Welding tool and wide and narrow slit self-adaptive welding method
By adjusting the eccentric rotation amplitude of the welding wire in real time, the problem of incomplete coverage of the narrow gap GMAW welding device on welds of different widths is solved, and the welding quality and efficiency are improved.
Patent Information
- Application Number
- CN202510379185.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-28
- Publication Date
- 2025-08-15
AI Technical Summary
The existing narrow gap GMAW welding device is difficult to adaptively adjust the eccentric distance of the welding wire, resulting in incomplete wire coverage and uneven welding quality.
Welding tools with a distance adjustment mechanism are used to monitor the changes in the weld width in real time, adjust the position of the rotating body in the shell, change the eccentric rotation amplitude of the end of the welding wire to ensure the appropriate arc length.
The uniform coverage of welding wire on the weld is achieved, the welding quality is improved, and the welding effect of welds of different widths is adapted to the problem of inconsistent welding quality.
Smart Images
Figure CN120480352A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of welding guns, in particular to a welding tool and a wide-narrow seam adaptive welding method. Background Art
[0002] Narrow Gap Gas Metal Arc Welding (GMAW) is an advanced welding technology primarily used for joining thick plate materials. Its advantages include moderate heat input, high welding efficiency, suitability for all-position welding, and excellent overall performance. This technology is particularly well-suited for applications requiring reduced weld distortion, increased productivity, and improved weld quality.
[0003] The main technical difficulties of narrow-gap GMAW welding are sidewall incompatibility and weld spatter. The groove gap size is usually 9 to 12 mm. The fundamental solution to sidewall incompatibility is to keep the arc burning close to the sidewall, thereby increasing the heat input to the sidewall.
[0004] The narrow-gap GMAW welding technique currently employed employs an eccentric rotation method. In this method, the welding wire is fed into the center of the welding gun's conductive rod and ejected eccentrically via an eccentric hole at the end of the contact tip connected to the rod. The rod and tip rotate, causing the welding wire exiting the tip to rotate eccentrically around the rod's central axis.
[0005] During actual welding, the groove gap size along the weld seam varies, and the distance between the end of the welding wire and the sidewall directly affects the arc length, which in turn affects the welding quality. While existing welding devices typically rely on a fixed design to adjust the eccentricity of the welding wire, it is difficult to adaptively adjust the eccentricity of the welding wire during welding to accommodate welds of varying widths. Existing welding devices present problems during welding, such as incomplete wire coverage and uneven weld quality. Therefore, a welding device capable of real-time adjustment of the yaw amplitude of the eccentric motion of the welding wire is urgently needed. Summary of the Invention
[0006] The embodiments of the present invention provide a welding tool and a wide-narrow seam adaptive welding method to solve the problems in the prior art.
[0007] The embodiment of the present invention adopts the following technical solution: a welding tool, comprising: a shell; a rotating body, having a connecting part and a rotating part connected to each other, and the central axes of the connecting part and the rotating part are eccentrically arranged; the connecting part is driven to rotate by power to force the rotating part to rotate eccentrically; a conductive rod, movably arranged on an elastic support member in the shell, and the end of the conductive rod is connected to a conductive nozzle, and the conductive nozzle is located at the open end of the shell; a connecting member, arranged between the rotating body and the conductive rod, one end of the connecting member is connected to the rotating part through an automatic centering connection structure, and the other end of the connecting member is slidably matched with the conductive rod, so that when the rotating part rotates eccentrically, the conductive rod swings with the elastic support member as a fulcrum; a distance adjustment mechanism, whose executive end is movably connected to the rotating body, and drives the rotating body to move in the shell to realize relative sliding between the connecting member and the conductive rod; the rotating body, the connecting member, the conductive rod and the conductive nozzle are all provided with holes to form a channel for the welding wire to pass through.
[0008] Preferably, the distance adjustment mechanism includes: a connecting plate, whose end face is provided with a through hole; a first bearing member, fixedly assembled in the through hole, and the central axis of the connecting part is coaxially mounted on the first bearing member; a linear drive source, whose output shaft is connected to the connecting plate to drive the connecting plate to move axially along the central axis.
[0009] Preferably, a hollow shaft motor is further installed in the housing, the output shaft of the hollow shaft motor is coaxially connected to the central shaft to drive the central shaft to rotate, and the output shaft of the hollow shaft motor is connected to the channel.
[0010] Preferably, the outer wall of the center shaft is configured as a spline structure, and the inner wall of the output shaft of the hollow shaft motor is set as a spline groove; the center shaft is slidably inserted into the spline groove to achieve circumferential limitation of the center shaft relative to the output shaft of the hollow shaft motor.
[0011] Preferably, the automatic self-aligning connection structure is configured as a self-aligning ball bearing mounted on the rotating body, and one end of the connecting member is coaxially mounted on the self-aligning ball bearing.
[0012] Preferably, the connecting piece is configured as a tubular structure, and the connecting piece is slidably inserted into the top sliding groove of the conductive rod.
[0013] Preferably, a flexible disk is provided at the elastic support member, which includes an outer ring and an inner ring. The outer ring is connected to the inner wall of the shell, and the inner ring is connected to the outer ring through a plurality of elastically deformable connecting arms. The conductive rod at least partially passes through the inner ring and the limiting wall on the conductive rod abuts against the upper end of the inner ring.
[0014] A wide-narrow seam adaptive welding method comprises the following steps: S1: The welding wire moves through the channel inside the welding tool and exits, and an electric arc is generated through the open end of the welding tool housing so that the welding wire is welded to the weld to be processed, and the welding tool is moved along the direction of the weld by the robotic arm device; S2: The rotating body inside the housing is eccentrically rotated by power drive, so as to drive the conductive rod to swing with the elastic support inside the housing as a fulcrum, and the end of the welding wire follows the circular or elliptical trajectory of the conductive nozzle and the conductive rod to rotate eccentrically, so that the molten welding wire covers the weld; S3: According to the change of the real-time monitored arc length, the distance adjustment mechanism inside the housing controls the movement of the rotating body inside the housing to change the distance L between the rotating body and the swing mounting point, and increase or decrease the eccentric rotation amplitude of the end of the welding wire.
[0015] Preferably, in step S3, it further includes: Set the standard arc length G0, and the real-time arc length is G 1， By monitoring the real-time welding voltage V1 and monitoring the real-time arc length G1, when the real-time arc length is G1 = G0, the welding voltage is the standard welding voltage V0; When it is monitored that the real-time welding voltage V1 > V0, it is determined that the real-time arc length is G1 > G0, and the distance adjustment mechanism inside the housing controls the rotating body to rise inside the housing, so that the distance L between the rotating body and the swing mounting point increases, and the eccentric rotation amplitude of the end of the welding wire is reduced until the real-time welding voltage V1 = V0; When it is monitored that the real-time welding voltage V1 < V0, it is determined that the real-time arc length is G1 < G0, and the distance adjustment mechanism inside the housing controls the rotating body to descend inside the housing, so that the distance L between the rotating body and the swing mounting point is reduced, and the eccentric rotation amplitude of the end of the welding wire is increased until the real-time welding voltage V1 = V0.
[0016] The above at least one technical solution adopted in the embodiment of the present invention can achieve the following beneficial effects: This welding tool has a distance adjustment mechanism, which can control the movement of the rotating body inside the housing according to the change of the weld width monitored in real time, and then change the distance between the rotating body and the swing mounting point, so as to increase or decrease the eccentric rotation amplitude of the end of the welding wire. This function of adjusting the swing amplitude in real time enables it to flexibly adapt to welds of different widths, ensuring that during the welding process, the arc length between the welding wire and the side wall of the weld is maintained appropriately, ensuring that the welding heat input can adapt to the change of the weld width, greatly improving the welding effect, and effectively avoiding problems such as incomplete coverage of the welding wire and uneven welding quality caused by different weld widths. Description of the Drawings
[0017] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention; Figure 2 It is a sectional view of the three-dimensional structure of the present invention; Figure 3 It is a schematic structural diagram of the interior of the housing of the present invention; Figure 4 Schematic diagram of the distance adjustment mechanism of the present invention; Figure 5 An exploded view of the hollow shaft motor and the rotating body of the present invention; Figure 6 is a cross-sectional view of the rotating body of the present invention; Figure 7 This is an exploded view of the flexible disk and the conductive rod of the present invention.
[0018] Reference numerals:
[0019] 1-housing; 11-hollow shaft motor; 111-spline groove; 12-flexible disk; 121-outer ring; 122-inner ring; 123-connecting arm; 2-rotating body; 21-center axis; 22-automatic centering connection structure; 3-conductive rod; 31-conductive nozzle; 32-slide; 33-limiting wall; 4-connecting part; 5-distance adjustment mechanism; 51-connecting plate; 511-perforation; 52-first bearing part; 53-linear drive source; 6-channel. DETAILED DESCRIPTION
[0020] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.
[0021] The technical solutions provided by various embodiments of the present invention are described in detail below with reference to the accompanying drawings.
[0022] Reference Figures 1 to 7 As shown, an embodiment of the present invention provides a welding tool, which mainly includes a shell 1, a rotating body 2, a conductive rod 3, a connecting piece 4 and a distance adjustment mechanism 5. Holes are provided on the rotating body 2, the connecting piece 4, the conductive rod 3 and the conductive nozzle 31 to form a channel 6 for the welding wire to pass through.
[0023] The rotating body 2 has a connecting portion and a rotating portion connected to each other (the connecting portion is Figure 6 The upper part of the structure connected to the central axis is the rotating part Figure 6The lower half structure connected to the connecting member 4 in the middle), and the central axis of the connecting portion and the rotating portion is eccentrically arranged; the connecting portion is driven to rotate by power to force the rotating portion to rotate eccentrically; and the rotating body 2 has an automatic centering connection structure 22 arranged coaxially therewith. In some practical applications, a hollow shaft motor 11 is also installed in the housing 1, and the output shaft of the hollow shaft motor 11 is coaxially connected to the central shaft 21 to drive the central shaft 21 to rotate, and the output shaft of the hollow shaft motor 11 is connected to the channel 6. In some practical applications, the automatic centering connection structure 22 is configured as a self-aligning ball bearing mounted on the rotating body 2, and one end of the connecting member 4 is coaxially mounted on the self-aligning ball bearing.
[0024] Because the rotating body 2 has a central axis 21 that allows for eccentric rotation, and the conductive rod 3 swings around the elastic support within the housing 1, the conductive tip 31, the conductive rod 3, and the end of the welding wire can simultaneously rotate eccentrically along a circular or elliptical trajectory. This design allows the welding wire to be fed not in a simple linear motion, but rather through a regular oscillation, allowing the welding solution to be more comprehensively and evenly distributed across the weld seam. This further improves the coverage of the welding wire across the weld seam compared to conventional welding tools that only feed the wire in a straight line.
[0025] The conductive rod 3 is movably arranged at the elastic support member inside the housing 1, and the end of the conductive rod 3 is connected to a conductive nozzle 31, which is located at the open end of the housing 1. The conductive rod 3 and the conductive nozzle 31 are conventional. The conductive rod 3 is an important component for current transmission. One end of the conductive rod 3 is usually in contact with the power connection line inside the welding gun, and can receive the current output from the welding power supply, and then conduct the current along itself to the other end, which is the part connected to the conductive nozzle 31. The conductive nozzle 31 is at the end of the current transmission path. It is connected to the conductive rod 3, receives the current conducted from the conductive rod 3, and transmits the current to the welding wire. During the welding process, the welding wire passes through the conductive nozzle 31. When the current is transmitted to the welding wire through the conductive nozzle 31, a loop is formed between the welding wire and the workpiece, and a high-temperature arc is generated at the end of the welding wire. This is a key link in achieving welding, ensuring that the electrical energy required for welding can accurately act on the welding wire, causing the welding wire to melt.
[0026] The connector 4 is disposed between the rotating body 2 and the conductive rod 3. One end of the connector 4 is mounted on the self-aligning connection structure 22, and the other end of the connector 4 slides with the conductive rod 3. This allows the conductive rod 3 to swing about the elastic support member when the rotating body 2 rotates eccentrically. Specifically, the connector 4 is configured as a tubular structure and slides into the top slot 32 of the conductive rod 3, achieving a sliding fit between the connector 4 and the conductive rod 3.
[0027] The distance adjustment mechanism 5 has an execution end movably connected to the rotating body 2 , thereby driving the rotating body 2 to move in the housing 1 to achieve relative sliding between the connecting member 4 and the conductive rod 3 .
[0028] In this embodiment, the welding tool features a distance adjustment mechanism 5 that controls the movement of the rotating body 2 within the housing 1 based on real-time monitoring of weld seam width changes. This mechanism, in turn, changes the distance between the rotating body 2 and the swing mounting point, thereby increasing or decreasing the eccentric rotation amplitude of the welding wire end. This real-time adjustment of the swing amplitude allows for flexible adaptation to welds of varying widths, ensuring that the arc length between the welding wire and the weld seam sidewall remains appropriate during welding, ensuring that the welding heat input can adapt to varying weld seam widths. This effectively avoids problems such as incomplete wire coverage and uneven welding quality caused by varying weld seam widths.
[0029] In some practical applications, refer to Figures 2 to 4 As shown, the distance adjustment mechanism 5 includes a connecting plate 51 , a first bearing member 52 and a linear drive source 53 .
[0030] The connecting plate 51 has a through-hole 511 on its end surface. A first bearing 52 is fixedly mounted within this through-hole 511, and the central shaft 21 is coaxially mounted on the first bearing 52. The output shaft of a linear drive source 53 is connected to the connecting plate 51 to drive the connecting plate 51 to move axially along the central shaft 21. During operation, the linear drive source 53 serves as the source of power, and the linear motion of its output shaft drives the connecting plate 51 to move axially along the central shaft 21. This movement of the connecting plate 51 synchronously drives the first bearing 52, which is fixedly mounted within its through-hole 511. Since the central shaft 21 is coaxially mounted on the first bearing 52, the rotating body 2 (of which the central shaft 21 is a part) also undergoes corresponding axial displacement within the housing 1. The distance adjustment mechanism 5 precisely adjusts the position of the rotating body 2 according to changes in the weld seam width, effectively changing the eccentric rotation amplitude of the welding wire in real time.
[0031] Based on any of the above embodiments, refer to Figure 5 As shown, the outer wall of the center shaft 21 is configured as a spline structure, and the inner wall of the output shaft of the hollow shaft motor 11 is set as a spline groove 111; the center shaft 21 is slidably inserted into the spline groove 111 to achieve circumferential limitation of the center shaft 21 relative to the output shaft of the hollow shaft motor 11. Therefore, the hollow shaft motor 11 can not only realize the rotation of the rotating body 2, but also give the center shaft 21 a certain axial activity space when the pitch adjustment component is driven.
[0032] In other practical applications, refer to Figure 2 and Figure 7As shown, a flexible disk 12 is disposed on the elastic support member. The flexible disk 12 includes an outer ring 121 and an inner ring 122. The outer ring 121 is connected to the inner wall of the housing 1, and the inner ring 122 is connected to the outer ring 121 via a plurality of elastically deformable connecting arms 123. The conductive rod 3 at least partially passes through the inner ring 122, and the limiting wall 33 on the conductive rod 3 abuts the upper end of the inner ring 122. When the welding tool is in operation, as the rotating body 2 rotates eccentrically and drives the conductive rod 3 to swing through the connecting member 4, the conductive rod 3 swings regularly with the elastic support member (i.e., the location of the flexible disk 12) as the fulcrum. The flexible disk 12, with its unique structure of the outer ring 121, inner ring 122, and connecting arms 123, can ensure the swinging flexibility of the conductive rod 3 while effectively buffering the impact force during the swinging process, absorbing vibration energy, and maintaining the stability of the entire structure.
[0033] A wide-narrow seam adaptive welding method comprises the following steps: S1: The welding wire moves through the channel 6 inside the welding tool and passes through the open end of the welding tool housing 1 to generate an arc so that the welding wire is welded to the weld to be processed. The welding tool is then moved along the direction of the weld by a robotic arm device (specifically, an industrial robotic arm can clamp the welding tool and drive it to move along the direction of the weld); S2: The rotating body 2 inside the housing 1 is driven by power to rotate eccentrically, thereby driving the conductive rod 3 to swing with the elastic support member inside the housing 1 as a fulcrum. The end of the welding wire rotates eccentrically in a circular or elliptical trajectory following the conductive tip 31 and the conductive rod 3, so that the molten welding wire covers the entire weld seam. S1: The welding wire moves through the channel 6 inside the welding tool and passes through the open end of the welding tool housing 1 to generate an arc so that the welding wire is welded to the weld to be processed, and the welding tool is moved along the direction of the weld by the robotic arm device; S2: The rotating body 2 inside the housing 1 is driven by power to rotate eccentrically, thereby driving the conductive rod 3 to swing with the elastic support member inside the housing 1 as a fulcrum. The end of the welding wire rotates eccentrically in a circular or elliptical trajectory following the conductive tip 31 and the conductive rod 3, so that the molten welding wire covers the entire weld seam. S3: Based on the real-time monitoring of the change in arc length, the distance adjustment mechanism 5 inside the shell 1 controls the movement of the rotating body 2 inside the shell 1 to change the distance L between the rotating body 2 and the swing mounting point, thereby increasing or decreasing the eccentric rotation amplitude of the end of the welding wire.
[0034] Specifically, in step S3, it further includes: Set the standard arc length G0, the real-time arc length is G 1， By monitoring the real-time welding voltage V1 and the real-time arc length G1, when the real-time arc length is G1=G0, the welding voltage is the standard welding voltage V0; When it is monitored that the real-time welding voltage V1 > V0, it is determined that the real-time arc length is G1 > G0. The distance adjustment mechanism 5 inside the housing 1 controls the rotating body 2 to rise inside the housing 1, increasing the distance L between the rotating body 2 and the swing mounting point, reducing the eccentric rotation amplitude of the wire end until the real-time welding voltage V1 = V0; When it is monitored that the real-time welding voltage V1 < V0, it is determined that the real-time arc length is G1 < G0. The distance adjustment mechanism 5 inside the housing 1 controls the rotating body 2 to descend inside the housing 1, reducing the distance L between the rotating body 2 and the swing mounting point, increasing the eccentric rotation amplitude of the wire end until the real-time welding voltage V1 = V0.
[0035] Specifically, the implementation principle in step S3 is as follows: During the welding process, there is an approximately proportional relationship between the arc length and the welding voltage. The longer the arc, the higher the welding voltage; the shorter the arc, the lower the welding voltage. Because the arc is essentially a gas discharge phenomenon, an increase in the arc length will cause an increase in the arc resistance. According to Ohm's law, when the welding current is relatively stable, an increase in resistance will cause the voltage to rise. It can be assumed that there is a proportionality coefficient k between the two, such that the welding voltage V and the arc length G satisfy the relationship V = kG. For the standard state, there is V0 = kG0; for the real-time state, then V1 = kG1.
[0036] The above is only a preferred embodiment of the present invention and does not impose any form of limitation on the present invention. Although the present invention has been disclosed as above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.
Claims
1. A welding tool, characterized in that: include: Housing (1); The rotating body (2) has a connecting portion and a rotating portion connected to each other, and the central axes of the connecting portion and the rotating portion are eccentrically arranged; the connecting portion is driven to rotate by power to force the rotating portion to rotate eccentrically; A conductive rod (3) is movably arranged on the elastic support member in the housing (1), and the end of the conductive rod (3) is connected to a conductive nozzle (31), and the conductive nozzle (31) is located at the open end of the housing (1); A connecting member (4) is provided between the rotating body (2) and the conductive rod (3), one end of the connecting member (4) being connected to the rotating part via an automatic centering connection structure (22), and the other end of the connecting member (4) being in sliding engagement with the conductive rod (3), so that when the rotating part rotates eccentrically, the conductive rod (3) swings with the elastic support member as a fulcrum; A distance adjustment mechanism (5), the actuator end of which is movably connected to the rotating body (2), drives the rotating body (2) to move within the housing (1) to achieve relative sliding between the connecting member (4) and the conductive rod (3); The rotating body (2), the connecting piece (4), the conductive rod (3) and the conductive nozzle (31) are all provided with holes to form a channel (6) for the welding wire to pass through.
2. A welding tool according to claim 1, characterized in that: The distance adjustment mechanism (5) comprises: A connecting plate (51) having an end surface provided with a through hole (511); The first bearing member (52) is fixedly assembled in the through hole (511), and the central axis (21) of the connecting portion is coaxially mounted on the first bearing member (52): A linear drive source (53) has an output shaft connected to the connecting plate (51) to drive the connecting plate (51) to move axially along the central axis (21).
3. A welding tool according to claim 1, characterized in that: A hollow shaft motor (11) is also installed in the housing (1), and the output shaft of the hollow shaft motor (11) is coaxially connected to the central shaft (21) of the connecting portion to drive the central shaft (21) to rotate, and the output shaft of the hollow shaft motor (11) is connected to the channel (6).
4. A welding tool according to claim 3, characterized in that: The outer wall of the central shaft (21) is configured as a spline structure, and the inner wall of the output shaft of the hollow shaft motor (11) is provided as a spline groove (111); the central shaft (21) is slidably inserted into the spline groove (111) to achieve circumferential limitation of the central shaft (21) relative to the output shaft of the hollow shaft motor (11).
5. A welding tool according to claim 1, characterized in that: The automatic self-aligning connection structure (22) is configured as a self-aligning ball bearing mounted on the rotating body (2), and one end of the connecting member (4) is coaxially mounted on the self-aligning ball bearing.
6. A welding tool according to claim 1, characterized in that: The connecting piece (4) is configured as a tubular structure, and the connecting piece (4) is slidably inserted into the top sliding groove (32) of the conductive rod (3).
7. A welding tool according to claim 1, characterized in that: The elastic support member is configured as a flexible disk (12), which includes an outer ring (121) and an inner ring (122), wherein the outer ring (121) is connected to the inner wall of the shell (1), and the inner ring (122) is connected to the outer ring (121) via a plurality of elastically deformable connecting arms (123), and the conductive rod (3) at least partially passes through the inner ring (122), and the limiting wall (33) on the conductive rod (3) abuts against the upper end of the inner ring (122).
8. A method for adaptive welding of wide and narrow seams, characterized in that: The following steps are involved: S1: The welding wire moves through the channel (6) inside the welding tool and exits, and an electric arc is generated through the open end of the welding tool housing (1) so that the welding wire is welded to the weld to be processed, and the welding tool is moved along the direction of the weld by the robotic arm device; S2: The rotating body (2) inside the housing (1) is eccentrically rotated by power drive, so as to drive the conducting rod (3) to swing with the elastic support inside the housing (1) as a fulcrum, and the end of the welding wire follows the conducting nozzle (31) and the conducting rod (3) to eccentrically rotate in a circular or elliptical trajectory, so that the welding wire melt covers the weld; S3: According to the change of the real-time monitored arc length, the distance adjusting mechanism (5) inside the housing (1) controls the rotating body (2) to move inside the housing (1), so as to change the distance L between the rotating body (2) and the swing mounting point, and increase or decrease the eccentric rotation amplitude of the end of the welding wire.
9. The method for adaptively welding a wide and narrow seam according to claim 8, characterized in that: In step S3, it further includes: Set the standard arc length G0, the real-time arc length is G1, monitor the real-time welding voltage V1, monitor the real-time arc length G1, when the real-time arc length is G1 = G0, the welding voltage is the standard welding voltage V0; When it is monitored that the real-time welding voltage V1 > V0, it is determined that the real-time arc length is G1 > G0, and the distance adjusting mechanism (5) inside the housing (1) controls the rotating body (2) to rise inside the housing (1), so as to increase the distance L between the rotating body (2) and the swing mounting point, and reduce the eccentric rotation amplitude of the end of the welding wire until the real-time welding voltage V1 = V0; When it is monitored that the real-time welding voltage V1 < V0, it is determined that the real-time arc length is G1 < G0, and the distance adjusting mechanism (5) inside the housing (1) controls the rotating body (2) to descend inside the housing (1), so as to reduce the distance L between the rotating body (2) and the swing mounting point, and increase the eccentric rotation amplitude of the end of the welding wire until the real-time welding voltage V1 = V0.