Method for preventing cracks from being generated at end part of cylinder section of tank body and production method of railway wagon tank body

Abstract

The invention discloses a method for preventing cracks from being generated at the end part of a cylinder section of a tank body and a production method of a railway wagon tank body. Comprising the following steps: 1) splicing two tank plates to obtain a spliced plate for forming a shell ring; wherein when the two tank plates are spliced, the plate edge staggered teeth are controlled to be not larger than 1.5 mm, the local staggered teeth are not larger than 2 mm, and the plate end staggered teeth are not larger than 1.5 mm; (2) rolling the jointed board to form the shape of a shell ring so as to obtain a shell ring prefabricated body; (3) longitudinal joints in the shell ring prefabricated body are welded, so that an initial shell ring is obtained; wherein the run-on plate and the run-off plate are respectively welded at two ends of the longitudinal seam; submerged-arc welding is adopted for welding, the welding speed is 28-30 m / h, the thickness of a welding flux is 25-35 mm, the deviation amount of a welding seam is not larger than 2 mm, the welding voltage is 35-40 V, and the welding current is 400-550 A; (4) the initial shell ring is subjected to roundness correction, and therefore the shell ring is obtained; wherein the run-on plate and the run-off plate are cut off after roundness correction is completed. According to the method, cracks can be basically prevented from being generated at the end of the cylinder section of the tank body.

Description

Technical Field

[0001] The present invention relates to a method for avoiding cracks at the ends of cylinder sections of a tank body and a production method for a tank body of a railway freight car. Background Art

[0002] The tank body of a railway freight car is a horizontal cylindrical container. During production, its main body is formed by 6 cylinder sections, and the cross-section of each cylinder section is circular. The welds of the tank body need to be verified for quality by radiographic inspection, and the welding quality of the longitudinal welds is particularly important. During the production process, cracks often appear at the ends of the cylinder sections, and the inspection results are unqualified, resulting in repeated re-welding and inspection, increasing the labor intensity and rework cost.

[0003] There is a literature report on a welding device and a welding method for low-temperature welding of large tank bodies. This welding method can preheat the workpiece before welding and keep the workpiece warm after welding, avoiding the sudden cooling of the workpiece in a low-temperature environment, solving the problems of cracks and brittle fracture caused by the severe shrinkage of welding materials, and improving the processing quality of low-temperature welding. Summary of the Invention

[0004] One object of the present invention is to provide a method for avoiding cracks at the ends of cylinder sections of a tank body, which can basically avoid cracks at the ends of the cylinder sections, improve the weld quality, and reduce the labor intensity and rework cost. Another object of the present invention is to provide a production method for a tank body of a railway freight car.

[0005] The object of the present invention is achieved by the following technical solutions.

[0006] The present invention provides a method for avoiding cracks at the ends of cylinder sections of a tank body, comprising the following steps:

[0007] 1) Splice two tank plates to obtain a spliced plate for forming a cylinder section; wherein, when splicing the two tank plates, control the edge misalignment of the plates to be not more than 1.5 mm and locally not more than 2 mm, and the end misalignment of the plates to be not more than 1.5 mm;

[0008] 2) Roll the spliced plate to form the shape of a cylinder section to obtain a cylinder section preform;

[0009] 3) Weld the longitudinal seam in the cylinder section preform to obtain an initial cylinder section; wherein, an arc starting plate and an arc ending plate are respectively welded at both ends of the longitudinal seam; submerged arc welding is used for welding, the welding speed is 28 - 30 m / h, the thickness of the welding flux is 25 - 35 mm, the deviation of the weld seam is not more than 2 mm, the welding voltage is 35 - 40 V, and the welding current is 400 - 550 A;

[0010] 4) Round the initial cylinder section to obtain the cylinder section; among which, cut off the arc starting plate and the arc ending plate after rounding. This is beneficial to avoid cracks at the ends of the cylinder section. This reduces labor intensity, reduces weld repair, and reduces the human and material costs of radiographic inspection.

[0011] In step 1), splicing two tank plates means putting the two tank plates together without welding first, and then welding the longitudinal seam after forming the cylinder section preform. In step 2), the central axis direction of the cylinder section preform obtained by plate rolling is consistent with the length direction of the longitudinal seam between the tank plates (i.e., consistent with the length direction of the splicing seam). There are two longitudinal seams in one cylinder section preform. In step 3), the welding speed is preferably 29 - 30 m / h. The welding flux can be of type 431 or type 101. The welding voltage is preferably 38 - 40 V, and the welding current is preferably 450 - 550 A. There shall be no defects such as cracks and pores on the weld surface. In step 4), after rounding, use a cutting disc to cut off the arc starting plate and the arc ending plate, and do not remove them forcefully to avoid forming end cracks. The cutting method can be those known in the art.

[0012] According to the method of the present invention, preferably, before welding, dry the welding flux at 220 - 280 °C for 1.5 - 3 h. Preferably, dry the welding flux at 250 - 260 °C for 1.5 - 2 h.

[0013] According to the method of the present invention, preferably, before welding, use the method of the trolley running empty to align, and control the deviation of the welding nozzle of the welding torch from the longitudinal seam to be welded to be no more than 1 mm. Using the method of the trolley running empty to align means aligning by running the welding machine empty without welding.

[0014] According to the method of the present invention, preferably, closely attach the arc starting plate and the arc ending plate to the parts to be welded of the longitudinal seam of the cylinder section preform respectively, so that the arc starting plate and the arc ending plate are flush with the outside of the cylinder section preform respectively, the butt gap is no more than 0.5 mm, and the arc starting plate and the arc ending plate are flush with the outer surface of the tank plate respectively, and the misalignment is no more than 0.5 mm.

[0015] According to the method of the present invention, preferably, weld the butt joints between the arc starting plate and the arc ending plate and the cylinder section preform respectively, and control the weld length to be no less than 100 mm.

[0016] According to the method of the present invention, preferably, the effective welding lengths of the starting end of the arc starting plate and the ending end of the arc ending plate are respectively no less than 100 mm.

[0017] According to the method of the present invention, preferably, the effective welding lengths of the starting end of the arc starting plate and the ending end of the arc ending plate are respectively no less than 80 mm.

[0018] According to the method of the present invention, preferably, the method further includes the following step: performing a flaw detection experiment on the obtained cylinder section.

[0019] On the other hand, the present invention also provides a production method for a railway freight car tank body, including the following steps:

[0020] 1) Splice two tank plates to obtain a spliced plate for forming a cylinder section; wherein, when splicing the two tank plates, control the edge misalignment of the plates to be no more than 1.5 mm and locally no more than 2 mm, and the end misalignment of the plates to be no more than 1.5 mm;

[0021] 2) Roll the spliced plate to form the shape of a cylinder section to obtain a cylinder section preform;

[0022] 3) Weld the longitudinal seam in the cylinder section preform to obtain an initial cylinder section;

[0023] Wherein, an arc starting plate and an arc ending plate are respectively welded at both ends of the longitudinal seam; submerged arc welding is used for welding, the welding speed is 28 - 30 m / h, the thickness of the welding flux is 25 - 35 mm, the deviation of the weld seam is no more than 2 mm, the welding voltage is 35 - 40 V, and the welding current is 400 - 550 A;

[0024] 4) Round the initial cylinder section to obtain a cylinder section; wherein, the arc starting plate and the arc ending plate are cut off after the rounding is completed;

[0025] 5) Repeat steps 1) to 4) to obtain multiple other cylinder sections;

[0026] 6) Assemble all the obtained cylinder sections to form the shape of a tank body to obtain a tank body to be welded;

[0027] 7) Weld the tank body to be welded through an inner ring welding process and an outer ring welding process to obtain the main body of the railway freight car tank body. In this way, cracks at the ends of the cylinder sections can be avoided, which is beneficial to forming a tank body with qualified quality.

[0028] In step 5), generally, all the cylinder sections are six cylinder sections, so that the formed tank body can meet the use requirements.

[0029] In step 7), welding the tank body to be welded through an inner ring welding process and an outer ring welding process means welding between adjacent cylinder sections in the tank body to be welded. The inner ring welding process and the outer ring welding process can refer to those known in the art and will not be elaborated here.

[0030] According to the production method of the present invention, preferably, it further includes: performing a flaw detection experiment on each obtained cylinder section respectively. In the present invention, an X-ray flaw detector can be used for the flaw detection experiment. There are no special restrictions on the manufacturer and model of the X-ray flaw detector.

[0031] The method for avoiding cracks at the ends of the cylindrical sections of the tank body of the present invention can basically avoid the generation of cracks at the ends of the cylindrical sections, improve the weld quality, and reduce the labor intensity and repair cost. This method is applicable to the control of crack defects at the ends of tank products such as railway tank cars and tank containers. Specific embodiments

[0032] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0033] Example 1

[0034] This embodiment provides a method for avoiding cracks at the ends of the cylindrical sections of the tank body, including the following steps:

[0035] 1) Splice two tank plates to obtain a spliced plate for forming a cylindrical section; wherein, when splicing the two tank plates, control the edge misalignment of the plates to be no more than 1.5 mm and locally no more than 2 mm, and the end misalignment of the plates to be no more than 1.5 mm;

[0036] 2) Roll the spliced plate to form the shape of a cylindrical section, thereby obtaining a prefabricated cylindrical section;

[0037] 3) Weld the longitudinal seam in the prefabricated cylindrical section to obtain an initial cylindrical section;

[0038] Among them, submerged arc welding is used for welding.

[0039] Before welding, dry the welding flux at 250 °C for 1.5 h.

[0040] Before welding, align by means of the empty running of the trolley (that is, without welding, the welding machine runs empty), and control the deviation of the welding nozzle of the welding torch from the longitudinal seam to be welded to be no more than 1 mm.

[0041] Weld the starting plate and the ending plate at both ends of the longitudinal seam. Specifically, closely fit the starting plate and the ending plate to the parts to be welded of the longitudinal seam of the prefabricated cylindrical section respectively, so that the starting plate and the ending plate are flush with the outside of the prefabricated cylindrical section respectively, the butt gap is no more than 0.5 mm, and the starting plate and the ending plate are flush with the outer surface of the tank plate respectively, and the misalignment amount is no more than 0.5 mm; weld the butt joints between the starting plate, the ending plate and the prefabricated cylindrical section respectively, control the weld length to be no less than 100 mm, and the effective welding lengths of the starting end of the starting plate and the ending end of the ending plate are no less than 80 mm respectively;

[0042] During welding, the welding speed is 30 m / h, the thickness of the welding flux is 25 - 35 mm, the deviation of the weld seam is not more than 2 mm, the welding voltage is 35 - 40 V, and the welding current is 450 - 500 A. It is necessary to control that there are no defects such as cracks and pores on the surface of the weld seam. After welding, observe the surface quality of the weld seam. Note that the arc extinguishing pit part must be trimmed to be smoothly transitioned with the surrounding part, and V-shaped grooves and narrow grooves cannot be formed.

[0043] 4) Round the initial cylinder section to obtain the cylinder section; among them, after rounding is completed, the arc striking plate and the arc extinguishing plate are cut off with a cutting disc and cannot be forcibly removed. Perform flaw detection experiments on the obtained cylinder section. The result of the flaw detection experiment is that there are no cracks at the ends of the cylinder section. The quality is qualified.

[0044] Example 2

[0045] This embodiment provides a production method for a railway freight car tank body, including the following steps:

[0046] 1) Splice two tank plates to obtain a spliced plate for forming a cylinder section; among them, when splicing the two tank plates, control the edge misalignment of the plates to be not more than 1.5 mm and locally not more than 2 mm, and the end misalignment of the plates to be not more than 1.5 mm;

[0047] 2) Roll the spliced plate to form the shape of a cylinder section to obtain a cylinder section preform;

[0048] 3) Weld the longitudinal seam in the cylinder section preform to obtain an initial cylinder section;

[0049] Among them, submerged arc welding is used for welding.

[0050] Before welding, dry the welding flux at 250 °C for 1.5 h.

[0051] Before welding, use the method of the trolley running empty (that is, without welding and the welding machine running empty) to align, and control the deviation of the welding nozzle of the welding torch from the longitudinal seam to be welded to be not more than 1 mm.

[0052] Closely fit the arc striking plate and the arc extinguishing plate to the parts to be welded of the longitudinal seam of the cylinder section preform respectively, so that the arc striking plate and the arc extinguishing plate are flush with the outside of the cylinder section preform respectively, the butt joint gap is not more than 0.5 mm, and the arc striking plate and the arc extinguishing plate are flush with the outer surface of the tank plate respectively, and the misalignment amount is not more than 0.5 mm; weld the butt joint parts between the arc striking plate, the arc extinguishing plate and the cylinder section preform respectively, control the weld seam length to be not less than 100 mm, and the effective welding lengths of the starting end of the arc striking plate and the ending end of the arc extinguishing plate are not less than 80 mm respectively;

[0053] During welding, the welding speed is 30 m / h, the thickness of the welding flux is 25 - 35 mm, the deviation of the weld seam is not more than 2 mm, the welding voltage is 35 - 40 V, and the welding current is 450 - 500 A;

[0054] 4) calibrating the initial cylinder segment to obtain the cylinder segment; wherein the arc starting plate and the arc ending plate are removed after the calibration is completed;

[0055] 5) Repeat steps 1) to 4) to obtain another five cylinder sections; each cylinder section obtained is subjected to a flaw detection test. The flaw detection test results show that there are no cracks, no defects, and the quality is qualified.

[0056] 6) Assembling the six obtained cylinder sections to form the shape of the tank body, thereby obtaining the tank body to be welded;

[0057] 7) The tank body to be welded is welded through the inner ring welding process and the outer ring welding process to obtain the main body of the railway freight car tank body. The main body is a cylindrical structure.

[0058] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A method for avoiding cracks at the ends of the cylindrical sections of a tank body, characterized in that, It includes the following steps: 1) Join two tank plates to obtain a spliced plate for forming a cylinder section. When joining the two tank plates, control the edge misalignment of the plates to be no more than 1.5 mm and locally no more than 2 mm, and the end misalignment of the plates to be no more than 1.5 mm. 2) Roll the spliced plate to form the shape of a cylinder section to obtain a prefabricated cylinder section. 3) Weld the longitudinal seam in the prefabricated cylinder section to obtain an initial cylinder section. Wherein, an arc starting plate and an arc ending plate are welded at both ends of the longitudinal seam respectively. Submerged arc welding is used, the welding speed is 28 - 30 m / h, the thickness of the welding flux is 25 - 35 mm, the deviation of the weld seam is no more than 2 mm, the welding voltage is 35 - 40 V, and the welding current is 400 - 550 A. 4) Round the initial cylinder section to obtain a cylinder section. Wherein, the arc starting plate and the arc ending plate are cut off after the rounding is completed.

2. The method according to claim 1, wherein Before welding, dry the welding flux at 220 - 280 °C for 1.5 - 3 h.

3. The method according to claim 1, wherein Before welding, align by means of the trolley running empty, and control the deviation of the welding nozzle of the welding torch from the longitudinal seam to be welded to be no more than 1 mm.

4. The method according to claim 1, wherein Closely fit the arc starting plate and the arc ending plate to the parts to be welded of the longitudinal seam of the prefabricated cylinder section respectively, so that the arc starting plate and the arc ending plate are flush with the outside of the prefabricated cylinder section respectively, the butt gap is no more than 0.5 mm, and the arc starting plate and the arc ending plate are flush with the outer surface of the tank plate respectively, and the misalignment is no more than 0.5 mm.

5. The method according to claim 4, wherein Weld the butt joints between the arc starting plate and the arc ending plate and the prefabricated cylinder section respectively, and control the weld length to be no less than 100 mm.

6. The method according to claim 4, wherein The effective welding lengths of the starting end of the arc starting plate and the ending end of the arc ending plate are respectively no less than 100 mm.

7. The method according to claim 6, characterized in that, The effective welding lengths of the starting end of the arc starting plate and the ending end of the arc ending plate are respectively no less than 80 mm.

8. The method according to claim 1, characterized in that It also includes the following steps: Conduct a flaw detection test on the obtained cylinder section.

9. A production method of a railway freight car tank body, characterized in that, It includes the following steps: 1) Join two tank plates to obtain a spliced plate for forming a cylinder section. When joining the two tank plates, control the edge misalignment of the plates to be no more than 1.5 mm and locally no more than 2 mm, and the end misalignment of the plates to be no more than 1.5 mm. 2) Roll the spliced plate to form the shape of a cylinder section to obtain a prefabricated cylinder section. 3) Weld the longitudinal seam in the prefabricated cylinder section to obtain an initial cylinder section. Wherein, an arc starting plate and an arc ending plate are welded at both ends of the longitudinal seam respectively. Submerged arc welding is used, the welding speed is 28 - 30 m / h, the thickness of the welding flux is 25 - 35 mm, the deviation of the weld seam is no more than 2 mm, the welding voltage is 35 - 40 V, and the welding current is 400 - 550 A. 4) Round the initial cylinder section to obtain a cylinder section. Wherein, the arc starting plate and the arc ending plate are cut off after the rounding is completed. 5) Repeat steps 1) to 4) to obtain multiple other cylinder sections. 6) Join all the obtained cylinder sections to form the shape of a tank body to obtain a tank body to be welded. 7) Weld the tank body to be welded through an inner ring welding process and an outer ring welding process to obtain the main body of the railway freight car tank body.

10. The production method according to claim 9, characterized in that, It also includes: Conduct a flaw detection test on each obtained cylinder section respectively.