CN110681983A - Bottom convex stirring head for friction stir welding - Google Patents

Abstract

The invention discloses a bottom convex stirring head for friction stir welding, which comprises a clamping part, a shaft shoulder part and a stirring needle which are sequentially connected, wherein the bottom of the needle tip of the stirring needle is provided with a boss for increasing the flow of bottom softened metal and reducing the migration resistance of the bottom softened metal. The stirring head has the advantages of simple and reliable structure, capability of reducing the migration resistance of softened metal at the bottom, capability of preventing grooves and forming good welding seams.

Description

Convex stirring head for friction stir welding

technical field

The invention mainly relates to friction stir welding technology, in particular to a bottom convex stirring head for friction stir welding.

Background technique

In the process of friction stir welding, the interaction between the stirring head and the workpiece material generates heat, which heats the workpiece material around the stirring head to a plasticized state to form a weld. The heat mainly includes the friction between the shaft shoulder and the stirring needle and the base metal. Heat generation and plastic deformation heat generated by stirring and extrusion of workpiece materials. In the process of friction stir welding, the distribution of the temperature field of the workpiece is not uniform, showing the law that the temperature at the shoulder of the stirring head is the highest and decreases in turn on the end face of the stirring needle.

The stirring head is the core of friction stir welding technology. It interacts with the workpiece to be welded to realize the connection of the welded material.

There is no mature theory for the size design of the stirring head. Most of the designs are based on experience. The stirring head is mainly composed of a stirring needle, a shaft shoulder and a clamping area. The stirring needle is located on the top of the stirring head and has different shapes. The stirring needle generates some heat energy through rotating friction. The main function of the stirring needle is similar to that of a pump. It can make the metal in a highly plasticized state flow from front to back along the stirring needle while maintaining the up and down movement, passing through the shaft of the stirring head. Shoulder forging and cooling to form joints. The size of the stirring needle determines the size and welding speed of the weld nugget area of the weld; on the one hand, the shape of the stirring needle determines the heating method and the upsetting mode of the plastic material during the welding process, and on the other hand directly affects the weld area. The flow pattern of softened material plays an important role in joint forming. The shape and size of the stirring needle and the related welding process parameters together determine the heat generation and material flow during the welding process, which ultimately determines the quality of the friction stir welded joint.

Generally speaking, the stirring needle adopts a cylindrical or conical design. Due to different workpiece materials, different structures, and different thicknesses of workpiece materials, the stirring needle adopts a general structure design. Under many working conditions, the plasticized metal cannot be fully stirred and moved, which will cause hole defects in the weld, and even produce serious surface grooves. groove.

During the welding process of the ordinary stirring head, because the bottom of the needle tip is small and the end face is flat, the stirring force generated is small, which is not conducive to the flow filling of the bottom material, and it is easy to generate groove lines at the bottom, which is not conducive to forming a good weld. It has a certain adverse effect on the quality of the weld.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, and to provide a bottom convex type for friction stir welding, which has a simple and reliable structure, can reduce the migration resistance of the softened metal at the bottom, can prevent grooves and form a good weld. Stirrer.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions:

A bottom-convex stirring head for friction stir welding, comprising a clamping part, a shaft shoulder and a stirring needle connected in sequence, the stirring needle is provided at the bottom of its needle tip for increasing the flow of softened metal at the bottom and reducing the bottom Bosses that soften metal migration resistance.

As a further improvement of the above technical solution:

The axis of the stirring needle is defined as the rotation center line, and the bottom outline of the boss is defined as the rotation generatrix, and the boss is formed by the rotation generatrix rotating one circle around the rotation centerline.

The vertical line defining the contact point between the boss and the weldment is the welding line. During welding, the welding line and the rotation center line form an included angle a, 1°≤a≤5°.

Define the diameter of the bottom of the needle tip as L1, define the diameter of the boss as L2, and L1/10≤L2≤L1.

Define the height of the boss as h, L1/70≤h≤L1/7.

The bottom outline of the boss is a smooth transition convex arc line.

The bottom outline of the boss is formed by connecting the oblique line on the peripheral side and the convex arc line in the middle.

The bottom outline of the boss is formed by connecting a circular arc line convex on the peripheral side and a horizontal straight line in the middle.

The bottom outline of the boss is formed by connecting a vertical straight line on the peripheral side and a convex circular arc line in the middle.

The bottom outline of the boss is formed by connecting a concave circular arc on the peripheral side and a central convex circular arc.

Define the diameter of the circular arc line that is convex in the middle as L3, define the diameter of the bottom of the needle tip as L1, and L1/10≤L3≤L1/2.

Compared with the prior art, the advantages of the present invention are:

The bottom convex stirring head for friction stir welding of the present invention comprises a clamping part, a shoulder part and a stirring needle which are connected in sequence. Migration resistance bosses. During welding, the clamping part is used for clamping, the stirring needle generates heat energy through rotational friction, and the shoulder part is used to form the forging. Compared with the traditional structure, the stirring head is formed with a boss at the bottom of the needle tip. During the welding process, the boss increases the flow of the softened metal at the bottom, reduces the migration resistance of the softened metal at the bottom, and optimizes the contact between the stirring head. The stability and insertion resistance of the to-be-welded parts are beneficial to the flow filling of the bottom material, and it is difficult to generate grooves at the bottom, which is conducive to the formation of a good welding seam, and the structure is simple and reliable.

Description of drawings

FIG. 1 is a schematic three-dimensional structure diagram of Embodiment 1 of the present invention.

FIG. 2 is a schematic structural diagram of a front view of Embodiment 1 of the present invention.

FIG. 3 is a partial enlarged structural schematic diagram of Embodiment 1 of the present invention.

FIG. 4 is a partial enlarged schematic view of the structure (in use state) of Embodiment 1 of the present invention.

5 is a schematic structural diagram of a boss in Embodiment 1 of the present invention.

6 is a schematic structural diagram of a boss in Embodiment 2 of the present invention.

7 is a schematic structural diagram of a boss in Embodiment 3 of the present invention.

8 is a schematic structural diagram of a boss in Embodiment 4 of the present invention.

FIG. 9 is a schematic structural diagram of a boss in Embodiment 5 of the present invention.

The symbols in the figure represent:

1. Clamping part; 2. Shaft shoulder; 3. Stirring needle; 31. Needle tip; 32. Boss; 321. Rotating busbar; 322. Welding line;

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

Example 1:

Figures 1 to 5 show the first embodiment of the bottom-convex stirring head for friction stir welding according to the present invention, comprising a clamping part 1, a shoulder part 2 and a stirring needle 3 connected in sequence, and the stirring needle 3 is in the The bottom of the needle tip 31 is provided with a boss 32 for increasing the flow of the softened metal at the bottom and reducing the migration resistance of the softened metal at the bottom. During welding, the clamping part 1 is used for clamping, the stirring needle 3 generates thermal energy through rotational friction, and the shoulder part 2 is used to form forging. Compared with the traditional structure, the stirring head is formed with a boss 32 at the bottom of the needle tip 31. During the welding process, the boss 32 increases the flow of the softened metal at the bottom, reduces the migration resistance of the softened metal at the bottom, and optimizes stirring. The stability and insertion resistance of the head when it is in contact with the part to be welded is favorable for filling the bottom material, and it is not easy to generate grooves at the bottom, which is favorable for forming a good welding seam, and the structure is simple and reliable.

In this embodiment, the axis of the stirring needle 3 is defined as the rotation centerline 33 , the bottom outline of the boss 32 is defined as the rotation generatrix 321 , and the boss 32 is formed by the rotation generatrix 321 rotating around the rotation centerline 33 once. The boss 32 is formed into an integrated structure with the needle tip 31 by a rotation of the rotating generatrix 321 around the rotation center line 33 once, which improves the overall strength.

In this embodiment, the vertical line defining the contact point between the boss 32 and the weldment is the welding line 322. During welding, the welding line 322 and the rotation center line 33 form an included angle a, 1°≤a≤5°. During welding, the stirring needle 3 is at a certain inclination angle, that is, the welding line 322 and the rotation center line 33 are at an included angle a. This setting makes it more conducive to the flow and filling of the bottom material when moving in the welding direction, thereby forming a good weld. In this embodiment, a is set to 4°.

In this embodiment, the diameter of the bottom of the needle tip 31 is defined as L1, the diameter of the boss 32 is defined as L2, and L1/10≤L2≤L1. In this structure, the diameter L2 of the boss 32 is smaller than the diameter L1 of the bottom of the needle tip 31, that is, a space is formed on the periphery of the boss 32 to reduce the migration resistance of the welded plasticizing material at the bottom, and the setting of L1/10≤L2 also The strength of the boss 32 can be ensured and the service life can be improved. In this embodiment, L2=L1/3.

In this embodiment, the height of the boss 32 is defined as h, and L1/70≤h≤L1/7. The design of the height h of the boss 32 is mainly to ensure the reasonable surrounding space of the boss 32. If the height h is too high, it will increase the fluidity of the welding plasticized material, which is not conducive to the flow filling of the bottom material; if the height h is too low, it will To increase the migration resistance of the welding plasticized material, through the setting of L1/70≤h≤L1/7, the flow filling of the bottom material and the reduction of the migration resistance can be taken into account, and the structure is simple and the design is ingenious. In this embodiment, h=L1/20.

In this embodiment, the bottom contour line of the boss 32 is a smooth transition convex arc line. Its structure is simple and easy to form.

Example 2:

As shown in FIG. 6 , the second embodiment of the bottom convex type stirring head used for friction stir welding of the present invention is basically the same as that of the first embodiment, the only difference is: in this embodiment, the bottom of the boss 32 is The outer contour line is formed by the connection of the oblique line on the peripheral side and the convex arc line in the middle. Its structure is simple and easy to form.

Example 3:

As shown in FIG. 7 , the third embodiment of the bottom convex type stirring head used for friction stir welding of the present invention is basically the same as that of the first embodiment, the only difference is that in this embodiment, the bottom of the boss 32 is The outer profile is formed by connecting a circular arc line convex on the peripheral side and a horizontal straight line in the middle. Its structure is simple and easy to form.

Example 4:

As shown in FIG. 8 , the fourth embodiment of the bottom-convex stirring head used for friction stir welding of the present invention is basically the same as that of the first embodiment, the only difference being: in this embodiment, the bottom of the boss 32 is The outer profile is formed by the connection of the vertical straight line on the peripheral side and the convex circular arc line in the middle. Its structure is simple and easy to form.

Example 5:

As shown in FIG. 9 , the fifth embodiment of the bottom-convex stirring head for friction stir welding according to the present invention is basically the same as that of the first embodiment, except that in this embodiment, the bottom of the boss 32 is The outer contour line is formed by connecting the concave circular arc line on the peripheral side and the convex circular arc line in the middle. Its structure is simple and easy to form.

In this embodiment, the diameter of the circular arc line that is convex in the middle is defined as L3, and the diameter of the bottom of the needle tip 31 is defined as L1, where L1/10≤L3≤L1/2. In this structure, the diameter L2 of the boss 32 is smaller than the diameter L1 of the bottom of the needle tip 31, even if a space is formed on the periphery of the boss 32 to reduce the migration resistance of the welding plasticizing material, and the setting of L1/10≤L2 can The strength of the boss 32 is ensured, and the service life is improved. In this embodiment, L2=L1/3.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, can make many possible changes and modifications to the technical solution of the present invention by using the technical content disclosed above, or modify it into an equivalent implementation of equivalent changes. example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention should fall within the protection scope of the technical solutions of the present invention.

Claims (11)

1. A bottom convex stirring head for friction stir welding, comprising a clamping part (1), a shaft shoulder (2) and a stirring needle (3) connected in sequence, characterized in that: the stirring needle (3) ) at the bottom of its needle tip (31) is provided with a boss (32) for increasing the flow of the bottom softened metal and reducing the migration resistance of the bottom softened metal. 2. The bottom-convex stirring head for friction stir welding according to claim 1, characterized in that: the axis of the stirring needle (3) is defined as the rotation center line (33), and the bottom outside of the defined boss (32) The profile line is a rotating generatrix (321), and the boss (32) is formed by one rotation of the rotating generatrix (321) around the rotation center line (33). 3. The bottom-convex stirring head for friction stir welding according to claim 2, wherein the vertical line defining the contact point between the boss (32) and the weldment is the welding line (322), and during welding, The welding line (322) and the rotation center line (33) form an included angle a, 1°≤a≤5°. 4. The bottom-convex stirring head for friction stir welding according to claim 3, characterized in that: the diameter of the bottom of the needle tip (31) is defined as L1, the diameter of the boss (32) is defined as L2, and L1/10 ≤L2≤L1. 5 . The bottom-convex stirring head for friction stir welding according to claim 4 , wherein the height of the boss ( 32 ) is defined as h, and L1/70≦h≦L1/7. 6 . 6. The bottom-convex stirring head for friction stir welding according to any one of claims 1 to 5, wherein the bottom outline of the boss (32) is a smooth transition outer convex circle arc. 7. The bottom convex type stirring head for friction stir welding according to any one of claims 1 to 5, characterized in that: the bottom outline of the boss (32) is formed by the oblique line on the peripheral side and the The middle convex arc line is connected to form. 8. The bottom-convex stirring head for friction stir welding according to any one of claims 1 to 5, characterized in that: the bottom outline of the boss (32) is formed by a circle that is convex on the peripheral side The arc and the horizontal straight line in the middle are connected to form. 9. The bottom-convex stirring head for friction stir welding according to any one of claims 1 to 5, characterized in that: the bottom outline of the boss (32) is defined by a vertical line on the peripheral side It is formed by connecting with a convex arc line in the middle. 10. The bottom-convex stirring head for friction stir welding according to any one of claims 1 to 5, characterized in that: the bottom outline of the boss (32) is a circle with a concave on the peripheral side The arc line and the middle convex arc line are connected to form. 11. The bottom-convex stirring head for friction stir welding according to claim 10, characterized in that: the diameter of the circular arc line that defines the middle outer convexity is L3, and the diameter of the bottom of the needle tip (31) is defined as L1, L1 /10≤L3≤L1/2.

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