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CN-119304341-B - Friction stir welding method

CN119304341BCN 119304341 BCN119304341 BCN 119304341BCN-119304341-B

Abstract

The invention relates to a friction stir welding method, which comprises a stirring head, wherein the stirring head comprises a shaft shoulder and a stirring pin, the stirring pin is arranged at the lower end of the shaft shoulder, and the stirring head with the shaft shoulder diameter of 5.5mm and the stirring pin length of 1.4mm is designed by the method and welded at the rotating speed of 1500rpm and the welding speed of 200mm/s, so that the welding quality, the production efficiency and the material utilization rate can be improved.

Inventors

  • SHEN MINGSHAN

Assignees

  • 东莞市发斯特精密科技股份有限公司

Dates

Publication Date
20260508
Application Date
20241128

Claims (5)

  1. 1. The friction stir welding method is characterized by comprising a stirring head, wherein the stirring head comprises a shaft shoulder and a stirring pin, and the stirring pin is arranged at the lower end of the shaft shoulder; The design method of the shaft shoulder radius comprises the following steps: A1, in the stirring welding process, the stirring head is used for stably welding the workpiece vertically so as to form a plastic flow area and a solid area on the workpiece, a separation line between the plastic flow area and the solid area is taken as an isotherm, the isotherm is approximately regarded as a parabola, a rectangular coordinate system is established by taking the lowest point of the parabola as an origin, and then the equation of the parabola satisfies the following relation: 1 (1) A2, according to the total heat Q generated when the stirring head vertically and stably welds the workpiece, the total heat Q comprises shaft shoulder friction heat generation Q 1 , stirring pin friction heat generation Q 2 and material on the side surface of the stirring pin which generate heat Q 3 due to plastic deformation, and Q 3 Q 1 ,Q 3 Q 2 , so q=q 1 +Q 2 , and Q, Q 1 、Q 2 satisfies the following relation: 2, 2 3 4. The method is to Wherein eta is the heat input efficiency, mu is the friction coefficient, omega is the rotating speed, tau is the pressure intensity of the contact surface of the shaft shoulder of the stirring head and the workpiece, r is the diameter of the shaft shoulder, Is the diameter of the stirring pin; A3, on an isotherm, the friction heat generation amount of the stirring head is equal to the heat dissipation amount of an approximate critical heat dissipation surface in the material, and the following results: 5. The method is to Wherein, the For the purpose of the heat input power, The heat dissipation power is used; A4, the friction heat production Q 1 of the shaft shoulder accounts for 85 percent of the total friction heat production Q of the stirring head, so that the stirring head has 6. The method is to 7. The method of the invention Wherein lambda is the heat conductivity of the material, l is the thickness of the interface, deltaT is the temperature difference at two sides of the interface, A is the area of the paraboloid, and the method can be used for obtaining: 8. The method is used for preparing the product In addition, according to the parabolic equation, when There is z=h, where h is the thickness of the workpiece, so there is 9. The invention is applicable to The comprehensive results of 1-9 show that the shaft shoulder radius r and the workpiece thickness h meet the following relation: 10. The method of the invention Where λ is the thermal conductivity of the material, l is the thickness of the interface, η is the heat input efficiency, μ is the coefficient of friction, τ is the workpiece contact surface pressure, ω is the rotational speed.
  2. 2. The friction stir welding method of claim 1 wherein said pin length design method comprises the steps of: the length of the stirring pin is as follows: 11. The method of the invention Wherein, the For the length of the stirring pin, For the thickness of the work piece, In order for the stirring head to be depressed to a depth, Is the distance between the bottom end of the stirring pin and the bottom surface of the workpiece.
  3. 3. The friction stir welding method of claim 2 wherein the angle of inclination of the stirring head to the direction perpendicular to the surface of the workpiece is 1-5 °.
  4. 4. A friction stir welding method according to claim 3 wherein the material of the stirring head is made of W360.
  5. 5. The friction stir welding method of claim 4 including the steps of: b1, inserting a stirring pin into the welded plate at a speed of 30 mm/min; B2, the insertion residence time is 8-10s; b3, after the welding is finished, the stirring pin withdraws the welded plate from the molten pool at the speed of 100 mm/min; b4, back-pumping the residence time for 2s.

Description

Friction stir welding method Technical Field The invention relates to the technical field of friction welding, in particular to a friction stir welding method. Background The mobile phone middle frame is used for protecting the similar shell of the mobile phone, only has a similar frame, and needs to be processed by using a CNC (computer numerical control) machine tool, however, the existing CNC processing method is long in working hours and low in efficiency, and is difficult to process a fine structure, and a CNC process and a die casting process are combined through a friction stir welding process according to the problems. Friction stir welding refers to the process of using heat generated by friction between a welding tool rotating at a high speed and a workpiece to locally melt a welded material, and when the welding tool moves forwards along a welding interface, the plasticized material flows from the front part to the rear part of the welding tool under the action of the rotating friction force of the welding tool, and a compact solid-phase welding seam is formed under the extrusion of the welding tool. However, the thickness of the mobile phone middle frame is thinner, so that the conventional stirring head is easy to deform the mobile phone middle frame, the welding passing rate is affected, and the manufacturing cost is increased. Disclosure of Invention The invention mainly aims to provide a friction stir welding method which aims to solve the technical problems and improve welding quality, production efficiency and material utilization rate. In order to achieve the above purpose, the invention adopts the following technical scheme: The friction stir welding method comprises a stirring head, wherein the stirring head comprises a shaft shoulder and a stirring pin, and the stirring pin is arranged at the lower end of the shaft shoulder; The design method of the shaft shoulder radius comprises the following steps: A1, in the stirring welding process, the stirring head is used for stably welding the workpiece vertically so as to form a plastic flow area and a solid area on the workpiece, a separation line between the plastic flow area and the solid area is taken as an isotherm, the isotherm is approximately regarded as a parabola, a rectangular coordinate system is established by taking the lowest point of the parabola as an origin, and then the equation of the parabola satisfies the following relation: z=α (x 2+y2) 1 A2, according to the total heat Q generated when the stirring head is used for stably welding the workpiece vertically, the total heat Q comprises shaft shoulder friction heat generation Q 1, stirring pin friction heat generation Q 2 and materials on the side face of the stirring pin, wherein the materials generate heat Q 3 due to plastic deformation, and Q 3＜＜Q1,Q3＜＜Q2, so that Q=Q 1+Q2 and Q, Q 1、Q2 satisfy the following relation: wherein eta is the heat input efficiency, mu is the friction coefficient, omega is the rotating speed, tau is the pressure intensity of the contact surface of the shaft shoulder of the stirring head and the workpiece, r is the diameter of the shaft shoulder, and r da is the diameter of the stirring pin; A3, on an isotherm, the friction heat generation amount of the stirring head is equal to the heat dissipation amount of an approximate critical heat dissipation surface in the material, and the following results: Q in＝Qdis type 5 Wherein, Q in is heat input power, and Q dis is heat dissipation power; A4, the friction heat production Q 1 of the shaft shoulder accounts for about 85 percent of the total friction heat production Q of the stirring head, so that the stirring head has Q in = Q x 1.17, 6 Q dis = λ/l·Δt·a 7 Wherein lambda is the heat conductivity of the material, l is the thickness of the interface, deltaT is the temperature difference at two sides of the interface, A is the area of the paraboloid, and the method can be used for obtaining: In addition, according to the parabolic equation, when x 2+y2＝r2, there is z=h, where h is the thickness of the workpiece, there is A=h/r 2 type 9 The comprehensive results of 1-9 show that the shaft shoulder radius r and the workpiece thickness h meet the following relation: where λ is the thermal conductivity of the material, l is the thickness of the interface, η is the heat input efficiency, μ is the coefficient of friction, τ is the workpiece contact surface pressure, ω is the rotational speed. As a preferable technical scheme, the stirring pin length design method comprises the following steps: the length of the stirring pin is as follows: h pin＝Hw-(Hplunge+Hf) type 11 Wherein H pin is the length of the stirring pin, H w is the thickness of the workpiece, H plunge is the pressing depth of the stirring head, and H f is the distance from the bottom end of the stirring pin to the bottom surface of the workpiece. As a preferable technical scheme, the inclination angle of the stirring head and the direction vertic