electrode as electrode material and inert gas argon as protective gas, and is characterized by that it utilizes special TIG welding gun to spray argon gas flow from nozzle, and the protective arc is isolated from air, and the electric arc and molten pool are combusted in the surrounding of gas flow layer, and melted, and two separated metals are firmly connected together by means of wire-filling or wire-non-filling so as to form permanent joint. However, TIG welding has limitation on the penetration depth, and cannot meet the requirement of the penetration depth of more than 3 mm.

Laser welding is an efficient precision welding method using a laser beam with high energy density as a heat source. The laser radiation heats the surface of the workpiece, the surface heat is diffused inwards through heat conduction, and parameters such as the width, energy, peak power, repetition frequency and the like of laser pulses are controlled to melt the workpiece, form a specific molten pool and form a permanent joint. However, laser welding is very demanding in terms of gap requirements due to high energy density, and can produce process pinholes during deep fusion welding. This is because the melting-solidification process of the base metal is completed in a very short time during the welding process, so that some gas in the molten pool cannot escape, and thus the gas is retained in the weld joint along with the solidification of the molten pool, and the mechanical properties of the weld joint cannot meet the use requirements.

The laser TIG hybrid welding technology is a welding method which combines two heat sources with completely different physical property energy transmission mechanisms and acts on the same processing position, the combination of laser and TIG electric arc enables the two heat sources to give full play to respective advantages and mutually makes up for the defects of the other heat source, thereby forming a high-efficiency and stable heat source. In this manner, TIG arc energy dominates the welding process and laser assisted TIG arcs are generally used that are insufficient to form the deep-melted keyhole. The single TIG welding is easily affected by environmental factors, particularly, welding defects such as undercut, hump and the like easily occur when the welding speed is high, and when the laser TIG composite welding is performed, the arc is stably burnt and attracted by the light-induced plasma, so that the phenomenon of arc drifting or breaking is not easily generated even when the high-speed welding is performed.

In the case of non-penetration of stainless steel, due to the fact that the root of a molten pool is instantly solidified due to the fact that a large temperature difference occurs between the bottom of a non-penetration base metal and the molten pool, and welding defects such as micro air holes and cracks occur at the root of a welding line, the three process methods of TIG welding, laser welding and laser TIG composite welding cannot be effectively controlled, and at present, no suitable process is available for achieving non-penetration welding of stainless steel.

Disclosure of Invention

The invention aims to provide a welding method for reducing the generation rate of stainless steel non-penetration type welding pores aiming at the defects of the prior art, the method can be used for stainless steel non-penetration welding, has high efficiency, high performance and high adaptability, solves the welding defects of tiny pores, cracks and the like at the root of a welding seam, achieves the welding standard and meets the use requirement.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a welding method for reducing the generation rate of non-welding-through type welding air holes of stainless steel is characterized in that swing laser with defocusing amount of 20-30 mm is adopted, and a TIG heat source is combined to perform non-welding-through type welding on the stainless steel;

the specific process is as follows: selecting proper stainless steel, performing swing laser cleaning on a welding surface of the stainless steel, and performing group-to-group press mounting on a special welding tool to eliminate the influence of gaps and misalignment; selecting a tungsten needle with a proper diameter, and grinding the contact end of the tungsten needle and the test plate to a proper sharpness; finding the relative position of the swinging laser spot and the butt-joint welding seam through an actuating mechanism, and measuring the defocusing amount at each point in the welding path to ensure the consistency of the defocusing amount at each position of the path scanned by the light beam; and the TIG welding gun is fixed to the rear side of the swinging laser processing head through an adjustable displacement type tool, the distance from the tungsten needle to the stainless steel test plate, the included angle between the tungsten needle and the swinging laser beam, the setting parameters and the welding are started.

Furthermore, the diameter of a focusing spot of the swinging laser is more than or equal to 0.5 mm.

Furthermore, the output power of the swing laser is more than or equal to 2kw, the current of the welding machine is 130A-140A, the welding speed is less than or equal to 0.5m/min, the swing amplitude is 0.2-0.5 mm, and the swing frequency is 100-200 HZ.

Further, the collimation and focusing ratio of the swinging laser welding processing head is 2.8-3.0.

Furthermore, the diameter of a tungsten needle of the TIG heat source is 2-3 mm, the dry elongation is 8-10 mm, the distance between the tungsten needle and the surface of the workpiece is 3-4 mm, the sharpness of the contact end of the tungsten needle and the workpiece is 30 +/-2 degrees, and the extension line of the tungsten needle is intersected with the center of the swinging laser spot.

Furthermore, the included angle between the tungsten needle and the swinging laser beam is 20-30 degrees.

Further, argon is adopted to protect a molten pool in the welding process, and the flow rate is 15-20L/min.

Furthermore, the fusion depth range of the welding performed by the method is 2.5-3.6 mm.

Furthermore, in the welding process, the air pressure is 0.2-0.4 MPa.

Further, after the parameters are set, before welding, in order to prevent the influence of deformation on the gap in the welding process, the handheld swing laser welding is used for fixing the head and the tail of the test plate in a point mode, and then welding is started.

Compared with the prior art, the invention has the beneficial effects that:

1. by controlling the defocusing amount of the swinging laser beam, the foci and the light spots after being defocused disperse the concentration of energy density, the penetrating power of the swinging laser beam is weakened, the stability of small-hole deep fusion welding is improved, and the porosity and the size of a single air hole are greatly reduced; after the welding head is compounded with a TIG heat source, the surface width of a molten pool is increased, the solidification time of the molten pool is delayed, and then under the action of the swinging and swinging laser, the probability of air hole escape is given in time and space, so that a good joint with low air hole rate or even no air hole in the interior of a welding seam is obtained.

2. According to the invention, by controlling key process parameters such as the power, the swing amplitude, the swing frequency, the defocusing amount at the focused spot of the swing laser, the welding speed, the flow of protective gas, the extension length of the tungsten needle, the horizontal distance between the tungsten needle and the swing laser spot and the like, the strength requirement of a welding seam is met and the surface of the welding seam is smooth and has zero splashing through the synergistic effect of the process parameters, and the process problems that the internal gas hole crack rate of an unwelded joint is high and the mechanical property of the joint is lower than that of a base metal are solved.

3. The invention solves the problems of strict gap requirement of single-swing laser welding groups, insufficient TIG welding fusion depth and large heat input by compounding the swing laser light source and the TIG heat source.

Drawings

Fig. 1 is a view of a connection of an oscillating laser welding head and a TIG welding gun of the present invention.

FIG. 2 is a photograph of an ordinary weld RT test.

FIG. 3 is a photograph of an RT test of a weld joint in the welding method of the present invention obtained in the examples.

FIG. 4 is a schematic view of a Y-groove.

In fig. 1: 1. the TIG welding gun and the swinging laser processing head are connected with a tool; 2. TIG welding gun, 3, swing laser processing head.

Detailed Description

In order to better understand the technical content of the present invention, specific embodiments are described below with reference to the accompanying drawings.

In this disclosure, aspects of the present invention are described with reference to the accompanying drawings, in which a number of illustrative embodiments are shown. Embodiments of the present disclosure are not necessarily intended to include all aspects of the invention. It should be appreciated that the various concepts and embodiments described above, as well as those described in greater detail below, may be implemented in any of numerous ways.

To further illustrate the technical effects of the technical solution of the present invention, the following examples are provided.

In the embodiment, an IPG10KW optical fiber swinging laser is used as a swinging laser source, the maximum output power is 10KW, and the swinging laser wavelength is 1064 nm; the collimation and focusing ratio of the swinging laser welding processing head is 2.8, and the diameter of the optical fiber core is 200 mu m; the execution mechanism adopts a KUKA 60 robot; the welder is selected from FRONIUS MW 3000; the joint is in the form of a Y-groove, as shown in fig. 4, and in another embodiment the joint is in the form of a T-joint, a cross-joint or a keyed butt joint.

A304 stainless steel test plate with a specification of 300mm × 150mm × 6mm was selected, and the test piece was fixed in a butt joint manner using a welding jig. The relative position of the facula and the butt-joint seam is accurately found through the teaching of the robot, and the relative positions of the facula, the tungsten needle and the butt-joint seam are guaranteed to have no deviation. In the welding process, the swing laser power is 2KW, the swing amplitude is 0.2mm, the swing frequency is 100HZ, the defocusing amount is 20mm, the welding speed is 0.3m/min, and the welding machine current is 140A. The diameter of a tungsten needle is 2.4mm, the dry elongation of the tungsten needle is 8mm, the distance between the tungsten needle and a workpiece is 4mm, and the sharpness of the contact end of the tungsten needle and the workpiece is 30 degrees; as shown in fig. 1, a TIG welding gun 2 is fixed to the rear side of a swing laser processing head 3 through a TIG welding gun and swing laser processing head connecting tool 1, the TIG welding gun and swing laser processing head connecting tool 1 is an adjustable displacement type tool, and an included angle between a tungsten needle and a swing laser beam is 30 °. And in the welding implementation process, the molten pool is protected by argon, the flow rate is 20L/min, the optical element in the welding processing head is protected by compressed air, and the air pressure is 0.2-0.4 MPa.

The obtained welding line is a common butt welding line, the width of the welding line is about 5mm, and the fusion depth is 3.6 mm. An RT detection photo of a common welding seam is shown in figure 2, and as can be seen from the figure, a plurality of air holes (circled parts in the figure) appear in a detection sheet and have obvious defects; the picture of the welding method RT detection is shown in the attached figure 3, and the picture shows that the welding line in the detection piece is attractive in shape and has no obvious defects.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the protection scope of the present invention should be determined by the appended claims.