CN111408825B

CN111408825B - Thick-section narrow-gap T-shaped welding method

Info

Publication number: CN111408825B
Application number: CN202010384516.6A
Authority: CN
Inventors: 金宝; 钟磊; 郭中才; 范潇; 姚文选; 付永贵; 王平; 林松; 彭谢宜
Original assignee: Dongfang Electric Machinery Co Ltd DEC
Current assignee: Dongfang Electric Machinery Co Ltd DEC
Priority date: 2020-05-09
Filing date: 2020-05-09
Publication date: 2021-06-18
Anticipated expiration: 2040-05-09
Also published as: CN111408825A

Abstract

The invention discloses a thick-section narrow-gap T-shaped welding method, and relates to the technical field of production and manufacturing of welding of thick plates and ultra-thick plates in the hydropower industry. According to the invention, the butt joint groove between the special-shaped structure thick plate and the plane thick plate is changed, namely a rectangular structure is processed within a range of 60mm above the welding end of the special-shaped thick plate, the arc welding bead is changed into a linear welding bead, the welding track of a robot can be simplified, the programming difficulty is reduced, an oblique welding surface with a certain inclination is arranged on the welding surface of the rectangular structure, the welding groove between the special-shaped thick plate and the plane thick plate is designed into an I-shaped narrow gap groove structure, the original multi-layer multi-pass welding is changed into one layer, the welding process is simplified, the probability of incomplete fusion between the welding beads and the times of cleaning the welding bead are reduced, and the welding.

Description

Thick-section narrow-gap T-shaped welding method

Technical Field

The invention relates to the technical field of production and manufacturing of welding of thick plates and ultra-thick plates in the hydropower industry, in particular to a T-shaped welding method with thick section and narrow gap.

Background

The thick plate and ultra-thick plate structure is widely applied to the hydropower manufacturing industry, the thick plate welding joint mainly comprises butt joint, T joint and the like, and the traditional welding method of the T joint generally adopts a workpiece K-shaped groove to carry out multilayer multi-path MAG welding. Along with the continuous increase of welding structure thickness, thick plate groove area sharply increases, leads to welding engineering volume to multiply, and production efficiency is low, and during multilayer multichannel welding, easily lead to fusing badly.

Because the stability of welding quality can be greatly improved by robot welding, the application of the arc welding robot is more and more extensive. However, for the welding of a thick plate special-shaped structure, the welding of an arc welding robot has many difficulties, mainly including:

(1) when a thick plate is T-connected, a K-shaped groove is opened to carry out multilayer and multi-pass welding, and programming is generally carried out in an online teaching or offline programming mode. The online teaching time is long, and the efficiency is low; during off-line programming, welding deformation is caused in the welding hot process, on-site deviation correction is often needed, a reliable tracking mode for automatic deviation correction is not available at present, and manual deviation correction is needed, so that the production efficiency is low;

(2) along with the increase of the thickness of the thick plate, the area of the groove is sharply increased, the number of welding tracks on each layer is increased, the cleaning between the tracks needs long time, and the non-fusion between the tracks is easy to form;

(3) the traditional K-shaped groove is adopted for multilayer and multi-pass welding, the welding quantity is huge, and due to the huge structure of hydroelectric equipment and limited welding space, the linkage of multiple robots cannot be realized, and the production output of one or two robots cannot be brought into a normal production flow;

(4) the welding of special-shaped structural parts has irregular welding bead and complex programming, and the accuracy of the track of the robot cannot be ensured, so that the welding bead is not formed well.

Therefore, the robot welding device cannot be widely used for robot welding of thick plates and ultra-thick plates with special-shaped structures all the time.

Disclosure of Invention

The invention aims to solve the problems that in the prior art, a T-shaped welding joint adopts a conventional K-shaped groove design, so that the welding bead is irregular, the planning difficulty of the welding bead is high, and the non-fusion between the welding beads is easy to form during multi-layer and multi-channel welding. According to the invention, the butt joint groove between the special-shaped structure thick plate and the plane thick plate is changed, namely a rectangular structure is processed within a range of 60mm above the welding end of the special-shaped thick plate, the arc welding bead is changed into a linear welding bead, the welding track of a robot can be simplified, the programming difficulty is reduced, an oblique welding surface with a certain inclination is arranged on the welding surface of the rectangular structure, the welding groove between the special-shaped thick plate and the plane thick plate is designed into an I-shaped narrow gap groove structure, the original multi-layer multi-pass welding is changed into one layer, the welding process is simplified, the probability of incomplete fusion between the welding beads and the times of cleaning the welding bead are reduced, and the welding.

In order to solve the problems in the prior art, the invention is realized by the following technical scheme:

the thick-section narrow-gap T-shaped welding method is characterized in that: the method comprises the following steps:

groove designing step: processing the special-shaped thick plate into a rectangular structure within a range of 60mm above the welding end of the special-shaped thick plate, wherein the width of the rectangular structure is not less than the maximum width of the special-shaped thick plate; the welding surface of the rectangular structure is an oblique welding surface with a certain inclination to form an I-shaped narrow gap groove structure, the gap between the root part of the I-shaped narrow gap groove and the plane thick plate is less than 16mm, and the gap between the upper end of the I-shaped narrow gap groove and the plane thick plate is less than 20 mm; a conventional K-shaped groove is formed in each of two ends of the special-shaped thick plate in a certain length, and a certain gap is reserved between the K-shaped groove and the I-shaped narrow gap groove;

assembling: assembling the special-shaped thick plate on the plane thick plate;

positioning welding and block lapping: assembling a plurality of blocks on the non-welding side of the special-shaped thick plate, welding and positioning welding the K-shaped groove part, and performing fillet welding on the blocks;

a welding track generation step of the welding robot: planning a welding track of the welding robot in a computer control system according to the relation among the size, the assembly and the position of the workpiece; carrying the L-shaped narrow gap welding torch on the execution end of the welding robot;

preheating before welding: preheating a bottom welding bead of a welded workpiece by using a far infrared electric heating device or flame;

a welding step: according to the size, assembly and position relation of a workpiece, the position of a moving platform outside the welding robot and the posture of a welding robot body are adjusted, so that a welding torch body of the L-shaped narrow gap welding torch is positioned in the middle of a groove and is perpendicular to the plane of the narrow gap groove, and the posture of the welding torch is consistent with that of a welding track during planning; and executing the automatic welding track of the welding robot planned in the welding track generation step of the welding robot, fusing the two side walls of the groove by utilizing the swinging of the L-shaped welding torch contact nozzle, and welding.

In the pre-welding preheating step, the preheating temperature is 80-150 ℃.

And an auxiliary support piece is machined at the root part of the type I narrow gap groove.

The L-shaped narrow gap welding torch comprises a transmission mechanism and a welding torch main body, wherein the transmission mechanism is connected with one end of the welding torch main body, so that the overall appearance of the welding torch structure is L-shaped; the welding torch main body is of a straight structure; the welding torch main body comprises a rotary conductive mechanism, a nozzle cooling mechanism, a main conductive rotating rod, a nozzle, a conductive nozzle and a welding torch body, wherein the main conductive rotating rod is arranged in the welding torch body, and the rotary conductive mechanism is arranged at the end part of the welding torch body and is connected with the main conductive rotating rod to supply power to the main conductive rotating rod; the transmission mechanism is connected with the main conductive rotating rod and drives the main conductive rotating rod to rotate; the nozzle is arranged at the other end of the welding torch body, and the end part of the main conductive rotating rod is connected with the conductive nozzle and is positioned in the nozzle; the nozzle cooling mechanism is disposed inside the torch body for cooling the nozzle.

The transmission mechanism comprises a servo motor, a speed reducer and a bevel gear set, the bevel gear set comprises two conical transmission gears, one conical transmission gear is arranged on the main conductive rotating rod, the other conical transmission gear is arranged on an output shaft of the speed reducer, and the servo motor is driven by the speed reducer to decelerate and drives the main conductive rotating rod to rotate by the transmission of the bevel gear set.

The conductive nozzle and the main conductive rotating rod form a certain angle, and the certain angle is 10-12 degrees.

The welding wire is arranged in the contact tube, and the length of the welding wire extending out of the contact tube is 17-20 mm.

The nozzle cooling mechanism is a water cooling channel arranged inside the welding torch body.

And the outer surface of the welding torch main body is sprayed with high-temperature-resistant insulating ceramic.

The nozzle is made of chromium-zirconium-copper materials, and high-temperature-resistant insulating ceramics are sprayed on the contact part of the end part of the welding torch body and the nozzle and are fixed by insulating screws.

Compared with the prior art, the beneficial technical effects brought by the invention are as follows:

1. the welding groove is processed into a rectangular structure within the range of 60mm above the welding end of the special-shaped thick plate, the arc welding bead is changed into the linear welding bead, the welding track of the welding robot can be simplified, the programming difficulty is reduced, the welding surface of the rectangular structure is set into an oblique welding surface with a certain inclination, the welding groove between the special-shaped thick plate and the plane thick plate is designed into an I-shaped narrow-gap groove structure, the original multilayer and multi-pass welding is changed into one-layer one-pass welding, the welding process is simplified, the non-fusion probability among the welding beads and the times of cleaning the welding beads are reduced, and the welding efficiency.

2. The invention respectively arranges K-shaped grooves with certain length at two ends of the special-shaped thick plate for positioning welding, the length of the K-shaped grooves can be determined according to the actual working condition, a certain gap is reserved between the K-shaped grooves and the narrow-gap grooves, and the flat welding torch extends to the gap part during welding, so that the contact tip in the middle of the welding torch can reach the end part of the narrow-gap grooves.

3. The invention has the innovation point that the welding end of the thick plate with the special-shaped structure is changed into a linear type from a special shape, and the T-shaped joint of the thick plate is changed into an I-shaped groove from a K-shaped groove. The advantages after the change are that: the welding end of the thick plate with the special-shaped structure is changed into a linear type from special shape, so that the welding path track can be simplified. The thick plate T-shaped joint is changed from a K-shaped groove to an I-shaped groove, multilayer multi-pass welding is changed into single-pass one-pass welding, welding pass planning is simplified, the phenomenon that fusion does not occur between welding passes is avoided, welding pass cleaning is reduced, welding quantity is reduced by more than 60%, and welding efficiency is improved.

4. According to the invention, the auxiliary supporting piece is processed at the root part of the similar I-shaped narrow gap groove, so that the positioning of the special-shaped thick plate is convenient, and the welding is convenient.

5. The welding torch structure can effectively avoid the interference between the welding torch and the plane thick plate, the welding torch main body is of a straight structure and is parallel to the plane part in the T-shaped welding joint, and the problems of structural rigidity deterioration and unstable electric arc can be effectively solved. Torch cooling is mainly composed of contact tip cooling and nozzle cooling. The cooling of the contact nozzle is realized by a cooling water channel contained in the welding torch body, the welding torch body is of a solid aluminum alloy metal structure, two water channels are drilled in the welding torch body, the welding torch body is cooled through water cooling, and after the temperature of the contact nozzle is transferred to the main conductive rotary rod, the main conductive rotary rod conducts heat with the welding torch body in a contact heat transfer mode and is taken out by cooling water, so that the cooling of the contact nozzle is realized. The two nozzles of the welding torch are cooled by cooling water cooled by the two nozzles respectively.

6. The inner part of the welding torch body is additionally drilled with two paths of protective gas to lead the protective gas to the nozzle. The main conductive rotating rod is in arc contact with the rotary conductive mechanism, and the contact still exists when the main conductive rotating rod rotates. When the external power supply is connected to the rotary conductive mechanism, the power supply is transmitted to the main conductive rotary rod in rotation and is transmitted to the contact tip. The outer surface of the welding torch main body is sprayed with high-temperature-resistant insulating ceramic for electrical insulation, the welding torch main body can be used for a long time in a high-temperature environment, the hardness of the ceramic material is high, and the use is not affected after the ceramic material is slightly scratched on the side wall of a welding seam. The nozzle is made of chromium zirconium copper, and the contact part of the end part of the welding torch body and the nozzle is sprayed with high-temperature-resistant insulating ceramic and is fixed by adopting an insulating screw.

7. The welding wire is bent by a contact tube inclined by 10-12 degrees, the contact tube of the welding wire is always kept straight, the welding wire swings stably, and the electric arc is stable. The two 90-degree bevel gear transmission structures are connected, so that the power of the servo motor is transmitted to the main conductive rotating rod, and the conductive nozzle arranged on the main conductive rotating rod can rotate 360 degrees infinitely.

8. The welding torch is L-shaped as a whole, the main body of the welding torch is of a straight structure and is parallel to the plane part in the T-shaped joint, and the welding torch is cooled by water as a whole, so that the service lives of the nozzle, the contact tip and the welding torch body are prolonged. The welding torch adopts a special bevel gear transmission mechanism, the main rotating conductive nozzle rod can infinitely rotate for 360 degrees, and the angle of the conductive nozzle can be adjusted at will.

9. Aiming at the characteristics and difficulties of the T-shaped joint of the thick plate with the special-shaped structure, the invention develops the L-shaped narrow gap welding torch suitable for the T-shaped joint through the innovative change of the groove structure, and carries the L-shaped narrow gap welding torch on the arc welding robot, thereby realizing the intelligent narrow gap welding of the T-shaped joint of the thick plate with the special-shaped structure, simplifying the welding path track and the welding path planning, reducing the difficulty in programming the welding program of the robot, greatly reducing the welding quantity, improving the welding efficiency of the robot, simultaneously stabilizing the welding quality and reducing the dependence on manual welding by adopting the intelligent welding of the robot.

10. Aiming at the welding difficulty of T-shaped joints of thick plates and ultra-thick plates with special-shaped structures, the invention is developed from a welding structure, changes the conventional multi-layer multi-pass welding of K-shaped large grooves into single-layer one-pass welding of I-shaped grooves, greatly reduces the welding deposition amount, improves the welding efficiency, shortens the welding period and improves the welding quality. The L-shaped narrow gap welding torch suitable for welding the T-shaped joint is developed, so that the welding robot is suitable for I-shaped narrow gap groove welding of T-shaped joints of thick plates and ultra-thick plates, the L-shaped narrow gap welding torch is carried at the tail end of an arc welding robot, intelligent narrow gap welding of T-shaped joints of thick plates and ultra-thick plates with special-shaped structures is realized, the welding quality is improved, the welding operation environment is improved, and a new idea is developed for the robot in the heavy machinery manufacturing industry.

11. According to the invention, the thick plate T-shaped joint is changed from a K-shaped large groove to an approximate I-shaped narrow gap groove, multilayer multi-pass welding is changed into single-layer one-pass welding, welding bead planning is simplified, the occurrence of incomplete fusion between welding beads is avoided, welding bead cleaning is reduced, the welding quantity is reduced by more than 60%, and the welding efficiency is improved; the welding end of the thick plate with the special-shaped structure is changed into a linear type from a special shape, so that the planning of a welding path track is simplified; the welding of the narrow groove of the T-shaped joint is realized through the design of the L-shaped narrow gap welding torch; the L-shaped narrow-gap welding torch is carried on the arc welding robot, so that the robot intelligent narrow-gap welding of the ultra-thick section of the special-shaped structural part is realized, the welding quality is improved, the manual operation environment is improved, and the welding period is greatly shortened.

Drawings

FIG. 1 is a schematic structural view of the assembly of a special-shaped thick plate and a plane thick plate;

FIG. 2 is a schematic structural diagram of a welding end of a specially-shaped thick plate;

FIG. 3 is a schematic structural view of a conventional K-groove in the prior art;

FIG. 4 is a schematic structural view of a type I narrow gap groove of the present invention;

FIG. 5 is a schematic view of a narrow gap groove structure after the special-shaped thick plate and the planar thick plate are assembled according to the present invention;

FIG. 6 is a schematic structural view of a narrow gap T-joint of the present invention;

FIG. 7 is a schematic top view of a torch in accordance with the present invention;

FIG. 8 is a schematic side view of a torch of the present invention;

FIG. 9 is a schematic structural view of a torch drive mechanism according to the present invention;

FIG. 10 is a schematic view of the torch of the present invention rotated;

FIG. 11 is a schematic diagram of a narrow gap MAG welding method of the present invention;

FIG. 12 is a view of a turbine shroud assembly configuration;

FIG. 13 is a view of a turbine seat ring robot narrow gap welding position 1;

FIG. 14 is a view of a turbine seat ring robot narrow gap welding position 2;

FIG. 15 is a schematic view of the present invention performing thick section narrow gap welding;

reference numerals: 1. the special-shaped thick plate comprises a special-shaped thick plate body, 2, a plane thick plate body, 3, an auxiliary supporting piece, 4, an oblique welding surface, 5, a fixed guide vane, 6, a ring plate, 7 and a lapping block, wherein a represents a gap between the root of a similar I-shaped narrow gap groove and the plane thick plate body, b represents a gap between the upper end of the similar I-shaped narrow gap groove and the plane thick plate body, L1 represents a rectangular structure, L2 represents a gap between a K-shaped groove and the similar I-shaped narrow gap groove, L3 represents a K-shaped groove, d1 represents the section shape of the special-shaped thick plate body, and d2 represents the section shape;

11. the welding robot comprises a transmission mechanism, 12, a welding torch main body, 13, a rotary conducting mechanism, 14, a nozzle cooling mechanism, 15, a main conducting rotary rod, 16, a nozzle, 17, a contact tip, 18, a welding torch body, 19, a servo motor, 110, a speed reducer, 111, a bevel gear set, 112, a welding wire, 113 and a welding robot, wherein c represents an angle between the contact tip and the main conducting rotary rod, d represents a swinging angle of the contact tip, and L represents the length of the welding wire extending out of the contact tip.

Detailed Description

The technical scheme of the invention is further elaborated in the following by combining the drawings in the specification.

Example 1

As a preferred embodiment of the present invention, the present embodiment discloses:

groove designing step: processing the special-shaped thick plate into a rectangular structure within the range of 60mm above the welding end of the special-shaped thick plate, wherein the width of the rectangular structure is not less than the maximum width of the special-shaped thick plate 1; the welding surface of the rectangular structure is an oblique welding surface 4 with a certain inclination to form an I-shaped narrow gap groove structure, the gap between the root part of the I-shaped narrow gap groove and the plane thick plate 2 is less than 16mm, and the gap between the upper end of the I-shaped narrow gap groove and the plane thick plate 2 is less than 20 mm; a conventional K-shaped groove is formed in each of two ends of the special-shaped thick plate 1 in a certain length, and a certain gap is reserved between the K-shaped groove and the I-shaped narrow gap groove;

assembling: assembling the special-shaped thick plate 1 on the plane thick plate 2;

positioning welding and block lapping: assembling a plurality of overlapping blocks 7 on the non-welding side of the special-shaped thick plate 1, welding and positioning welding on the K-shaped groove part, and performing fillet welding on the overlapping blocks 7;

welding robot 113 welding trajectory generation step: planning the welding track of the welding robot 113 in a computer control system according to the relation among the size, assembly and position of the workpiece; the L-shaped narrow gap welding torch is carried at the execution end of the welding robot 113;

a welding step: according to the size, assembly and position relation of the workpiece, the position of a moving platform outside the welding robot 113 and the posture of the welding robot 113 body are adjusted, so that the L-shaped narrow-gap welding torch body 18 is positioned in the middle of the groove and is perpendicular to the plane of the narrow-gap groove, and the posture of the welding torch is consistent with that of the welding track during planning; the welding robot 113, which is planned in the welding locus generation step of the welding robot 113, executes the automatic welding locus, and the two side walls of the groove are fused by the swing of the L-shaped torch contact tip 17 to perform welding.

Example 2

Referring to fig. 1-6 of the specification, this embodiment discloses as another preferred embodiment of the present invention:

preheating before welding: preheating a bottom welding bead of a welded workpiece by using a far infrared electric heating device or flame; the preheating temperature is 80-150 ℃;

a welding step: according to the size, assembly and position relation of the workpiece, the position of a moving platform outside the welding robot 113 and the posture of the welding robot 113 body are adjusted, so that the L-shaped narrow-gap welding torch body 18 is positioned in the middle of the groove and is perpendicular to the plane of the narrow-gap groove, and the posture of the welding torch is consistent with that of the welding track during planning; the welding robot 113, which is planned in the welding locus generation step of the welding robot 113, executes the automatic welding locus, and the two side walls of the groove are fused by the swing of the L-shaped torch contact tip 17 to perform welding. And an auxiliary support piece 3 is processed at the root part of the type I narrow gap groove.

Example 3

Referring to fig. 1-11 of the specification, this embodiment discloses:

the use of the welding robot 113 is the direction of future manufacturing. Aiming at the robot welding of thick plates and ultra-thick plates with special-shaped structures, the welding quality and efficiency of an arc welding robot need to be improved. Therefore, the welding groove of the thick plate and the ultra-thick plate is changed by changing the welding structure of the product, the novel welding technology is carried on the arc welding robot, and the welding quantity of the ultra-thick section structural member is reduced, so that the welding efficiency of the arc welding robot is increased, and the novel intelligent welding field of the arc welding robot in the power generation equipment hydropower industry is developed.

The narrow gap gas shielded welding technology is a novel welding technology and mainly has the following advantages:

(1) the deposition efficiency is high, and the clearance is small (mostly 10-16 mm), so the production efficiency is higher;

(2) the heat input is moderate, the adjusting range is large, and the welding device is suitable for welding various metals; the preheating temperature can be reduced, and preheating and post-heating can be omitted for medium-strength steel;

(3) the welding device is suitable for flat welding, transverse welding and all-position welding, and the limit thickness of the welding is larger and is generally 300 mm.

(4) And the slag removal between welding beads is simple.

The narrow gap gas shielded welding technology is connected with the arc welding robot, so that the welding efficiency of the arc welding robot can be greatly improved, one or two high-quality and high-efficiency welding of a deep narrow groove single layer is realized, and the risk of poor fusion during multi-layer and multi-channel welding of an ultra-thick section is avoided.

The technical scheme adopted by the invention is as follows: the groove structure of the welding end of the special-shaped structural member is changed, the arc groove is changed into a linear groove, the K-shaped groove of the T-shaped joint is changed into an I-shaped groove, and the special L-shaped narrow gap welding torch loaded at the tail end of the arc welding robot is adopted for carrying out robot 113 narrow gap welding.

1. Groove design: the T-shaped joint of the thick plate with the special-shaped structure generally comprises two structural parts, as shown in an attached figure 1 of the specification, wherein 1 is a special-shaped thick plate with an ultra-thick section, 2 is a plane thick plate 2, and a welding groove of the joint is formed in a special-shaped thick plate 11, so that groove design is mainly performed on the special-shaped thick plate 11. The sectional shape of the special-shaped thick plate 11 is shown as d1 in fig. 2, the conventional groove is a K-shaped groove, and a T-shaped joint is formed with the plane thick plate 22, as shown in fig. 3, the structural groove is huge, and the weld bead profile is irregular. Generally adopt artifical welding or the welding of robot 113 in the conventional welding, carry out multilayer multi-pass welding, artifical welding amount of labour is big, when adopting the welding of robot 113, because the welding bead is irregular, the welding bead planning degree of difficulty is big, and during multilayer multi-pass welding, the extremely easy formation between the way does not fuse.

The technical scheme adopted by the invention is as follows: processing to the rectangle structure in 60mm within range above the welding end of special-shaped thick plate 1, changing the arc welding bead into the linear welding bead, simplifying welding robot 113 welding track, reducing the programming degree of difficulty, as d2 in fig. 2. A certain inclined plane is arranged at the part of the rectangle L1 to form a similar I-shaped narrow gap groove structure, as shown in figures 4 and 5, the root part a of the narrow gap groove is smaller than 16mm, and the upper end b of the narrow gap groove is smaller than 20mm, one-layer narrow gap welding is carried out, the original multi-layer multi-pass welding is changed into one-layer one-pass welding, the welding process is simplified, the probability of incomplete fusion between welding passes and the times of cleaning the welding passes are reduced, and the welding efficiency is improved. Conventional K-shaped grooves are formed in two ends of the fixed guide vane 5 in a certain length for positioning welding, a certain gap is reserved between the K-shaped grooves and the narrow-gap grooves, and a flat welding torch extends to the gap part during welding, so that the conductive nozzle 17 in the middle of the welding torch can reach the end part of the narrow-gap groove.

The technical scheme of the invention is innovatively changed by two points: (1) changing the welding end of the thick plate with the special-shaped structure from special shape to linear shape; (2) the T-shaped joint of the thick plate is changed from a K-shaped groove to an approximate I-shaped groove. The advantages after the change are: (1) the welding end of the thick plate with the special-shaped structure is changed into a linear type from a special shape, so that the welding path track is simplified. (2) The thick plate T-shaped joint is changed from a K-shaped groove to an approximate I-shaped groove, multilayer multi-pass welding is changed into single-layer one-pass welding, welding bead planning is simplified, the occurrence of incomplete fusion between welding beads is avoided, welding bead cleaning is reduced, welding quantity is reduced by more than 60%, and welding efficiency is improved.

2. Design of an L-shaped narrow gap welding torch: the narrow-gap gas metal arc welding technology is a novel welding technology, has certain application in the field of nuclear power structures at present, is mainly applied to butt joint grooves, and is characterized in that a welding torch structure is generally T-shaped, and the maximum welding depth is generally 300 mm. However, when the dimension of the welding end L of the flat thick plate 21 in the T-shaped joint is larger than 500mm, the structural rigidity of the T-shaped torch is deteriorated, and the arc is unstable during welding, so that the structural narrow gap torch is extremely unsuitable for narrow groove welding of the T-shaped joint. In order to realize the narrow-gap groove welding of the T-shaped joint, the welding torch needs to be redesigned.

2.1 torch configuration: to achieve narrow gap welding of the T-shaped structure, it is necessary to arrange the parts other than the torch main body 12 on the item 2 side in fig. 6 and avoid interference of the torch with the item 1. Therefore, the welding torch is designed to be L-shaped and comprises two parts, namely an item 11 and an item 12 in fig. 8, wherein the item 12 is a welding torch main body 12 which extends into a narrow gap groove during welding, and the item 11 is a contact tip 17 control part which is positioned on the item 2 side in fig. 6 during welding. Item 12 essentially comprises a rotating electrical conducting means 13, a nozzle cooling means 14, a leading wire rotating stem, a nozzle 16, a contact tip 17 and a torch body 18.

Cooling the welding torch: mainly consists of contact tip 17 cooling and nozzle 16 cooling. The cooling of the contact tip 17 is realized by a cooling water channel contained in the welding torch body 18, the welding torch body 18 is of a solid aluminum alloy metal structure, two water channels are drilled in the welding torch body, the welding torch body 18 is cooled through water cooling, and after the temperature of the contact tip 17 is transmitted to the main conductive rotating rod 15, the main conductive rotating rod 15 and the welding torch body 18 conduct heat in a contact heat transfer mode and are taken out by cooling water, so that the cooling of the contact tip 17 is realized. The two nozzles 16 of the welding torch are cooled by the cooling water of the two nozzle cooling mechanisms 14.

Gas protection: the torch body 18 is further bored with two shield gas passages to guide the shield gas to the nozzle 16.

Conducting electricity: the main conductive rotating rod 15 is in arc contact with the rotating conductive mechanism 13, and the contact still exists when the main conductive rotating rod 15 rotates. When an external power source is connected to the rotary conductive mechanism 13, the power source is transmitted to the main conductive rotary rod 15 in rotation and the power source is transmitted to the contact tip 17.

Insulation: the outer surface of the welding torch main body 12 is sprayed with high-temperature-resistant insulating ceramic for electrical insulation, the welding torch can be used for a long time in a high-temperature environment, the hardness of the ceramic material is high, and the use is not affected after the ceramic material is slightly scratched on the side wall of a welding seam. The nozzle 16 is made of chromium zirconium copper, and the contact part of the end part of the welding torch body 18 and the nozzle 16 is sprayed with high-temperature resistant insulating ceramic and fixed by using an insulating screw.

The contact tip 17 swings: the welding wire 112 is bent by the contact tip 17 inclined by 10-12 degrees, the contact tip 17 of the welding wire 112 is always kept in a straight state, the welding wire 112 swings stably, and the electric arc is stable. Item 11 is the swing control part of the contact tip 17, as shown in fig. 9, and includes a servo motor 19, a precision star reducer 110, and a bevel gear set 111.

Items

11 and 12 in fig. 8 are connected through two 90-degree bevel gear transmission structures, so that the power of the servo motor 19 is transmitted to the main guide wire rotating rod, and the 360-degree infinite revolution of the contact tip 17 installed on the main guide wire rotating rod is realized. Item 12 is a plane structure in the thickness direction, and forms an L-shaped narrow gap welding torch structure together with item 11.

The welding torch has the structural characteristics that: the welding torch is L-shaped as a whole, the welding torch main body 12 is of a straight structure and is parallel to the plane part in the T-shaped joint, and the welding torch is cooled by water as a whole, so that the service lives of the nozzle 16, the contact tip 17 and the welding torch body 18 are prolonged. The welding torch adopts a special bevel gear transmission mechanism 11, the main rotating contact nozzle 17 rod can rotate infinitely for 360 degrees, and the angle of the contact nozzle 17 can be adjusted randomly.

2.2 welding torch swinging principle: the servo motor 19 is controlled to rotate, the main conductive rotating rod 15 is driven to rotate through two 90-degree bevel gears (one is arranged on the motor, and the other is arranged on the main conductive rotating rod 15), the conductive nozzle 17 and the main conductive rotating rod 15 are eccentric by 10-12 degrees, and the rotation of the main conductive rotating rod 15 drives the conductive nozzle 17 to swing.

As shown in fig. 10, the contact tip 17 and the main conductive rotating rod 15 form an angle c, c is 10-12 °, the welding wire 112 extends out of the contact tip 17 by a length L, L is 17-20mm, and after the main conductive rotating rod 15 rotates, the contact tip 17 swings by an angle d, which can be any angle of 360 °.

2.3 principle of narrow gap MAG welding method: as shown in FIG. 11, the tip 17 is angled with respect to the main conductive rotating rod 15 and the welding wire 112 is threaded obliquely out of the front end of the torch. The rotation of the main conductive rotating rod 15 drives the welding wire 112 to swing left and right, so that the purpose of swinging left and right of the electric arc is realized in the welding process, and the left and right side walls of the narrow groove are effectively fused.

3. Welding the T-shaped joint robot 113 of the thick plate with the special-shaped structure in a narrow gap manner:

when the special-shaped structure thick plate adopts conventional K-shaped groove to carry out robot 113 welding, because the welding bead orbit is the arc, need set up sufficient track point and come to fit the orbit to the degree of difficulty of programming has been increased. And because the groove size is different when K type groove is at the different degree of depth, need plan multilayer multichannel welding bead, in case the deviation appears in the actual welding process in the well planned welding bead, need modify at any time, this greatly reduced the efficiency that robot 113 welded.

After the welding end of the thick plate with the special-shaped structure is changed into a linear type from the special shape, the welding path track is simplified, the walking track of the arc welding robot is changed into the linear type from the arc shape, and the welding programming of the robot 113 is greatly simplified. The K-shaped groove is changed into an approximate I-shaped groove, multilayer multi-pass welding is changed into single-layer one-pass welding, the welding path planning does not need to be changed according to the difference of the forming and welding quantity of each welding line of each layer, and the welding path planning is extremely simple.

Therefore, the technical scheme of the invention is as follows: and (3) after the groove of the special-shaped structural thick plate is changed from the groove design of item 1, carrying the L-shaped narrow gap welding torch in the L-shaped narrow gap welding torch design of item 2 on a welding robot, and carrying out intelligent narrow gap welding by the welding robot. The method comprises the following specific steps:

(1) processing the thick plate with the special-shaped structure according to the step 1;

(2) assembling the special-shaped structure thick plate 1 and the plane thick plate 22;

(3) positioning welding and block lapping 7 are carried out after assembly;

(4) generating an automatic welding track of the welding robot: and planning the welding track of the welding robot 113 in a computer control system by utilizing the solid modeling function of three-dimensional CAD software according to the size, assembly and position relation of each part of the seat ring. And (3) taking the three-dimensional model to two points at the arc starting position and the arc extinguishing position of each welding seam track, then respectively taking a gun inlet point and a gun outlet point, and completing the whole narrow-gap groove welding seam by the welding seam program through a circulating command.

(5) The L-shaped narrow gap torch is mounted on the tip of the welding robot 113, and a torch tip contact tip 17 swing control system is connected thereto.

(6) Preheating before welding: the bottom weld bead of the workpiece to be welded is preheated by a far infrared electric heating device or flame, and the preheating temperature is determined according to the material and the plate thickness of the workpiece and is usually 80-150 ℃.

(7) According to the size, assembly and position relation of the workpiece, the position of the external moving platform of the welding robot 113 and the posture of the welding robot 113 body are adjusted, so that the welding torch body 18 of the L-shaped narrow gap welding torch is positioned in the middle of the groove and is perpendicular to the plane of the narrow gap groove, and the posture of the welding torch is consistent with that of the welding track during planning. And (4) executing the automatic welding track of the welding robot 113 planned in the step (4), fusing the two side walls of the groove by utilizing the swinging of the contact tip 17 of the L-shaped narrow gap welding torch, and carrying out one-layer high-efficiency and high-quality welding.

Aiming at the characteristics and difficulties of the T-shaped joint of the thick plate with the special-shaped structure, the invention develops the L-shaped narrow gap welding torch suitable for the T-shaped joint through the innovative change of the groove structure, and carries the L-shaped narrow gap welding torch on an arc welding robot, thereby realizing the intelligent narrow gap welding of the T-shaped joint of the thick plate with the special-shaped structure, simplifying the welding path track and the welding path planning, reducing the difficulty in programming the welding program of the robot 113, greatly reducing the welding quantity, improving the welding efficiency of the robot 113, stabilizing the welding quality and reducing the dependence on manual welding by adopting the robot 113 to carry out intelligent welding.

Example 4

As another preferred embodiment of the present invention, referring to fig. 12-14 of the specification, the present embodiment discloses:

the application of the thick plate T-shaped joint robot 113 narrow gap welding technology in the water turbine seat ring is as follows: the seat ring mainly comprises a fixed guide vane 5 and a ring plate 6, the thickness of the fixed guide vane 5 can reach 270mm at most, and the thickness of the ring plate 6 can reach 250mm at most.

1. Groove machining: the welding bevel of the seat ring fixed guide vane 5 and the ring plate 6 is arranged at the end part of the fixed guide vane 5, so the bevel design is mainly carried out on the fixed guide vane 5. The section of the fixed guide vane 5 is of a special-shaped structure, the fixed guide vane is processed to a rectangular structure within the range of 60mm above a welding end, a certain inclined plane is arranged on the rectangular part to form an approximate I-shaped narrow gap groove structure, the root part a of the narrow gap groove is smaller than 16mm, the upper end b of the narrow gap groove is smaller than 20mm, conventional K-shaped grooves are respectively formed in two ends of the fixed guide vane 5 by certain lengths, and a certain gap is reserved between the K-shaped grooves and the narrow gap grooves.

2. Assembling a seat ring: when the conventional seat ring is welded, the two petal seat rings are assembled together in a way that the back surfaces and the opposite surfaces of the two petal seat rings are assembled together by adopting a butt strap so as to control the welding deformation. Compared with the conventional K-shaped groove, the groove size is reduced by 60% when narrow gap welding is adopted, and the welding amount and the welding deformation are correspondingly reduced, so that the method is different from the conventional seat ring assembly.

(1) Marking on the ring plate 6 according to the drawing of the product;

(2) assembling the fixed guide vane 5 according to the marking and the simulation result of the welding of the robot 113;

(3) two blocks 7 are respectively assembled on the upper side and the lower side of the non-welding side of the fixed guide vane 5 to control welding deformation;

(4) and (6) positioning and welding. Welding and positioning welding on the K-shaped groove part, wherein the welding quantity is 20 mm;

(5) and the block 7 is welded. Fillet welding is carried out on the lapping block 7, and the welding leg is 20 mm.

(6) The robot 113 automatically simulates the welding track: and planning the welding position of each guide vane and the welding track of the robot 113 in a computer control system by using the solid modeling function of three-dimensional CAD software according to the size, assembly and position relation of each part of the seat ring.

(7) And placing the seat ring on the welding platform according to the computer simulation result.

3. Seat ring welding:

(1) preheating before welding: the bottom weld bead of the workpiece to be welded is preheated by a far infrared electric heating device or flame, and the preheating temperature is determined according to the material and the plate thickness of the seat ring part and is usually 80-150 ℃.

(2) Robot 113 welding programming: and calibrating the base of the workpiece according to the position of the workpiece, and compiling the actual welding track of the robot 113.

(3) As shown in fig. 15, a flat welding torch is inserted into the I-shaped narrow gap groove to perform one-layer or two-layer high-efficiency and high-quality welding, after each welding pass is completed, the welding pass is cleaned by a steel wire brush, and after each two-layer welding pass is completed, the welding pass is cleaned by a pneumatic shovel to remove slag.

(4) And (3) welding sequence: when the welding filling amount of the groove of the single fixed guide vane 5 reaches a certain thickness, the welding position of the welding robot 113 is adjusted, another fixed guide vane 5 is welded, and the fixed guide vanes 5 at the position are welded to a certain thickness in sequence. Turning over, welding the fixed guide vane 5 at the other position, and completing welding of the welding seam of the fixed guide vane 5 at the position. Turning over, putting the guide vane to the original position, and welding all welding seams of the lower fixed guide vane 5 at the position.

Claims

1. The thick-section narrow-gap T-shaped welding method is characterized in that: the method comprises the following steps:

groove designing step: processing the special-shaped thick plate (1) into a rectangular structure within a range of 60mm above the welding end, wherein the width of the rectangular structure is not less than the maximum width of the special-shaped thick plate (1); the welding surface of the rectangular structure is an oblique welding surface (4) with a certain inclination to form an I-shaped narrow gap groove structure, the gap between the root of the I-shaped narrow gap groove and the plane thick plate (2) is less than 16mm, and the gap between the upper end of the I-shaped narrow gap groove and the plane thick plate (2) is less than 20 mm; a conventional K-shaped groove is formed in each of two ends of the welding end of the special-shaped thick plate (1) in a certain length, and a certain gap is reserved between the K-shaped groove and the I-shaped narrow gap groove;

assembling: assembling the special-shaped thick plate (1) on the plane thick plate (2);

positioning welding and block lapping: assembling a plurality of blocks on the non-welding side of the special-shaped thick plate (1), welding and positioning welding on the K-shaped groove part, and performing fillet welding on the blocks;

a welding robot (113) welding track generation step: planning the welding track of the welding robot (113) in a computer control system according to the relation among the size, the assembly and the position of the workpiece; the L-shaped narrow gap welding torch is arranged at the execution end of the welding robot (113);

a welding step: according to the size, assembly and position relation of a workpiece, the position of an external moving platform of the welding robot (113) and the posture of a welding robot (113) body are adjusted, so that a welding torch body (18) of the L-shaped narrow gap welding torch is positioned in the middle of the groove and is perpendicular to the plane of the narrow gap groove, and the posture of the welding torch is consistent with that of a welding track during planning; and executing the automatic welding track of the welding robot (113) planned in the welding track generation step of the welding robot (113), fusing the two side walls of the groove by utilizing the swinging of a contact tip (17) of the L-shaped narrow gap welding torch, and welding.

2. A thick section narrow gap T-shaped welding method as claimed in claim 1, characterized in that: in the pre-welding preheating step, the preheating temperature is 80-150 ℃.

3. A thick section narrow gap T-shaped welding method as claimed in claim 1, characterized in that: and an auxiliary support piece (3) is machined at the root part of the type I narrow gap groove.

4. A thick section narrow gap T-shaped welding method as claimed in claim 1, characterized in that: the L-shaped narrow gap welding torch comprises a transmission mechanism (11) and a welding torch main body (12), wherein the transmission mechanism (11) is connected with one end of the welding torch main body (12), so that the overall appearance of the welding torch structure is L-shaped; the welding torch main body (12) is of a straight structure; the welding torch main body (12) comprises a rotary conductive mechanism (13), a nozzle cooling mechanism (14), a main conductive rotating rod (15), a nozzle (16), a conductive nozzle (17) and a welding torch body (18), wherein the main conductive rotating rod (15) is arranged inside the welding torch body (18), and the rotary conductive mechanism (13) is arranged at the end part of the welding torch body (18) and connected with the main conductive rotating rod (15) to supply power to the main conductive rotating rod (15); the transmission mechanism (11) is connected with the main conductive rotating rod (15) to drive the main conductive rotating rod (15) to rotate; the nozzle (16) is arranged at the other end of the welding torch body (18), and the end of the main conductive rotating rod (15) is connected with the contact tip (17) and is positioned in the nozzle (16); the nozzle cooling mechanism (14) is disposed inside the torch body (18) for cooling the nozzle (16).

5. A thick section narrow gap T-shaped welding method as claimed in claim 4, characterized in that: the transmission mechanism (11) comprises a servo motor (19), a speed reducer (110) and a bevel gear set (111), the bevel gear set (111) comprises two conical transmission gears, one conical transmission gear is arranged on the main conductive rotating rod (15), the other conical transmission gear is arranged on an output shaft of the speed reducer (110), and the servo motor (19) is driven by the speed reducer (110) in a speed reducing mode and drives the main conductive rotating rod (15) to rotate through the transmission of the bevel gear set (111).

6. A thick section narrow gap T-shaped welding method as claimed in claim 4, characterized in that: the contact nozzle (17) and the main conductive rotating rod (15) form a certain angle, and the certain angle is 10-12 degrees.

7. A thick section narrow gap T-shaped welding method as claimed in claim 4, characterized in that: a welding wire (112) is arranged in the contact tip (17), and the length of the welding wire (112) extending out of the contact tip (17) is 17-20 mm.

8. A thick section narrow gap T-shaped welding method as claimed in claim 4, characterized in that: the nozzle cooling mechanism (14) is a water cooling channel disposed inside the torch body (18).

9. A thick section narrow gap T-shaped welding method as claimed in claim 4, characterized in that: the outer surface of the welding torch main body (12) is sprayed with high-temperature-resistant insulating ceramic.

10. A thick section narrow gap T-shaped welding method as claimed in claim 4, characterized in that: the nozzle (16) is made of chromium zirconium copper, and the contact part of the end part of the welding torch body (18) and the nozzle (16) is sprayed with high-temperature-resistant insulating ceramic and fixed by adopting an insulating screw.