CN110711921A

CN110711921A - Welding process method for aluminum alloy medium plate of railway vehicle

Info

Publication number: CN110711921A
Application number: CN201911075833.3A
Authority: CN
Inventors: 何岩; 李业雄; 李万君; 宋帅帅
Original assignee: CRRC Changchun Railway Vehicles Co Ltd
Current assignee: CRRC Changchun Railway Vehicles Co Ltd
Priority date: 2019-11-06
Filing date: 2019-11-06
Publication date: 2020-01-21

Abstract

A rail vehicle aluminum alloy medium plate welding process method, the welding site environment temperature is more than or equal to 18 ℃, the humidity is less than or equal to 60%, 4 layers of 6 welding layers are adopted, the single layer is not broken, the aluminum alloy plate with a 50-degree V-shaped groove is welded, and the welding area of the base metal is cleaned up within the range of 25mm before welding; the truncated edge of the groove is 1mm, the starting end of the root gap is 4-5 mm, the ending part is 6-7 mm, the group is preheated by 100 ℃ with the permanent backing plate, 5 points are evenly distributed and positioned at intervals of 50mm, and each section is 30-50 mm; carrying out linear reciprocating arc motion, after welding, measuring the temperature of a welding seam by using a temperature measuring instrument, continuing to perform cover surface welding if the temperature is not higher than 100 ℃, and cooling to below 100 ℃ if the temperature is higher than 100 ℃ and then welding; two capping surfaces are adopted in capping welding, the welding current is 220-240A, and the voltage is 24-26V. The invention solves the problem of larger welding deformation caused by overlarge heat input of single-layer single-pass welding, and the auxiliary tool ensures that the angle of the welding gun is always fixed and the moving body of a welder is stable when the welder carries out welding. Two joints can be reduced by one welding line in the production process, the qualified rate of radiographic inspection after welding is improved, and the labor intensity of welders is reduced.

Description

Welding process method for aluminum alloy medium plate of railway vehicle

Technical Field

The invention belongs to the technical field of welding of aluminum alloy medium plates of railway vehicles, and particularly relates to a welding process method for a traction part at the front end of a vehicle chassis.

Background

The length of a welding seam of a traction part at the front end of the chassis of the Beijing-Zhang high-speed rail car body is 1700mm, the thickness of an aluminum alloy plate is 60mm, and a groove of 60 degrees is formed. The problems of arc stopping joints, welding gun angle deviation and the like are easily generated in the welding process, so that the quality is reduced, and the RT flaw detection qualification rate after welding is influenced. The welding needs a larger welding deposition rate to complete the welding due to the thickness of the base metal and the angle of the groove, and the welding deformation after welding is larger.

Disclosure of Invention

The invention aims to solve the technical problems of arc stopping joint problem and welding gun angle deviation in the welding process caused by overlong weld joint size, thereby providing a long weld joint welding process method for aluminum alloy medium and thick plates, which reduces welding deformation and ensures the qualification rate of RT flaw detection after welding.

In order to achieve the aim, the invention provides a process method for welding a medium and thick aluminum alloy plate of a railway vehicle, which is characterized by comprising the following steps of:

1. the temperature of the welding site environment is more than or equal to 18 ℃, the humidity is less than or equal to 60%, 4 layers of 6 welding layers are adopted, the arc is not broken in a single layer, the aluminum alloy plate with a 50-degree V-shaped groove is welded, and the welding area of the base metal is cleaned within the range of 25mm before welding;

2. the truncated edge of the groove is 1mm, the starting end of the root gap is 4-5 mm, the ending part is 6-7 mm, the group is preheated to 100 ℃ by adding the permanent backing plate, the welding path is evenly distributed with positioning points at intervals of 50mm, and each section is 30-50 mm;

3. linear reciprocating arc welding is adopted, the second layer of the filling layer is filled twice, after welding is finished, a temperature measuring instrument is used for measuring the temperature of a welding seam, if the temperature is not higher than 100 ℃, cover surface welding is continuously carried out, and if the temperature is higher than 100 ℃, the welding seam needs to be cooled to be lower than 100 ℃ and then welded.

And 2, performing section welding by taking the positioning points as references, wherein arc-closing points of the section welding are closed on the positioning points.

The straight reciprocating arc welding is arc short arc welding by adopting a crescent swing back method or a sawtooth method, so that an electric arc is burnt at the inner side of the groove, the filling metal covers the edge of the groove and then is carried out forwards, and the undercut defect is avoided.

And the cover surface is pressed on two thirds of the first welding process during the second welding process of the cover surface welding.

Before the step 3 is carried out, erecting a welding auxiliary tool, taking a groove of the aluminum alloy profile of the vehicle body as a transverse movement positioning reference of the semi-automatic auxiliary welding tool, matching 6 sliding wheels of the auxiliary tool with the groove to serve as a walking guide rail, and fixing a welding gun while supporting an arm of a welder with the tool during welding.

The welding method is applied to the welding production of the aluminum alloy car body of the railway car, and solves the problem of large welding deformation caused by overlarge heat input of single-layer single-pass welding. When welding, the auxiliary tool ensures that the angle of the welding gun is always fixed, and the welder moves the body stably. Two joints can be reduced by one welding line in the production process, the qualified rate of radiographic inspection after welding is improved, and the labor intensity of welders is reduced.

Drawings

FIG. 1 is a schematic view of the welding direction of the present invention;

FIG. 2 is a schematic diagram of parameters of plate thickness, groove angle, groove truncated edge, and groove clearance;

FIG. 3 is a schematic view of a weld bead distribution;

FIG. 4 is a pictorial representation of a welded article made by the method of the present invention.

Detailed Description

Referring to fig. 1-3, a particular welding embodiment of the present invention includes the following steps:

1. the temperature of the field environment is more than or equal to 18 ℃, the humidity is less than or equal to 60%, the support bracket is moved by welding, 4 layers of 6 welding, single-layer arc-free and 50-degree V-shaped groove aluminum alloy plates are adopted, and after acid cleaning is carried out on the base metal, a stainless steel bowl brush machine is used for polishing the front and back surfaces of the periphery of the welding seam within the range of 25mm to remove an oxidation film;

2. adding a permanent base plate to the welding line pair, and polishing the base plate groove by using a stainless steel bowl brushing machine to remove an oxidation film;

3. the bevel angle a is 50 degrees, the thickness b of the truncated edge is 1mm, the starting end c of the root gap of the bevel is 4-5 mm, the ending part is 6-7 mm, and t1 and t2 represent that the thickness of the plate is 12 mm;

4. when in tack welding, the backing plate and the plate are tightly aligned and can not have a gap, a baking gun preheats the periphery of the tack welding by 100 ℃, and the measurement and confirmation are carried out by a temperature measuring gun;

5. evenly distributing and positioning 5 points from the beginning to the end of a 2-meter long weld bead, wherein the interval of each positioning point is 50mm, performing section welding by taking the positioning points as a reference, and a section welding arc-closing point is closed on the positioning points to prevent welding deformation, wherein the section welding length of each section is 30-50 mm;

6. erecting a welding auxiliary tool, taking a groove of an aluminum alloy profile of a vehicle body as a transverse movement positioning reference of a semi-automatic auxiliary welding tool, matching 6 sliding wheels of the auxiliary tool with the groove to serve as a walking guide rail, and fixing a welding gun while supporting the arm of a welder by the tool during welding (the gun support can rotate front and back and left and right, so that the operation and adjustment during welding are convenient);

7. adopting multilayer multi-pass welding with 4 layers and 6 passes (1-6 passes in figure 3), preheating the periphery of a welding seam by a baking gun before welding, and measuring and confirming by a temperature measuring gun; the backing welding adopts large-current small-voltage welding, the current is 230-250A, the voltage is 22-24V, and short-arc welding is adopted. The welding gun keeps 85 degrees with the welding direction, and the welding pool is convenient to observe. The penetration force of welding arc is strong, and the weld seam is formed narrowly and deeply. Observing that the arc of the molten pool spreads and hits two sides of the groove to move forwards, holding the welding gun by the right hand, and moving the body of a welder to drive the auxiliary tool to move along the welding direction to finish welding operation;

8. and moving the trolley back to the initial section of the welding line, and cleaning is not needed between layers. The first layer is filled with 230-250A and 24-26V voltage, and arc is transferred by drawing saw teeth left and right. The welding arc is pressed down, the welding gun is slightly stopped for about 0.5 second at the left and right slope edges, and the welding arc passes through the middle. And the welding gun is held by the right hand, and the body of a welder moves to drive the auxiliary tool to move along the welding direction, so that the welding operation is completed.

9. And moving the trolley back to the initial section of the welding line, and cleaning is not needed between layers. The second layer of the filling layer is filled twice, the current and voltage are the same as those of the first layer, and arc welding is carried out by adopting a crescent swing-back method. And welding one welding gun at each side of the groove, and paying attention to the fact that the groove edge is damaged when the welding gun angle is inclined to the filling of the side. And the body of the welder is held by the right hand to move so as to drive the auxiliary tool to move along the welding direction to complete the welding operation. And measuring the temperature of the welding seam by using a thermodetector after welding, continuing to perform cover surface welding if the temperature is not higher than 100 ℃, and cooling to below 100 ℃ if the temperature is higher than 100 ℃ and then welding.

10. And moving the trolley back to the initial section of the welding line, and cleaning is not needed between layers. Two cover surfaces are adopted in cover surface welding, the current is 220-240A, the voltage is 24-26V, short-arc welding is needed to avoid undercut defects, and undercut caused by unstable electric arc is avoided. Arc is transported by adopting a crescent swing back method or a sawtooth method, so that the arc is burnt at the inner side of the groove, and the filling metal covers the edge of the groove to move forwards. And the body of the welder is held by the right hand to move so as to drive the auxiliary tool to move along the welding direction to complete the welding operation. And moving the trolley back to the initial section of the welding line, and cleaning is not needed between layers. It should be noted that the second welding of the cap surface is pressed on two thirds of the first welding, the welding specification current 210-.

Referring to fig. 4, a welding method according to the present invention: when welding, the auxiliary tool ensures that the angle of the welding gun is always fixed, the body of a welder is stable to move, no joint exists after one 2M long welding line is welded, and two joints can be reduced by one welding line in the production process; the angle of the welding gun is always kept consistent from the initial welding end to the final welding end, so that the internal fusion of the welding seam is ensured to be good, the qualified rate of the radiographic inspection after welding is improved, and the labor intensity of a welder is reduced.

Claims

1. A rail vehicle aluminum alloy medium plate welding process method is characterized by comprising the following steps:

(1) the temperature of the welding site environment is more than or equal to 18 ℃, the humidity is less than or equal to 60%, 4 layers of 6 welding layers are adopted, the arc is not broken in a single layer, the aluminum alloy plate with a 50-degree V-shaped groove is welded, and the welding area of the base metal is cleaned within the range of 25mm before welding;

(2) the truncated edge of the groove is 1mm, the starting end of the root gap is 4-5 mm, the ending part is 6-7 mm, the group is preheated to 100 ℃ by adding the permanent backing plate, the welding path is evenly distributed with positioning points at intervals of 50mm, and each section is 30-50 mm;

(3) linear reciprocating arc welding is adopted, the second layer of the filling layer is filled twice, after welding is finished, a temperature measuring instrument is used for measuring the temperature of a welding seam, if the temperature is not higher than 100 ℃, cover surface welding is continuously carried out, and if the temperature is higher than 100 ℃, the welding seam needs to be cooled to be lower than 100 ℃ and then welded.

2. The welding process method for the aluminum alloy medium plate of the railway vehicle as claimed in claim 1, wherein the welding process method comprises the following steps: and (2) performing section welding by taking the positioning point as a reference, wherein a section welding arc-ending point is arranged on the positioning point.

3. The welding process method for the aluminum alloy medium plate of the railway vehicle as claimed in claim 1, wherein the welding process method comprises the following steps: the straight reciprocating arc welding is arc short arc welding by adopting a crescent swing back method or a sawtooth method, so that an electric arc is burnt at the inner side of the groove, the filling metal covers the edge of the groove and then is carried out forwards, and the undercut defect is avoided.

4. The welding process method for the aluminum alloy medium plate of the railway vehicle as claimed in claim 1, wherein the welding process method comprises the following steps: and when the second welding of the cover surface welding is carried out, the cover surface is pressed on two thirds of the first welding.

5. The welding process method for the aluminum alloy medium plate of the railway vehicle as claimed in claim 1, wherein the welding process method comprises the following steps: before the step (3) is carried out, erecting a welding movable supporting bracket, using a groove of an aluminum alloy section of the vehicle body as a transverse movement positioning reference of the welding movable supporting bracket, matching a sliding wheel of the welding movable supporting bracket with the groove to serve as a walking guide rail, and fixing a welding gun while supporting an arm of a welder with the tool during welding.