CN115740726B - Floating friction stir welding device and method for realizing self-repairing by solid-phase material addition - Google Patents

Abstract

A floating friction stir welding device and a method for realizing self-repairing by solid-phase material addition relate to a floating friction stir welding device and a method. The invention aims to solve the problem of reduced yield of welded workpieces caused by the defects of weld thinning, flash, key holes and the like in the friction stir welding process. The device comprises a main shaft, a shaft sleeve, a relative position adjusting mechanism, a sleeve and an additive stirring head; the shaft sleeve is arranged on the upper surface of the relative position adjusting mechanism, the sleeve is arranged on the lower surface of the relative position adjusting mechanism, the upper part of the material adding stirring head is inserted into the lower end of the sleeve from bottom to top, the lower part of the main shaft is inserted into the upper end of the shaft sleeve from top to bottom, and the lower end of the main shaft is fixedly connected with the upper end of the material adding stirring head. The invention belongs to the technical field of solid-phase additive manufacturing.

Description

A floating friction stir welding device and method for realizing self-repair by solid phase addition

technical field

The invention relates to a floating friction stir welding device and method, belonging to the technical field of solid-phase additive manufacturing.

Background technique

Additive manufacturing technology, also known as 3D printing, is a "bottom-up" method that accumulates materials layer by layer to achieve a technological process from scratch. The additive manufacturing process integrates material processing and molding technology, computer model building technology, etc., and realizes integrated molding of complex construction through programs and numerical control systems.

Friction stir welding technology is a solid phase connection technology, which refers to the use of heat generated by the friction between the high-speed rotating welding tool and the workpiece to locally melt the welded material. When the welding tool moves forward along the welding interface, the plasticized material Under the action of the rotational friction of the welding tool, it flows from the front of the welding tool to the rear, and forms a dense solid-phase weld under the extrusion of the welding tool. It has the advantages of low welding temperature, large plastic deformation, fine grains in the welding area, and high mechanical properties. It is suitable for high-performance connections of light alloys such as aluminum alloys. At the same time, compared with the traditional fusion welding technology, friction stir welding does not have defects such as pores and cracks, and the post-weld deformation and residual stress are small. However, friction stir welding also has certain limitations: weld thinning, flash, keyholes and holes, etc. Due to excessive welding pressure, more plastic material is extruded from both sides of the shoulder, and flash defects are formed on the surface of the weld after cooling. The formation of flash defects in turn leads to weld thinning. At the end of welding, when the stirring needle lifts out the workpiece, a keyhole is formed at the end of the weld seam, and it is difficult to repair the weld seam. Finally, the formation of void defects is mainly due to insufficient material flow to the plasticized state due to insufficient frictional heat input during the welding process, resulting in insufficient material flow, thus resulting in the phenomenon that the weld zone is not completely closed. The joint is prone to holes due to insufficient friction of the stirring needle. We usually find such defects in the middle and lower part of the forward side of the joint and near the surface of the weld. At the same time, the holes located near the surface of the weld in line with the welding direction are also called tunnel defects when they extend longer in the direction of the weld length.

Contents of the invention

In order to solve the problem that the yield of welded workpieces decreases due to the existence of weld seam thinning, flash, keyhole and other defects in the process of friction stir welding, the invention further proposes a floating friction stir welding that realizes self-repair by solid phase addition Welding apparatus and methods.

The technical solution adopted by the present invention to solve the above problems is: the welding device of the present invention includes a main shaft, a shaft sleeve, a relative position adjustment mechanism, a sleeve and an additive stirring head; the shaft sleeve is installed on the upper surface of the relative position adjustment mechanism , the sleeve is installed on the lower surface of the relative position adjustment mechanism, the upper part of the additive stirring head is inserted into the lower end of the sleeve from bottom to top, the lower part of the main shaft is inserted into the upper end of the sleeve from top to bottom, and the lower end of the main shaft It is fixedly connected with the upper end of the additive stirring head.

Further, the relative position adjustment mechanism includes an upper saddle, a right support arm assembly, a connecting rod, a transmission screw, a left support arm assembly and a lower saddle; the upper saddle and the lower saddle are arranged in sequence from top to bottom, and the upper The right end of the saddle is connected with the right end of the lower saddle through the right support arm assembly, the left end of the upper saddle is connected with the left end of the lower saddle through the left support arm assembly, the left end of the connecting rod is connected with the left support arm assembly, and the drive screw The right end is connected with the right support arm assembly, the right end of the connecting rod is connected with the left end of the transmission screw, the lower surface of the bushing is fixedly connected with the upper surface of the upper saddle, and the upper surface of the sleeve is fixedly connected with the lower surface of the lower saddle .

Further, the relative position adjustment mechanism further includes a thrust bearing, and the left end of the transmission screw is rotatably connected to the right end of the connecting rod through the thrust bearing.

Further, the right support arm assembly includes a right upper support arm, a right lower support arm and a lead screw nut; the upper end of the right upper support arm is rotationally connected with the right end of the upper saddle, and the lower end of the right upper support arm is rotationally connected with the lead screw nut, and the right lower support arm The upper end of the arm is rotatably connected with the lead screw nut, the lower end of the lower right support arm is rotatably connected with the right end of the lower saddle, and the right end of the transmission lead screw is inserted in the lead screw nut.

Further, the left support arm assembly includes a left upper support arm, a left lower support arm and a connecting piece; the upper end of the left upper supporting arm is rotatably connected with the left end of the upper saddle, the lower end of the left upper support arm is rotatably connected with the connecting piece, and the upper end of the left lower support arm is rotatably connected with the left end of the upper saddle. The connecting piece is rotatably connected, and the lower end of the left lower support arm is rotatably connected with the left end of the lower saddle.

Further, the sleeve includes a first positioning platform and a shaft shoulder; the upper end of the shaft shoulder is fixedly connected with the middle part of the lower surface of the first positioning platform, and the shaft shoulder is provided with a material storage chamber that runs through the upper end surface and the lower end surface of the shaft shoulder. The middle part of the upper surface of the first positioning platform has a through hole, and the through hole communicates with the material storage chamber, and the upper surface of the first positioning platform is symmetrically wiped with two positioning holes, and the outer wall of the upper end of the shaft shoulder is provided with a wire inlet, and The wire inlet is communicated with the material storage chamber, and the upper surface of the first positioning platform is fixedly connected with the lower surface of the lower saddle.

Further, the additive mixing head includes a clamping surface, a second positioning platform, a broken wire blade, a variable pitch thread segment and a three-milling plane stirring needle; a clamping surface, a second positioning platform, a broken wire blade, a variable pitch thread segment and The stirring pins with three milling planes are sequentially connected into one body from top to bottom, and the clamping surface is fixedly connected with the lower end of the main shaft.

Further, the stirring needle with three milling planes is a tapered needle structure with three milling planes.

The concrete steps of welding method of the present invention are as follows:

Step 1. Feed the filamentary additive material into the sleeve through the wire inlet;

Step 2. The additive raw material is cut off by the broken wire blade, and then it is stirred, rubbed and conveyed by the variable-pitch thread to realize continuous downward movement and accumulation;

Step 3. The stirring pin of the third milling plane rotates at high speed and plunges into the butt workpiece, so that a closed space is formed between the weld seam and the shaft shoulder;

Step 4. Under the continuous rotation of the additive mixing head, the granular additive raw material is gradually transformed into a thermoplastic state under high temperature and high pressure in the closed sleeve;

Step 5. While the additive stirring head is moving along the weld seam, the gap between the thermoplastic additive raw material shoulder and the weld seam is additively formed to realize the repair of thinning, an inherent defect of friction stir welding, and to improve the gap of the butt joint tolerance;

Step 6. At the end of welding, when the main shaft drives the additive stirring head to move up, the relative position adjustment mechanism between the bushing and the sleeve starts to operate, and the motor drives the transmission screw to rotate, and then drives the right support arm assembly and The left support arm assembly is opened, and finally the relative movement between the sleeve and the additive mixing head is realized, that is, the shaft shoulder and the workpiece remain relatively stationary;

Step 7. When the lower plane of the three-milling plane stirring needle reaches the horizontal position of the shaft shoulder, the relative position adjustment mechanism stops running and moves up together with the main shaft, and the self-repairing welding process ends.

The beneficial effects of the present invention are:

1. The present invention can realize continuous wire feeding, realize continuous material-adding welding without stopping the machine, and can work continuously for a long time to obtain welding workpieces with thickened and widened weld seams. Holes and cracks ensure the yield rate, greatly improve production efficiency, and have good economic applicability;

2. This method realizes the repair of the thinning of the weld seam caused by flashing caused by excessive shoulder pressure and the repair of the residual keyhole caused by the extraction of the stirring needle through the wire-filled additive welding process, reducing The geometric mutation of the weld structure is reduced, the stress concentration is reduced, and the mechanical properties and fatigue strength of the weld are comprehensively improved;

3. The method can improve the gap tolerance of the butt joint, reduce the need for surface treatment before welding, overcome the inherent limitations of the existing friction stir welding technology, broaden the application range of the friction stir welding technology and improve production efficiency;

4. The present invention has a wide range of applications, and can be applied to butt joints and lap joints of various metals and alloys; at the same time, the design of multiple wire feed channels on the wire feed device of the present invention can realize uninterrupted synchronization from homogeneous wire materials to heterogeneous materials Wire feeding, can design solid-phase additive manufacturing shaped parts with integrated structure, composition and function;

5. The present invention adopts a broken wire blade with a variable pitch thread structure, which can realize the process of the welding wire from the solid phase through crushing, extrusion and transmission to the thermoplastic state without forming a liquid phase.

Description of drawings

Fig. 1 is the overall structural representation of the present invention;

Fig. 2 is a front structural schematic view of the left support arm assembly and the right support arm assembly;

Fig. 3 is a top view structure diagram of the left support arm assembly and the right support arm assembly;

Fig. 4 is a top view of the connection structure between the connecting rod and the transmission screw;

Figure 5 is a top view of the sleeve;

Fig. 6 is a sectional view along A-A in Fig. 5;

Fig. 7 is a structural schematic diagram of an additive mixing head.

Detailed ways

Specific Embodiment 1: This embodiment is described with reference to FIG. 1 . A floating friction stir welding device for self-repairing by solid-phase additives described in this embodiment includes a main shaft 1 , a shaft sleeve 2 , a relative position adjustment mechanism, and a sleeve 8 and the additive material stirring head 9; the shaft sleeve 2 is installed on the upper surface of the relative position adjustment mechanism, the sleeve 8 is installed on the lower surface of the relative position adjustment mechanism, and the upper part of the additive material mixing head 9 is inserted into the sleeve from bottom to top In the lower end of the barrel 8, the lower part of the main shaft 1 is inserted into the upper end of the sleeve 2 from top to bottom, and the lower end of the main shaft 1 is fixedly connected with the upper end of the additive mixing head 9.

The relative position adjustment mechanism is used to realize the adjustment of the relative position of the axle sleeve and the sleeve. The adjustment process is as follows: the motor drives the transmission screw 6 to rotate, the screw nut 403 moves to the left under the transmission of the transmission screw 6, and the upper right support arm 401 and the lower right support arm 402 are opened, and at the same time, the connecting piece 703 is pulled to the right by the action of the connecting rod 5, and the upper left support arm 701 and the lower left support arm 702 are opened simultaneously, so that the upper saddle 3 and the lower saddle 11 are opposite to each other. Movement, and then realize the relative movement of the shaft sleeve 2 and the sleeve 8, and finally ensure the relative stillness of the shaft shoulder and the workpiece.

Specific Embodiment 2: This embodiment is described with reference to FIGS. 1 to 4. The relative position adjustment mechanism of a floating friction stir welding device that realizes self-repair by solid phase addition in this embodiment includes an upper saddle 3, Right support arm assembly 4, connecting rod 5, transmission lead screw 6, left support arm assembly 7 and lower saddle 11; Upper saddle 3 and lower saddle 11 are arranged in sequence from top to bottom, and the right end of upper saddle 3 passes right The support arm assembly 4 is connected with the right end of the lower saddle 11, the left end of the upper saddle 3 is connected with the left end of the lower saddle 11 through the left support arm assembly 7, the left end of the connecting rod 5 is connected with the left support arm assembly 7, and the transmission screw The right end of 6 is connected with the right supporting arm assembly 4, the right end of the connecting rod 5 is connected with the left end of the transmission screw 6 in rotation, the lower surface of the axle sleeve 2 is fixedly connected with the upper surface of the upper saddle 3, and the upper surface of the sleeve 8 is connected with the upper surface of the upper saddle 3. The lower surface of the lower saddle 11 is fixedly connected. The starting point of the driving screw 6 corresponds to the starting point of the height adjustment, and the length is 10-50mm. The right-hand thread can control the up and down movement of the adjustment mechanism according to the rotation direction of the motor shaft. Other components and connections are the same as those in the first embodiment.

Specific Embodiment Three: This embodiment is described with reference to FIGS. 1 to 4. The relative position adjustment mechanism of a floating friction stir welding device for self-repairing by solid-phase additives described in this embodiment also includes a thrust bearing 10, The left end of the transmission screw 6 is rotationally connected with the right end of the connecting rod 5 through a thrust bearing 10 . The starting position of the transmission screw 6 corresponds to the starting and ending positions of the height adjustment, so as to avoid mechanism damage caused by overadjustment, wherein the length of the square hole 502 of the connecting rod 5 corresponds to the starting and ending positions of the main shaft 1 during the height adjustment process.

In this embodiment, the right end of the connecting rod 5 is provided with a square hole 502, and the left end of the transmission screw 6 is inserted into the square hole 502 from right to left. The left end of the lead screw 6, and the thrust bearing 10 is located between the end cover 602 and the inner wall of the square hole 502.

Other components and connections are the same as those in the second embodiment.

Specific Embodiment 4: This embodiment is described with reference to FIGS. 1 to 4. The right support arm assembly 4 of a floating friction stir welding device described in this embodiment includes a right upper support arm 401, a right Lower support arm 402 and leading screw nut 403; The upper end of right upper support arm 401 is connected with the right end of upper saddle 3 in rotation, the lower end of right upper support arm 401 is connected with lead screw nut 403 in rotation, and the upper end of right lower support arm 402 is connected with leading screw Nut 403 is rotatably connected, and the lower end 402 of right lower support arm 402 is rotatably connected with the right end of lower saddle 11, and the right end of driving screw 6 is inserted in the leading screw nut 403.

The thread 601 on the transmission lead screw 6 is threadedly matched with the lead screw nut 403 to realize the drive lead screw 6 to drive the lead screw nut 40 . Other components and connections are the same as those in the second embodiment.

Specific Embodiment 5: This embodiment is described with reference to FIGS. 1 to 4. The left support arm assembly 7 of a floating friction stir welding device described in this embodiment includes a left upper support arm 701, a lower left Support arm 702 and connector 703; the upper end of left upper support arm 701 is rotationally connected with the left end of upper saddle 3, the lower end of left upper support arm 701 is rotationally connected with connector 703, and the upper end of left lower support arm 702 is rotationally connected with connector 703, The lower end of the left lower support arm 702 is rotatably connected with the left end of the lower saddle 11 .

In this embodiment, the left end of the connecting rod 5 is provided with a limiting end cap 501 , and the limiting end cap 501 is located outside the connecting piece 703 to prevent the connecting rod 5 from slipping out of the connecting piece 703 . Other components and connections are the same as those in the second embodiment.

Specific embodiment six: This embodiment is described in conjunction with Fig. 1, Fig. 5 and Fig. 6. The sleeve 8 of a floating friction stir welding device for self-repairing by solid phase addition described in this embodiment includes a first positioning platform 801 and the shaft shoulder 805; the upper end of the shaft shoulder 805 is fixedly connected with the middle part of the lower surface of the first positioning platform 801, and the shaft shoulder 805 is provided with a material storage chamber 803 that runs through the upper and lower surfaces of the shaft shoulder 805, and the first positioning platform There is a through hole in the middle of the upper surface of 801, and the through hole communicates with the material storage chamber 803. The upper surface of the first positioning platform 801 has two positioning holes 802 symmetrically. The outer wall of the upper end of the shoulder 805 is provided with a wire inlet 804. , and the wire inlet 804 communicates with the material storage chamber 803 , and the upper surface of the first positioning platform 801 is fixedly connected with the lower surface of the lower saddle 11 . The number of wire inlets 804 is at least one, and the use of multiple wire inlets 804 can not only realize high-efficiency additive welding but also realize simultaneous additive welding of different materials. The first positioning platform 801 cooperates with the shaft shoulder 805 as a reference plane to realize the airtightness of the broken wire space, thereby avoiding overflow of the broken welding wire. Other compositions and connections are the same as those in Embodiment 1 or 2.

Specific Embodiment 7: This embodiment is described in conjunction with FIG. 1 and FIG. 7. The additive stirring head 9 of a floating friction stir welding device described in this embodiment includes a clamping surface 901, a second Second positioning platform 902, broken wire blade 903, variable pitch thread section 904 and three milling plane stirring needles 905; clamping surface 901, second positioning platform 902, broken wire blade 903, variable pitch thread section 904 and three milling plane stirring needles 905 is sequentially connected into one body from top to bottom, and the clamping surface 901 is fixedly connected with the lower end of the main shaft 1 . The conveying direction of the variable-pitch thread 904 is downward to realize the aggregation and thermoplasticization of additive raw materials, and a right-handed thread that rotates clockwise is adopted. The upper end of the clamping surface 901 is provided with a positioning plane, and the positioning plane is processed according to the clamping requirements of the friction stir welding machine handle.

The three-milling plane stirring needle 905 penetrates into the workpiece to be welded under the state of high-speed rotation and makes the shoulder contact with the surface of the workpiece. The rotation speed is 500rpm-5000rpm; then feeds the filamentary additive material at a speed of additive stirring 1 to 5 times the speed of the head 9; after entering the sleeve 8, the filamentary additive raw material is first interrupted by the broken wire blade 903, and then through the stirring friction and transmission of the variable-pitch thread 904, it reaches thermoplasticity in the storage chamber 803. At the same time, the shaft shoulder is retracted by 0.3-3mm through the relative position adjustment mechanism, and then the additive material stirring head 9 starts to advance for welding; The additive material is evenly formed on the surface of the weld under the pressure of the shoulder.

Other compositions and connections are the same as those in Embodiment 1 or 2.

Embodiment 8: This embodiment is described in conjunction with Fig. 1 and Fig. 7. The three-milling plane stirring needle 905 of a floating friction stir welding device described in this embodiment is a three-milling plane conical shape needle structure. Adopting this design can effectively promote the plastic flow of the material, so that the internal shape of the weld seam is good without defects. Other compositions and connections are the same as those in Embodiment 7.

Ninth specific embodiment: This embodiment is described in conjunction with Fig. 1 to Fig. 7. A floating friction stir welding method in which solid-phase additives realize self-repair described in this embodiment is realized through the following steps:

Step 1. Feed the filamentary additive raw material into the sleeve 8 through the wire inlet 804;

Step 2: The additive raw material is cut off by the broken wire blade 903, and then is stirred and rubbed by the variable-pitch thread 904 to realize continuous downward movement and accumulation;

Step 3, the third milling plane stirring needle 905 rotates at a high speed and plunges into the docking workpiece, so that a closed space is formed between the weld seam and the shaft shoulder;

Step 4: Under the continuous rotation of the additive mixing head 9, the granular additive raw material is gradually transformed into a thermoplastic state under high temperature and high pressure in the closed sleeve 8;

Step 5. While the additive stirring head 9 is advancing along the weld seam, the gap between the thermoplastic additive raw material shoulder and the weld seam is additively formed to realize the repair of thinning, an inherent defect of friction stir welding, and to improve the butt joint. gap tolerance;

Step 6. At the end of welding, when the main shaft 1 drives the additive stirring head 9 to move up, the relative position adjustment mechanism between the shaft sleeve 2 and the sleeve 8 starts to operate, and the motor drives the transmission screw 6 to rotate, and then drives the The right support arm assembly 4 and the left support arm assembly 7 are opened, and finally the relative movement between the sleeve 8 and the additive mixing head 9 is realized, that is, the shaft shoulder and the workpiece remain relatively stationary;

Step 7. When the lower plane of the three-milling plane stirring pin 905 reaches the level of the shaft shoulder, the relative position adjustment mechanism stops running and moves up together with the main shaft 1, and the self-repairing welding process ends.

The material of the filamentary additive material in this embodiment includes, but is not limited to, aluminum, aluminum alloy, magnesium alloy and other light alloys with low melting points.

In this embodiment, the plane of the root of the three-milling plane stirring needle 905 is coplanar with the bottom of the shoulder. During the welding process, the control of the thinning of the weld can be realized. At the same time, the thickening and increase of the weld can be further realized by adjusting the position of the shoulder. Width.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, may use the technical content disclosed above to make some changes or modify equivalent embodiments with equivalent changes, but as long as they do not depart from the technical solution of the present invention, according to the technical content of the present invention Within the spirit and principles of the present invention, any simple modifications, equivalent replacements and improvements made to the above embodiments still fall within the scope of protection of the technical solutions of the present invention.

Claims (8)

1. A solid phase material-adding realizes self-repairing floating friction stir welding device which is characterized in that: the floating friction stir welding device for realizing self-repairing of solid-phase material addition comprises a main shaft (1), a shaft sleeve (2), a relative position adjusting mechanism, a sleeve (8) and an material addition stirring head (9); the shaft sleeve (2) is arranged on the upper surface of the relative position adjusting mechanism, the sleeve (8) is arranged on the lower surface of the relative position adjusting mechanism, the upper part of the material adding stirring head (9) is inserted into the lower end of the sleeve (8) from bottom to top, the lower part of the main shaft (1) is inserted into the upper end of the shaft sleeve (2) from top to bottom, and the lower end of the main shaft (1) is fixedly connected with the upper end of the material adding stirring head (9); the relative position adjusting mechanism comprises an upper saddle (3), a right supporting arm assembly (4), a connecting rod (5), a transmission screw (6), a left supporting arm assembly (7) and a lower saddle (11); the upper saddle (3) and the lower saddle (11) are sequentially arranged from top to bottom, the right end of the upper saddle (3) is connected with the right end of the lower saddle (11) through a right supporting arm assembly (4), the left end of the upper saddle (3) is connected with the left end of the lower saddle (11) through a left supporting arm assembly (7), the left end of the connecting rod (5) is connected with the left supporting arm assembly (7), the right end of the transmission screw (6) is connected with the right supporting arm assembly (4), the right end of the connecting rod (5) is rotationally connected with the left end of the transmission screw (6), the lower surface of the shaft sleeve (2) is fixedly connected with the upper surface of the upper saddle (3), and the upper surface of the sleeve (8) is fixedly connected with the lower surface of the lower saddle (11).

2. The floating friction stir welding device for achieving self-repairing by solid phase additive according to claim 1, wherein the floating friction stir welding device is characterized in that: the relative position adjusting mechanism further comprises a thrust bearing (10), and the left end of the transmission screw rod (6) is rotationally connected with the right end of the connecting rod (5) through the thrust bearing (10).

3. The floating friction stir welding device for achieving self-repairing by solid phase additive according to claim 1, wherein the floating friction stir welding device is characterized in that: the right support arm assembly (4) comprises a right upper support arm (401), a right lower support arm (402) and a screw nut (403); the upper end of the right upper supporting arm (401) is rotationally connected with the right end of the upper saddle (3), the lower end of the right upper supporting arm (401) is rotationally connected with the screw nut (403), the upper end of the right lower supporting arm (402) is rotationally connected with the screw nut (403), the lower end of the right lower supporting arm (402) is rotationally connected with the right end of the lower saddle (11), and the right end of the transmission screw (6) is inserted in the screw nut (403).

4. The floating friction stir welding device for achieving self-repairing by solid phase additive according to claim 1, wherein the floating friction stir welding device is characterized in that: the left support arm assembly (7) comprises a left upper support arm (701), a left lower support arm (702) and a connecting piece (703); the upper end of the left upper supporting arm (701) is rotationally connected with the left end of the upper saddle (3), the lower end of the left upper supporting arm (701) is rotationally connected with the connecting piece (703), the upper end of the left lower supporting arm (702) is rotationally connected with the connecting piece (703), and the lower end of the left lower supporting arm (702) is rotationally connected with the left end of the lower saddle (11).

5. The floating friction stir welding device for achieving self-repairing by solid phase additive according to claim 1, wherein the floating friction stir welding device is characterized in that: the sleeve (8) comprises a first positioning platform (801) and a shaft shoulder (805); the upper end of shaft shoulder (805) and the middle part fixed connection of first location platform (801) lower surface become integrative, are equipped with in shaft shoulder (805) and run through storage chamber (803) of shaft shoulder (805) up end and lower terminal surface, and open at the middle part of first location platform (801) upper surface has the through-hole, the through-hole communicates with storage chamber (803), and open the upper surface symmetry of first location platform (801) has two locating holes (802), and the lateral wall of shaft shoulder (805) upper end is equipped with into silk mouth (804), and advances silk mouth (804) and storage chamber (803) intercommunication, the upper surface of first location platform (801) and the lower fixed surface of saddle (11) down are connected.

6. The floating friction stir welding device for achieving self-repairing by solid phase additive according to claim 1, wherein the floating friction stir welding device is characterized in that: the material adding stirring head (9) comprises a clamping surface (901), a second positioning platform (902), a wire breaking blade (903), a variable-pitch thread section (904) and a three-milling-plane stirring pin (905); the clamping surface (901), the second positioning platform (902), the wire breaking blade (903), the variable-pitch thread section (904) and the three-milling-plane stirring needle (905) are sequentially connected into a whole from top to bottom, and the clamping surface (901) is fixedly connected with the lower end of the main shaft (1).

7. The solid phase additive self-repairing floating friction stir welding device according to claim 6, wherein: the three-milling-plane stirring pin (905) is a three-milling-plane conical pin structure.

8. A floating friction stir welding method for realizing self-repairing by solid phase material addition is characterized in that: a floating friction stir welding device for realizing self-repairing of solid-phase material addition comprises a main shaft (1), a shaft sleeve (2), a relative position adjusting mechanism, a sleeve (8) and an material addition stirring head (9); the shaft sleeve (2) is arranged on the upper surface of the relative position adjusting mechanism, the sleeve (8) is arranged on the lower surface of the relative position adjusting mechanism, the upper part of the material adding stirring head (9) is inserted into the lower end of the sleeve (8) from bottom to top, the lower part of the main shaft (1) is inserted into the upper end of the shaft sleeve (2) from top to bottom, and the lower end of the main shaft (1) is fixedly connected with the upper end of the material adding stirring head (9); the relative position adjusting mechanism comprises an upper saddle (3), a right supporting arm assembly (4), a connecting rod (5), a transmission screw (6), a left supporting arm assembly (7) and a lower saddle (11); the upper saddle (3) and the lower saddle (11) are sequentially arranged from top to bottom, the right end of the upper saddle (3) is connected with the right end of the lower saddle (11) through a right supporting arm assembly (4), the left end of the upper saddle (3) is connected with the left end of the lower saddle (11) through a left supporting arm assembly (7), the left end of the connecting rod (5) is connected with the left supporting arm assembly (7), the right end of the transmission screw (6) is connected with the right supporting arm assembly (4), the right end of the connecting rod (5) is rotationally connected with the left end of the transmission screw (6), the lower surface of the shaft sleeve (2) is fixedly connected with the upper surface of the upper saddle (3), and the upper surface of the sleeve (8) is fixedly connected with the lower surface of the lower saddle (11);

the relative position adjusting mechanism further comprises a thrust bearing (10), and the left end of the transmission screw rod (6) is rotationally connected with the right end of the connecting rod (5) through the thrust bearing (10);

the right support arm assembly (4) comprises a right upper support arm (401), a right lower support arm (402) and a screw nut (403); the upper end of the right upper supporting arm (401) is rotationally connected with the right end of the upper saddle (3), the lower end of the right upper supporting arm (401) is rotationally connected with the screw nut (403), the upper end of the right lower supporting arm (402) is rotationally connected with the screw nut (403), the lower end of the right lower supporting arm (402) is rotationally connected with the right end of the lower saddle (11), and the right end of the transmission screw (6) is inserted in the screw nut (403);

the left support arm assembly (7) comprises a left upper support arm (701), a left lower support arm (702) and a connecting piece (703); the upper end of the left upper supporting arm (701) is rotationally connected with the left end of the upper saddle (3), the lower end of the left upper supporting arm (701) is rotationally connected with the connecting piece (703), the upper end of the left lower supporting arm (702) is rotationally connected with the connecting piece (703), and the lower end of the left lower supporting arm (702) is rotationally connected with the left end of the lower saddle (11);

the sleeve (8) comprises a first positioning platform (801) and a shaft shoulder (805); the upper end of the shaft shoulder (805) is fixedly connected with the middle part of the lower surface of the first positioning platform (801) into a whole, a material storage cavity (803) penetrating through the upper end face and the lower end face of the shaft shoulder (805) is arranged in the shaft shoulder (805), a through hole is formed in the middle part of the upper surface of the first positioning platform (801), the through hole is communicated with the material storage cavity (803), two positioning holes (802) are symmetrically formed in the upper surface of the first positioning platform (801), a wire inlet (804) is formed in the outer side wall of the upper end of the shaft shoulder (805), the wire inlet (804) is communicated with the material storage cavity (803), and the upper surface of the first positioning platform (801) is fixedly connected with the lower surface of the lower saddle (11);

the material adding stirring head (9) comprises a clamping surface (901), a second positioning platform (902), a wire breaking blade (903), a variable-pitch thread section (904) and a three-milling-plane stirring pin (905); the clamping surface (901), the second positioning platform (902), the wire breaking blade (903), the variable-pitch thread section (904) and the three-milling-plane stirring pin (905) are sequentially connected into a whole from top to bottom, and the clamping surface (901) is fixedly connected with the lower end of the main shaft (1);

the three-milling-plane stirring pin (905) is of a three-milling-plane conical pin structure;

the floating friction stir welding method for realizing self-repairing by solid phase material addition is realized by the following steps:

step one, feeding a silk-like additive raw material into a sleeve (8) through a silk inlet (804);

step two, cutting off the material adding raw materials by a wire cutting blade (903), and then stirring, rubbing and conveying the material adding raw materials by a variable-pitch thread section (904) to realize continuous downward movement accumulation;

thirdly, a three-milling plane stirring pin (905) is rotated at a high speed and is pricked into a butt joint workpiece, so that a closed space is formed between a welding line and a shaft shoulder;

step four, under the continuous rotation of the material adding stirring head (9), the granular material adding raw materials are gradually transformed into a thermoplastic state under high temperature and high pressure in the airtight sleeve (8);

step five, performing additive forming on a gap between a thermoplastic additive raw material shaft shoulder and a welding line while an additive stirring head (9) advances along the welding line, so as to repair the inherent defect of thinning friction stir welding and improve the gap tolerance of a butt joint;

step six, when welding is finished, in the process that the main shaft (1) drives the additive stirring head (9) to move upwards, a relative position adjusting mechanism between the shaft sleeve (2) and the sleeve (8) starts to operate, the motor drives the transmission screw rod (6) to rotate, and then drives the right supporting arm assembly (4) and the left supporting arm assembly (7) to open, so that the relative movement of the sleeve (8) and the additive stirring head (9) is finally realized, namely, the shaft shoulder and the workpiece keep relatively static;

and seventhly, stopping the operation of the relative position adjusting mechanism when the lower plane of the three-milling plane stirring pin (905) reaches the horizontal position of the shaft shoulder, and moving upwards together with the main shaft (1) to finish the self-repairing welding process.

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