CN114515889A - Welding device and method for rotary argon arc welding of small-caliber thin-wall bent pipe - Google Patents

Abstract

A welding device and method for rotary argon arc welding of small-diameter and thin-walled elbows. The device includes a welding torch holder, a rotary table, a DC power source and a welding table. The welding method includes the following steps: selecting welding materials, cutting materials, and slope Mouth processing, pre-weld assembly, pre-weld debugging, test piece welding and testing, formal welding, post-weld insulation, and penetration testing. The beneficial effects of the invention are as follows: in order to balance the heat input in the welding process of two workpieces of unequal thickness, the tungsten electrode is offset from the position to be welded by a certain distance to the thick workpiece, and the manual argon arc welding is improved to continuous Pulse argon arc welding, decomposes the circumferential weld into five zones, sets the welding current and welding time in different zones, balances the welding heat input of the whole circumferential weld, and avoids the weld hot cracks and crystallites that occur in the manual argon arc welding process. Coarse grains, inconsistent penetration and other defects, and at the same time, the production of welding equipment to achieve continuous rotary argon arc welding improves the appearance of argon arc welding weld formation, thereby ensuring the reliability of weld quality.

Description

A welding device and method for rotary argon arc welding of small diameter and thin-walled elbows

technical field

The invention relates to the technical field of welding technology, in particular to a welding device and method for rotary argon arc welding of small-diameter and thin-walled elbows.

Background technique

As one of the accessories of the aero-engine ignition system, the ion flame detector is mainly used to detect whether the afterburner of the engine is ignited. The ion flame detector is connected into a whole by the welding process of the electrode core column made of GH3044 (Φ12) and the elbow (Φ11.5×0.75) of material GH2747. Because the ion flame detector is a cantilever beam structure, it is limited by space during the rotation process. The manual tungsten argon arc welding method cannot achieve continuous welding for one week. It takes multiple arcs to complete the welding, and the quality of the weld is greatly affected by human operations. , resulting in poor weld formation, hot cracks, coarse grains, inconsistent penetration and other defects at the weld. Seriously affect the reliability of engine use.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned technical problems, the present invention provides a welding device and method for rotary argon arc welding of small diameter and thin-walled elbows, which are suitable for the welding of small-diameter thin-walled elbows of cantilever beam structures and rods of the same diameter. In rotary argon arc welding, in the welding process, in order to balance the heat input of two workpieces of unequal thickness, the tungsten electrode is offset from the position to be welded by a distance S=(0.5-1) mm. The manual argon arc welding is improved to continuous pulse argon arc welding, the circumferential weld is decomposed into five zones, the welding current and welding time of different zones are set, and the welding heat input of the whole circumference weld is balanced, which solves the problem of manual argon arc welding. The defects such as hot cracks, coarse grains and inconsistency in the penetration depth of the welding seam appear in the method. At the same time, the welding device is fabricated to realize the continuous rotary argon arc welding, which improves the appearance of the argon arc welding seam forming, thereby ensuring the reliability of the welding seam quality.

The present invention adopts the following technical scheme: a welding device for rotary argon arc welding of small diameter and thin-walled elbows, comprising: a welding torch holder, a rotating workbench, a DC power supply and a welding workbench, and is characterized in that: a welding torch holder, a rotating The workbench and the DC power supply are respectively placed on the welding workbench. The DC power supply is connected to the servo motor on the rotating workbench, which is used to supply power to the servo motor to drive the gear to rotate. The welding torch fixing frame is used to fix the welding torch and adjust the position of the welding torch to ensure that the welding torch is located in the position of the welding torch. Above the rotary table.

Further, the welding torch fixing frame includes an X-axis adjustment clamp, a Y-axis adjustment clamp, a Z-axis adjustment clamp, an R-axis adjustment clamp, an X-axis support frame, a Y-axis support frame, a Z-axis support frame and a welding torch clamp. The tightening mechanism can realize the welding torch clamping and the adjustment of the X, Y, Z, R axis directions; the Z axis support frame is fixed on the welding table, the Z axis adjustment clamp is sleeved on the Z axis support frame, and the Z axis support frame is vertical Connect the R-axis, the R-axis adjustment clamp is sleeved on the R-axis, the R-axis is vertically connected to the X-axis support frame, the X-axis adjustment clamp is sleeved on the X-axis support frame, the X-axis support frame is vertically connected to the Y-axis support frame, and the Y-axis The adjustment clamp is sleeved on the Y-axis support frame, the Y-axis support frame is connected to the welding gun clamping mechanism, and the welding gun clamping mechanism is connected to the welding gun.

Further, the rotary table includes a table bracket, a servo motor, a first transmission gear, a second transmission gear, a fixed nut, a boss, a buckle and a red copper twin; the worktable bracket is screwed on the welding table through the fixed nut, The servo motor is installed on the worktable bracket, the second transmission gear is tightened and fixed with the servo motor, the first transmission gear is located above the second transmission gear, the boss is located on the side of the first transmission gear, and is snapped right above the worktable bracket. The tire is located between the clip and the workbench bracket.

Further, the DC power supply is connected to the foot switch through a power supply line. The DC power supply is equipped with a foot switch to control the power on and off of the motor during the welding process, which is convenient for the welder to operate.

Further, a second transmission gear is installed on the servo motor to engage with the first transmission gear to form a reducer. To ensure the appropriate speed during the welding process.

Further, two bosses are machined on the first transmission gear for installing the ion flame detector.

Further, the fixing nut is used to be fixed on the worktable and is easy to disassemble; the grooves are processed on the support of the rotary worktable and the buckles are installed, which can facilitate the disassembly of the product after welding; The copper twins are used to install the card, which is convenient for heat dissipation during the welding process.

The present invention adopts another technical scheme: a welding method for rotary argon arc welding of small-diameter thin-walled elbows, characterized in that the welding method comprises the following steps: selection of welding materials, cutting and groove processing, assembly before welding, Pre-welding debugging, test piece welding and testing, formal welding, post-welding heat preservation, and penetration testing; the specific steps are as follows:

The first step, welding material selection;

Use HGH3044 nickel-based superalloy welding wire with a diameter of 1.2, and use argon with a purity of 99.99% as the shielding gas;

The second step, blanking and groove processing;

The surface of the thin-walled elbow is processed with a pipe beveling machine, and the bevel angle is 60°-90° without blunt edges; the remaining oil on the bevel and surrounding surfaces is cleaned with acetone;

The third step is to assemble before welding;

The thin-walled elbow is sleeved on the electrode core column, and a joint gap of 0.5mm-1mm is required to be reserved;

The fourth step, debugging before welding;

Fix the welding torch at the position of the welding torch clamping mechanism of the welding torch holder, and adjust the X, Y, Z, R axes of the welding torch holder, and adjust the tungsten electrode of the welding torch to be just above the welding seam surface (2 -3) mm; in order to balance the heat input of the two workpieces of unequal thickness, the offset distance between the tungsten electrode and the place to be welded is S=(0.5-1) mm, and the switch of the DC power supply is turned on, and the current knob on the DC power supply is adjusted. To change the speed of the servo motor, adjust to the appropriate speed;

The fifth step, test piece welding and testing;

Place the two groups of test pieces processed before welding on the rotary table, turn on the torch switch and foot switch, and perform continuous welding for one week at the adjusted appropriate speed and current; the process parameters are as follows: as shown in Figure 9 , start the arc in the (a-b) interval, continuously weld for one week, and extinguish the arc in the (b-c) interval. In order to balance the heat input of the circumferential weld and ensure the consistency of the penetration depth of the circumferential weld, the automatic pulse argon arc welding process is adopted. The welding current of the 5th zone is 95%I, 97%I, 98%I, 93%I respectively, the welding time of the 2nd, 3rd, 4th and 5th zone is 3t, 2t, 4t, 2t, and the ventilation is still maintained after the arc is extinguished. (5-7) seconds;

The two groups of welded specimens were evaluated for the process, and the tensile test and the metallographic structure were tested respectively. The tensile strength of the tensile test was required to be no less than 540MPa. The crystals of the weld zone and the heat-affected zone were observed under an optical microscope. For grain size and penetration, the grain size of the weld zone should not be lower than grade 4, the grain size of the heat affected zone should not be lower than grade 5, and the penetration depth should not be less than 1mm.

The sixth step, formal welding;

If the tensile strength and metallographic structure of the test piece meet the requirements, the welding of the official product can be carried out, otherwise, continue to adjust the welding torch position, welding speed and welding current;

The seventh step, heat preservation after welding;

After one week of continuous welding, quickly remove the ion flame detector from the workbench, put it in a special thermal insulation cotton to keep warm to room temperature, and then take it out;

The eighth step is penetration testing;

Penetration testing and coloring inspection are carried out on the surface of the weld to observe whether there are cracks on the surface of the weld. If there are cracks, pick them out in time.

The beneficial effects of the present invention are:

(1) In the present invention, in order to balance the heat input in the welding process of two workpieces of unequal thickness, the tungsten electrode is offset from the position to be welded by a distance S=(0.5-1) mm. The manual argon arc welding is improved to continuous pulse argon arc welding, the circumferential weld is decomposed into five zones, the welding current and welding time of different zones are set, and the welding heat input of the whole circumference weld is balanced, which solves the problem of manual argon arc welding. Defects such as hot cracks, coarse grains, and inconsistent penetration of welds that appear in the method;

(2) The present invention provides a small diameter elbow welding device with a cantilever beam structure, which can realize rotary argon arc welding of this type of structure, and the welding device is small in size, light in weight, and easy to assemble and disassemble. The welding device subtly realizes the continuous rotary argon arc welding of the cantilever beam structure, the operation process is simple and efficient, and the manufacturing cost is low, and it is suitable as an easy-to-operate, low-cost and high-efficiency rotary argon arc welding device for the cantilever beam structure;

(3) The present invention produces a test piece (tensile test test piece, grain size test test piece) that simulates the joint of a formal product, and determines the tensile strength, grain size and melting point that meet the requirements of product use through experiments. The deep detection value can be used as a reference for the process evaluation of non-standard structures of small diameter thin-walled elbows and bars of the same diameter.

Description of drawings

FIG. 1 is a schematic structural diagram of the welding device of the present invention.

FIG. 2 is a schematic diagram of a welding torch fixing frame of the welding device of the present invention.

3 is a schematic front view of the rotary table of the welding device of the present invention.

4 is a schematic view of the reverse side of the rotary table of the welding device of the present invention.

FIG. 5 is a schematic diagram of welding of the ion flame detector of the present invention.

6 is a schematic diagram of a DC power supply of the welding device of the present invention.

FIG. 7 is a schematic diagram of the welding test piece of the present invention.

FIG. 8 is a flow chart of the welding method of the present invention.

FIG. 9 is a schematic diagram of the welding path and the welding seam partition of the present invention.

FIG. 10 is the effect diagram of the ion flame detector of the present invention after welding.

The marks in the figure are as follows: 1. Welding torch holder; 2. Rotary table; 4. Welding table; 11. X-axis adjustment clamp; 12. Y-axis adjustment clamp; 13, Z-axis adjustment clamp; 14, welding torch Clamping mechanism; 15. Z-axis support frame; 16. Y-axis support frame, 17. X-axis support frame, 18. R-axis adjustment clamp, 21. Worktable support; 22. Servo motor; 23. First transmission gear ; 24, the second transmission gear; 25, fixed nut; 26, boss; 27, buckle; 28, copper twins, 31, DC power supply, 32 power supply line;

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, it should be noted that, for the convenience of description, the drawings only show some but not all structures related to the present invention.

As shown in Figures 1-9, the present invention adopts the following technical solutions: a welding device for rotary argon arc welding of small diameter and thin-walled elbows, comprising: a welding torch holder 1, a rotary table 2, a DC power supply 31 and a welding work Table 4 is characterized in that: the welding torch holder 1, the rotary table 2, and the DC power source 31 are respectively placed on the welding table 4, wherein the DC power source 31 is connected to the servo motor 22 on the rotary table 2 for supplying the servo motor 22. The power supply drives the gear to rotate, and the welding torch holder 1 is used to fix the welding torch and adjust the position of the welding torch to ensure that the welding torch is located above the rotary table 2 .

Further, the welding torch fixing frame includes an X-axis adjustment clamp 11, a Y-axis adjustment clamp 12, a Z-axis adjustment clamp 13, an R-axis adjustment clamp 18, and an X-axis support frame 17 (there is a circle of X-axis in FIG. 2 . The gear is used to adjust the nut that moves in the X-axis direction, and the nut is screwed by hand to drive the X-axis to move by the gear engagement), the Y-axis support frame 16, the Z-axis support frame 15 and the welding gun clamping mechanism 14, which can realize welding gun clamping and Adjustment of the X, Y, Z, R axis directions; the Z axis support frame 15 is fixed on the welding table 4, the Z axis adjustment clamp 13 is sleeved on the Z axis support frame 15, and the Z axis support frame 15 is vertically connected to the R axis, The R-axis adjustment clamp 18 is sleeved on the R-axis, the R-axis is vertically connected to the X-axis support frame 17, the X-axis adjustment clamp 11 is sleeved on the X-axis support frame 17, and the X-axis support frame 17 is vertically connected to the Y-axis support frame 16. The Y-axis adjusting clamp 12 is sleeved on the Y-axis support frame 16, the Y-axis support frame 16 is connected to the welding torch clamping mechanism 14, and the welding torch clamping mechanism 14 is connected to the welding gun.

Further, the rotary table includes a table bracket 21, a servo motor 22, a first transmission gear 23, a second transmission gear 24, a fixing nut 25, a boss 26, a buckle 27 and a copper twin 28; the table bracket 21 passes through the The fixing nut 25 is tightened on the welding table 4, the servo motor 22 is installed on the table bracket 21, the second transmission gear 24 is tightened and fixed with the servo motor 22, the first transmission gear 23 is located above the second transmission gear 24, the boss 26 Located on the side of the first transmission gear 23 , the buckle 27 is directly above the workbench bracket 21 , and the red copper twin 28 is located between the buckle 26 and the workbench bracket 21 .

Further, the DC power supply 31 is connected to the foot switch 33 through the power supply line 32 . The DC power supply is equipped with a foot switch to control the power on and off of the motor during the welding process, which is convenient for the welder to operate.

Further, a second transmission gear is installed on the servo motor to engage with the first transmission gear to form a reducer. To ensure the appropriate speed during the welding process.

Further, two bosses are machined on the first transmission gear for installing the ion flame detector.

Further, the fixing nut is used to be fixed on the worktable and is easy to disassemble; the grooves are processed on the support of the rotary worktable and the buckles are installed, which can facilitate the disassembly of the product after welding; The copper twins are used to install the card, which is convenient for heat dissipation during the welding process.

The present invention adopts another technical scheme: a welding method for rotary argon arc welding of small-diameter thin-walled elbows, characterized in that the welding method comprises the following steps: selection of welding materials, cutting and groove processing, assembly before welding, Pre-welding debugging, test piece welding and testing, formal welding, post-welding heat preservation, and penetration testing; the specific steps are as follows:

The first step, welding material selection;

HGH3044 nickel-based superalloy welding wire with a diameter of 1.2 is selected, and argon gas with a purity of 99.99% is selected as the shielding gas.

The second step, blanking and groove processing;

The surface of the thin-walled elbow is processed with a pipe beveling machine, and the bevel angle is 60°-90° without blunt edges; the remaining oil stains on the bevel and surrounding surfaces are cleaned with acetone.

The third step is to assemble before welding;

Sleeve the thin-walled elbow on the electrode stem, and reserve (0.5-1)mm joint clearance.

The fourth step, debugging before welding;

Fix the welding torch at the position of the welding torch clamping mechanism of the welding torch holder, and adjust the X, Y, Z, R axes of the welding torch holder, and adjust the tungsten electrode of the welding torch to be just above the welding seam surface (2 -3) mm; in order to balance the heat input of the two workpieces of unequal thickness, the offset distance between the tungsten electrode and the place to be welded is S=(0.5-1) mm, and the switch of the DC power supply is turned on, and the current knob on the DC power supply is adjusted. To change the speed of the servo motor, adjust to the appropriate speed;

The fifth step, test piece welding and testing;

Place the two groups of test pieces processed before welding (as shown in Figure 7) on the rotary table respectively, turn on the welding torch switch and foot switch, and perform continuous welding for one week at the adjusted appropriate speed and current; process parameter requirements As follows: As shown in Figure 9, the arc is started in the (a-b) section, the welding is continued for one week, and the arc is extinguished in the (b-c) section. Using the automatic pulse argon arc welding process, the welding current of the first zone is I, the welding time is t, and the welding current of the second, 3, 4, and 5 zones is set by the ratio of 95%, 97%, 98%, 93% , the welding time of the 2nd, 3rd, 4th and 5th zones is 3t, 2t, 4t and 2t. Maintain ventilation (5-7) seconds after arc extinguishing;

The two groups of welded specimens were evaluated for the process, and the tensile test and the metallographic structure were tested respectively. The tensile strength of the tensile test was required to be no less than 540MPa. The crystals of the weld zone and the heat-affected zone were observed under an optical microscope. For grain size and penetration, the grain size of the weld zone should not be lower than grade 4, the grain size of the heat affected zone should not be lower than grade 5, and the penetration depth should not be less than 1mm.

The sixth step, formal welding;

If the tensile strength, metallographic structure and penetration detection of the test piece meet the requirements, the welding of the formal product can be carried out, otherwise, continue to adjust the welding torch position, welding speed and welding current.

The seventh step, heat preservation after welding;

After one week of continuous welding, quickly remove the ion flame detector from the workbench, put it in a special thermal insulation cotton to keep warm to room temperature, and then take it out.

The eighth step is penetration testing;

Penetration testing and coloring inspection are carried out on the surface of the weld to observe whether there are cracks on the surface of the weld. If there are cracks, pick them out in time.

The innovative points of the welding method of the present invention:

(1) In order to verify whether the welding parameters of the welding device can ensure the welding quality of the official product, it is necessary to make test pieces for process evaluation. The welded joint of the small diameter thin-walled elbow (Φ11.5×0.75) and the electrode core column (Φ12) is a non-standard joint, and there is no relevant process evaluation standard reference. The invention produces a test piece (tensile test test piece, grain size test test piece) simulating the joint of a formal product, and determines the welding seam quality standard that meets the product use requirements through tests, that is, the tensile strength of the welding test piece The test requires that the tensile strength is not less than 540MPa, and the grain size of the weld zone is not less than grade 4, the grain size of the heat affected zone is not less than grade 5, and the welding penetration depth is not less than 1mm;

(2) In order to balance the heat input of two parts with different thicknesses, the electrode core column obtains more heat during the welding process to make it balance with the part lost by heat conduction. Set at (0.5-1)mm;

(3) In order to balance the heat input of the circumferential weld to ensure the consistency of the penetration depth of the circumferential weld, the welding method of the present invention adopts the process method of automatic pulse argon arc welding, and divides the circumferential weld into 5 zones, the first zone The welding current is I, the welding time is t, the welding current of the 2nd, 3rd, 4th, and 5th zones is 95%I, 97%I, 98%I, 93%I, respectively, and the 2nd, 3rd, 4th, and 5th zones are welded The time is 3t, 2t, 4t, 2t.

Before the formal welding, put the ion flame detector on the corresponding position on the rotary table and fasten it with nuts. After the DC power supply is energized, adjust the parameters of the DC power supply to the appropriate welding speed. Fix the welding torch on the welding torch holder, and adjust the knob on the welding torch holder to adjust the welding torch to the proper welding position. Manually control the arc starting switch of the welding torch, and control the rotation of the ion flame detector through the foot switch. After one week of welding, release the arc starting switch of the welding torch and release the foot switch. Unscrew the nut on the rotary table and remove the ion flame detector from the table. The invention is used for continuously welding the elbow of the ion flame detector and the junction box part for one week. The outer circle of the electrode core column of the junction box component and the inner circle of the elbow are tightly fitted to form a butt joint, and the two are welded as a whole by manual argon arc welding.

The welding device includes a welding torch holder, a rotating worktable, a regulated power supply, and a foot switch, wherein the welding torch holder is used to fix the position of the welding torch, the rotating worktable is used to realize the continuous rotation of the ion flame detector, and the regulated power supply is used to fix the position of the welding torch. Provide current to the motor, and the foot switch is used to control the power on and off of the motor. The invention realizes the continuous rotary argon arc welding of the ion flame detector, improves the appearance of the argon arc welding seam forming, and ensures the reliability of the welding seam quality.

The beneficial effects of the present invention are as follows: the present invention balances the heat input in the welding process of two workpieces of unequal thickness, offsets the tungsten electrode from the position to be welded to the thick workpiece by a certain distance, and improves manual argon arc welding to continuous Pulse argon arc welding, decomposes the circumferential weld into five zones, sets the welding current and welding time in different zones, balances the welding heat input of the whole circumferential weld, and avoids weld hot cracks and crystallites that occur in the manual argon arc welding process. Coarse grains, inconsistent penetration and other defects, and at the same time, the production of welding equipment to achieve continuous rotary argon arc welding improves the appearance of argon arc welding seam formation, thereby ensuring the reliability of weld quality. The invention can realize the rotary argon arc welding of the small diameter thin-walled elbow and the same diameter bar, and the welding device is small in size, light in weight, and convenient for loading and unloading.

Note that the above are only preferred embodiments of the present invention and applied technical principles. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and can also include more other equivalent embodiments without departing from the concept of the present invention. The scope is determined by the scope of the appended claims.

Claims (9)

1. A welding device for rotary argon arc welding of a small-caliber thin-wall elbow comprises: welder mount, swivel work head, DC power supply and weldment work platform, its characterized in that: the welding gun fixing frame, the rotary workbench and the direct-current power supply are respectively arranged on the welding workbench, wherein the direct-current power supply is connected with the servo motor on the rotary workbench and used for supplying power to the servo motor to drive the gear to rotate, and the welding gun fixing frame is used for fixing the welding gun and adjusting the position of the welding gun to ensure that the welding gun is positioned above the rotary workbench.

2. The welding device for the rotary argon arc welding of the small-caliber thin-wall elbow pipe according to claim 1, wherein: the welding gun fixing frame comprises an X-axis adjusting clamp, a Y-axis adjusting clamp, a Z-axis adjusting clamp, an R-axis adjusting clamp, an X-axis support frame, a Y-axis support frame, a Z-axis support frame and a welding gun clamping mechanism, and welding gun clamping and X, Y, Z, R-axis direction adjustment can be realized; the Z-axis support frame is fixed on the welding workbench, the Z-axis adjusting clamp is sleeved on the Z-axis support frame, the Z-axis support frame is vertically connected with an R axis, the R-axis adjusting clamp is sleeved on an R axis, the R axis is vertically connected with an X-axis support frame, the X-axis adjusting clamp is sleeved on the X-axis support frame, the X-axis support frame is vertically connected with a Y-axis support frame, the Y-axis adjusting clamp is sleeved on the Y-axis support frame, the Y-axis support frame is connected with a welding gun clamping mechanism, and the welding gun clamping mechanism is connected with a welding gun.

3. The welding device for the rotary argon arc welding of the small-caliber thin-wall elbow pipe according to claim 1, wherein: the rotary workbench comprises a workbench bracket, a servo motor, a first transmission gear, a second transmission gear, a fixing nut, a boss, a buckle and a red copper cell; the workbench support is screwed on the welding workbench through a fixing nut, the servo motor is installed on the workbench support, the second transmission gear is screwed and fixed with the servo motor, the first transmission gear is located above the second transmission gear, the boss is located on the side face of the first transmission gear and is buckled right above the workbench support, and the red copper cell tire is located between the buckle and the workbench support.

4. The welding device for the rotary argon arc welding of the small-caliber thin-wall elbow pipe according to claim 1, wherein: the direct current power supply is connected with the foot switch through a power supply line.

5. The welding device for the rotating argon arc welding of the small-caliber thin-wall elbow according to claim 3, wherein: and a second transmission gear is arranged on the servo motor and meshed with the first transmission gear to form a speed reducer.

6. The welding device for the rotating argon arc welding of the small-caliber thin-wall elbow according to claim 3, wherein: 2 bosses are processed on the first transmission gear and used for installing the ion flame detector.

7. The welding method of the rotating argon arc welding of the small-caliber thin-wall elbow pipe according to claim 1, characterized by comprising the following steps of: the welding method comprises the following steps: selecting welding materials, blanking, processing grooves, assembling before welding, debugging before welding, welding and detecting a test piece, formally welding, preserving heat after welding and detecting penetration; the method comprises the following specific steps:

firstly, selecting welding materials;

selecting an HGH3044 nickel-based high-temperature alloy welding wire with the diameter of 1.2, and selecting argon with the purity of 99.99% as protective gas;

secondly, blanking and beveling;

processing the surface of the thin-wall bent pipe by adopting a pipeline beveling machine, wherein the bevel angle is 60-90 degrees and no truncated edge exists; cleaning residual oil stains on the groove and the peripheral surface by using acetone;

thirdly, assembling before welding;

sleeving the thin-wall bent pipe on the electrode stem, and reserving a joint gap of 0.5-1 mm; and fixing 2 points of circumferential symmetric argon arc welding at the butt joint of the groove bottoms;

fourthly, debugging before welding;

fixing a welding gun at a welding gun clamping mechanism of a welding gun fixing frame, adjusting an X, Y, Z, R shaft of the welding gun fixing frame, adjusting a tungsten electrode of the welding gun to be right above a position to be welded, wherein the distance between the tungsten electrode and the surface of a welding seam is 2-3mm, and in order to balance heat input quantity of two workpieces with different thicknesses, the offset distance S between the tungsten electrode and the position to be welded is 0.5-1mm, switching on a switch of a direct-current power supply, and adjusting a current knob on the direct-current power supply to change the rotating speed of a servo motor to an appropriate rotating speed;

Fifthly, welding and detecting a test piece;

placing two groups of test pieces processed before welding on a rotary worktable respectively, switching on a welding gun switch and a foot switch, and continuously welding for a circle at the adjusted proper rotating speed and current; the technological parameters are as follows: starting arc in the interval a-b, continuously welding for a circle, and extinguishing arc in the interval b-c; adopting an automatic pulse argon arc welding process, wherein the welding current of the 1 st area is I, the welding time is t, the welding currents of the 2 nd, 3 rd, 4 th and 5 th areas are 95% I, 97% I, 98% I and 93% I, and the welding times of the 2 nd, 3 rd, 4 th and 5 th areas are 3t, 2t, 4t and 2 t; the ventilation is kept for 5-7 seconds after the arc is extinguished;

the two groups of welded test pieces are subjected to process evaluation, and respectively subjected to a tensile test and metallographic structure detection, wherein the tensile test requires that the tensile strength is not lower than 540MPa, the grain sizes and the fusion depths of a welding seam area and a heat affected zone are observed under an optical microscope, the grain size of the welding seam area is not lower than 4 grade, the grain size of the heat affected zone is not lower than 5 grade, and the fusion depth is not smaller than 1 mm;

sixthly, formally welding;

if the tensile strength and metallographic structure detection of the test piece meet the requirements, welding formal products according to the process parameters of the fifth step, and otherwise, continuously adjusting the position of a welding gun, the welding speed and the welding current;

Seventhly, preserving heat after welding;

after one week of continuous welding, the ion flame detector is quickly taken down from the workbench, and is placed into special heat-insulating cotton for heat preservation to room temperature and then taken out;

eighthly, detecting infiltration;

and carrying out permeation detection and coloring inspection on the surface of the welding seam, observing whether cracks exist on the surface of the welding seam, and timely picking out the cracks if the cracks exist.

8. The welding method of the rotating argon arc welding of the small-caliber thin-wall elbow pipe according to claim 7, wherein in order to balance the heat input amount of two workpieces with different thicknesses, the offset distance S between the tungsten electrode and the position to be welded is 0.5-1 mm.

9. The welding method of the rotating argon arc welding for the small-caliber thin-wall bent pipe according to claim 7, wherein in order to balance the heat input of the circumferential weld joint and ensure the penetration consistency of the circumferential weld joint, the welding method adopts an automatic pulse argon arc welding process, the circumferential weld joint is divided into 5 zones, the welding current of the 1 st zone is I, the welding time is t, the welding currents of the 2 nd, 3 rd, 4 th and 5 th zones are respectively 95% I, 97% I, 98% I and 93% I, and the welding time of the 2 nd, 3 th, 4 th and 5 th zones is 3t, 2t, 4t and 2 t.

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