阅读说明：本技术 一种自润滑随焊摩擦拘束微搅拌摩擦焊方法 (Self-lubricating welding-following friction constraint micro-friction stir welding method ) 是由 封小松 夏佩云 董吉义 赵慧慧 于 2019-11-20 设计创作，主要内容包括：本发明的一种自润滑随焊摩擦拘束微搅拌摩擦焊方法,在薄壁构件搅拌摩擦焊搅拌头外部附加一个随搅拌头一起旋转的低摩擦系数辅助轴肩,该轴肩采用具有一定耐高温能力的自润滑材料,其对被焊材料进行局部拘束和焊后压延,保持焊前及焊后工件平整。同时可对该辅助轴肩对工件实施压力或位移调整与控制,辅助轴肩与搅拌头一起旋转,采用近无倾角的焊接方式,可克服静止轴肩前进阻力过大的问题,同时因为与母材具有非常小的摩擦系数,其产热量较低,不会显著增加焊接过程的热输入,可以确保实现对薄壁工件的动态拘束效果同时不影响焊接过程。本发明可有效解决薄壁构件搅拌摩擦焊过程存在装配困难、易变形失稳、焊后变形较大等问题。(The invention relates to a self-lubricating friction-following restraint micro friction stir welding method, which is characterized in that a low-friction-coefficient auxiliary shaft shoulder rotating along with a stirring head is added outside the stirring head of the friction stir welding of a thin-wall component, the shaft shoulder is made of a self-lubricating material with certain high-temperature resistance, and the self-lubricating material is used for locally restraining the welded material and rolling the welded material after welding to keep the workpiece smooth before and after welding. Meanwhile, the auxiliary shaft shoulder can be used for adjusting and controlling the pressure or displacement of the workpiece, the auxiliary shaft shoulder and the stirring head rotate together, the problem of overlarge advancing resistance of the static shaft shoulder can be solved by adopting a welding mode without an inclination angle, and meanwhile, because the auxiliary shaft shoulder and the base metal have very small friction coefficient, the heat production quantity is low, the heat input in the welding process cannot be obviously increased, and the dynamic constraint effect on the thin-wall workpiece can be ensured without influencing the welding process. The invention can effectively solve the problems of difficult assembly, easy deformation and instability, large deformation after welding and the like in the friction stir welding process of the thin-wall member.)

1. The self-lubricating friction-with-welding restraint micro friction stir welding method is characterized in that an additional auxiliary shaft shoulder (3) is additionally arranged around a traditional micro friction stir welding stirring head (1), the shaft shoulder (3) and the stirring head (1) rotate together, the stirring head and the auxiliary shaft shoulder (3) move forward in a follow-up mode, a material (5) entering a stirring head area is restrained, and the surface rolling is carried out on the material at the rear part of the stirring head (1).

2. A method of self-lubricating welding-accompanied friction restraint micro friction stir welding according to claim 1, wherein the restraint of the auxiliary shoulder (3) to the workpiece (5) is a dynamic restraint, which is a restraint under the condition of friction, and the auxiliary shoulder (3) is made of self-lubricating material having a very low friction coefficient relative to aluminum alloy and capable of withstanding a certain high temperature.

3. The method for self-lubricating friction-with-weld restraint micro-friction stir welding according to claim 2, wherein the auxiliary shaft shoulder is made of heat-resistant plastic and composite materials thereof, and the heat-resistant temperature is more than or equal to 300 ℃.

4. The self-lubricating welding-following friction constraint micro friction stir welding method according to claim 1, wherein the welding process adopts a near-dip angle welding mode, the welding speed is 6000-; the shaft shoulder end surface (7) of the stirring head (1) adopts spiral line patterns suitable for non-dip angle welding, and the pattern depth is 0.2-0.4 mm.

5. The method for self-lubricating friction-constrained micro friction stir welding according to claim 1, wherein the auxiliary shoulder (3) is provided with a pressure regulating mechanism at the upper part, and the pressure regulating mechanism is composed of a spring (2) fixed on the stirring head (1), and the pressure provided by the spring (2) is 2-20 kg.

6. A method of self-lubricating friction-constrained micro friction stir welding according to claim 2, wherein the auxiliary shoulder (3) material is also embedded in the stir head (1) and is present as a part of the stir head and can be replaced according to the wear of the welding process.

7. The method for self-lubricating friction-constrained micro friction stir welding according to claim 1, wherein the connection interface (6) of the stirring head (1) and the auxiliary shoulder (3) adopts seamless fit, torque is specially transferred by means of symmetrical spacing rib groove fit, the stirring head (1) rotates and advances actively, and the auxiliary shoulder (3) rotates and advances with follow-up.

Technical Field

The invention relates to a self-lubricating welding-following friction constraint micro-friction stir welding method, and belongs to the field of welding.

Background

In the fields of aerospace, consumer electronics and the like, the welding of light materials such as aluminum alloy, magnesium alloy and the like with the wall thickness of about 1mm or below is widely required. However, due to the thin wall thickness, the conventional arc welding technology has large heat input, usually causes unstable deformation of materials, and is difficult to be qualified for welding the components. High-energy beam welding technology such as laser welding generally has a high forming defect incidence rate due to the problems of high reflectivity of aluminum alloy to laser, unstable molten pool and the like, and also limits the application of the connecting technology.

The friction stir welding technology is a solid phase connection technology, has the advantages of low heat input, small welding deformation, high welding quality and the like, and is widely applied to the fields of aerospace, rail vehicles, automobiles and electronics at present. For material connections with wall thicknesses of 1mm and below, the british welding institute (TWI) proposed the concept of micro friction stir welding, which uses a small-sized stir head and a high-speed spindle to achieve sufficient heat input to a small region of a thin-walled member. At present, the reliable connection of aluminum alloy butt joints with the wall thickness of 0.5mm or more can be realized by adopting a micro-stirring technology.

However, in practical engineering application, the core difficulty of the thin-wall member micro friction stir welding technology is found, and the original welding problem is changed into the welding assembly problem. Because a welding method with higher rotating speed and nearly no inclination angle is adopted in the micro friction stir welding process, the rotating and advancing action of the stirring head in the actual welding process generates higher acting force on the material to be welded; meanwhile, the thin-wall component has small self restraint degree, the material to be welded at the front end of the stirring head is easy to generate buckling deformation under the action of the acting force, and the material with local buckling deformation is higher than the shaft shoulder of the stirring head, so that the stirring head is scratched to damage the workpiece, and the connection cannot be realized.

Meanwhile, although friction stir welding has the characteristics of low heat transfer and small welding deformation, in the welding process of the thin-wall component, along with the reduction of the wall thickness of the plate, the local heating and cooling in the welding process still can cause remarkable welding deformation, and particularly after the welding tool is released, obvious deformation and even instability deformation are often generated. Aiming at the inherent characteristics of the thin plate welding process, a method for reducing the stress of a welding seam by welding and rolling is provided by a welder, and the method has certain effect.

In order to improve the assembly consistency of plates in the welding process and reduce the residual stress of a welded seam after welding, patent ZL200910071859.0 provides a method for assembling a circle of rolling steel balls around a stirring head to realize the rolling effect of the welded seam after welding so as to solve the problems of the residual stress, welding deformation and flash of the friction stir welding seam. However, this method is difficult to adapt to the micro friction stir welding process. On one hand, the micro friction stir welding process usually adopts a higher rotating speed, and under the rotating speed condition, the steel balls bear larger centrifugal force and are difficult to fix and stably work; on the other hand, under the high-speed condition, the dynamic balance of the additional pressing steel ball is difficult to realize, so that the high-speed instability caused by the dynamic balance can cause adverse effects on the welding process and bring about the safety problem; in addition, the steel balls compress the workpiece locally and discontinuously, and the workpiece is difficult to keep flat at the moment of contact with the stirring head. In addition, the steel balls have high hardness, are in rigid contact with the surface of a workpiece, and are easy to damage the workpiece and the surface of a welding seam.

Disclosure of Invention

In order to solve the practical engineering problems and the defects of the existing method, the invention provides the micro friction stir welding method adopting self-lubricating friction constraint along with welding, which can realize the maintenance of the flatness of the workpiece before welding and the reduction of the residual stress of a welding seam to a certain extent, solve the problems of difficult assembly of the welding workpiece in the friction stir welding process of the thin-wall component, welding failure caused by deformation in the welding process and the like, and effectively realize the high-reliability and high-efficiency welding of the thin-wall component.

The invention mainly comprises that on the basis of the traditional friction stir welding method, the inclination-free high-speed friction stir welding is carried out by adopting a self-lubricating and welding-following friction constraint method, a self-lubricating material with extremely low friction coefficient relative to aluminum alloy is adopted as an auxiliary shaft shoulder, and the auxiliary shaft shoulder is tightly sleeved on a stirring head and rotates and advances together with the stirring head. The stirring head and the auxiliary shaft shoulder move forward along with the stirring head, so that materials entering the stirring head area are restrained, and the surface rolling is carried out on the materials at the rear part of the stirring head.

Furthermore, the auxiliary shaft shoulder is a dynamic restraint for the workpiece under the condition of friction, and adopts a self-lubricating material which has a very low friction coefficient relative to the aluminum alloy and can resist a certain high temperature.

Preferably, the auxiliary shaft shoulder is made of heat-resistant plastic and composite materials thereof, and the heat-resistant temperature is more than or equal to 300 ℃.

Furthermore, a welding mode with a nearly non-inclination angle is adopted in the welding process, the welding speed is 6000-10000rpm, the auxiliary shaft shoulder and the stirring head are designed in a shape gradually protruding from outside to inside, the end face of the shaft shoulder of the auxiliary shaft shoulder is in smooth contact with the base material, and the outer diameter of the auxiliary shaft shoulder is 20-50 mm; the shaft shoulder end surface of the stirring head adopts spiral line patterns suitable for non-dip angle welding, and the pattern depth is 0.2-0.4 mm.

Furthermore, the welding process adopts a nearly non-inclination angle welding mode, the welding speed is 6000-10000rpm, the auxiliary shaft shoulder and the upper part of the auxiliary shaft shoulder are provided with a pressure regulating mechanism which is composed of a spring fixed on the stirring head, and the pressure provided by the spring is 2-20 kg.

Further, the auxiliary shoulder material may also be embedded on the pin, present as part of the pin, and may be replaced as a function of wear during welding.

Furthermore, the connection interface of the stirring head and the auxiliary shaft shoulder adopts seamless fit, torque is specially transmitted in a symmetrical limiting rib groove fit mode, the stirring head rotates and advances actively, and the auxiliary shaft shoulder rotates and advances in a follow-up mode.

Meanwhile, the auxiliary stirring shaft shoulder adopts the shape design from outside to inside to be convex to smooth contact, the stirring head shaft shoulder adopts the shape design with an inwards concave spiral line, and the outer edge also adopts the shape from outside to inside to be convex. On the upper part of the auxiliary shaft shoulder, a pressure compensation control device can be arranged, so that the adjustable control of the auxiliary shaft shoulder on the surface pressure of a workpiece can be ensured, meanwhile, the material lost due to friction can be compensated, and the auxiliary shaft shoulder wear-out compensation device is suitable for the condition of long-distance welding auxiliary shaft shoulder wear. In addition, the invention also comprises another relatively simple case, namely, a method for embedding the self-lubricating material outside the shaft shoulder of the traditional stirring head, the method utilizes the elasticity and the scalability of the self-lubricating material to provide continuous pressure restraint, and the welding process is suitable for welding at a short distance.

The invention has the following advantages: the welding method has the advantages that the auxiliary shaft shoulder continuously rotates and advances under dynamic rotation, so that the welding advancing resistance can be greatly reduced relative to a static shaft shoulder, the continuous dynamic constraint on the material to be welded in a welding area is realized, and the welding failure caused by the fact that the material at the front end of the stirring head is protruded and deformed during welding, and cannot enter a working area of the stirring head; the auxiliary shaft shoulder has an extremely low friction coefficient to the aluminum alloy material, so that the friction heat generation between the auxiliary shaft shoulder and the surface of the base metal is low, and the heat input in the welding process and the torque consumption of a welding main shaft cannot be obviously increased; thirdly, the method can also realize continuous compaction and shape correction of the welded seam surface, and the shape correction of the welded material in a hot state in real time along with welding can reduce the deformation after welding; and fourthly, the method adopts a non-dip angle welding means, and can realize high-speed welding of the two-dimensional curve welding seam.

Drawings

FIG. 1 is a schematic diagram of a self-lubricating friction-constrained micro friction stir welding method according to an embodiment of the present invention;

fig. 2 is a schematic diagram of another embodiment of the present invention.

Detailed Description