Method for welding inner cover cylinder of cover type annealing furnace

Abstract

The invention discloses a cover type annealing furnace inner cover barrel welding method which comprises the following steps: A, pressing high-strength stainless steel for manufacturing an inner cover barrel into a corrugated shape through a plate pressing machine, and adjusting the width stroke of the plate pressing machine in the pressing process to enable the wave troughs of corrugated steel plates to be located at the edge; b, a corrugated steel plate is cut to be made into a plurality of sections of round barrels, the edges of the round barrels are all concave trough circles, the barrels are spliced in pairs, and all joints are located at the troughs; c, trapezoidal grooves are machined in the outer sides of the end faces where the wave troughs of every two adjacent corrugated steel plates are welded, and the seam gap between the two corrugated steel plates is smaller than 1 mm; and D, after the inner side and the outer side are welded, the surplus height of a welding seam on the outer side ranges from 1.5 mm to 2.5 mm, and the welding seam on the inner side is ground to be flat. The invention can solve the problem that the welding seam of the inner cover of the existing cover-type annealing furnace is blocked with the heating cover on the outer side after being deformed and swelled in use, and the welding seam is often cracked.

Description

Technical Field

[0001] The invention relates to the technical field of steel material heat treatment equipment manufacturing, in particular to a bell-type annealing furnace barrel corrugation welding method for steel material heat treatment equipment. Background Art

[0002] As the key equipment in the production of hood-type annealing furnace, the inner hood is welded with multiple sections of corrugated circular cylinders. The firmness and stability of the welds have always been a problem that affects the service life of the inner hood. The height of the inner hood of the cold-rolled carbon steel hood-type annealing furnace is generally 6 meters to 7 meters. The circular cylinder of the inner hood is made of high-strength stainless steel. Due to the limitation of the width of stainless steel, the circular cylinder of the inner hood can only be welded by multiple sections of cylinders. In order to increase the lightness and heat-absorbing surface of the inner hood, most of the inner hood cylinders are corrugated. During the use of the inner hood of the hood-type annealing furnace, when heating, the inner hood will be repeatedly baked by the flame of the burning nozzle of the outer heating hood. The inner hood transfers the heat generated by the burning of the heating hood to the steel coil inside the inner hood to achieve the purpose of annealing the steel coil; when cooling, the inner hood will be flushed with water, and the heat of the steel coil inside will be taken away through the inner hood to achieve the purpose of cooling the steel coil. The inner cover cylinder is repeatedly baked and heat transferred, which makes the welds on the cylinder very easy to deform and bulge after thermal expansion and contraction, and get stuck with the outer heating cover, causing cracks at the welds, shortening the service life of the inner cover and posing a great challenge to its safe operation. Summary of the invention

[0003] The problem to be solved by the present invention is to provide a method for welding the inner cover cylinder of a bell-type annealing furnace, so as to solve the problem that the weld of the inner cover of the existing bell-type annealing furnace is blocked by the outer heating cover after deformation and bulging during use, and the weld often cracks.

[0004] In order to solve the above problems, the technical scheme of the present invention is: the inner cover cylinder welding method of the hood annealing furnace comprises the following steps: A, the high-strength stainless steel for making the inner cover cylinder is pressed into a corrugated shape by a plate press, and the width stroke of the plate press is adjusted during the pressing process so that the trough of the corrugated steel plate is at the edge; B, the corrugated steel plate is made into a plurality of circular cylinders with fixed lengths, the edges of the circular cylinders are all concave trough circles, and the cylinders are spliced ​​together in pairs so that each joint is at the trough; C, a trapezoidal groove is processed on the outer side of the end surface of the trough welding of two adjacent corrugated steel plates, and the joint gap between the two corrugated steel plates is less than 1mm; D, after welding the inside and outside, the outer side weld excess height is in the range of 1.5mm~2.5mm, and the inner side weld is polished and smooth; wherein the excess height is the amount by which the maximum height of the weld is higher than the end surface of the corrugated steel plate.

[0005] In the above technical solution, a more specific solution may be: in step C, a trapezoidal groove is also processed on the inner side of the end surface of the trough weld of two adjacent corrugated steel plates, wherein the end surface area of ​​the outer trapezoidal groove is larger than the end surface area of ​​the inner trapezoidal groove.

[0006] Further: after step D, the method also includes step E: cleaning welding slag and spatter after welding, and inspecting the weld for flaws.

[0007] Further: Step E also includes step F: after the welding of the multiple sections of the inner cover cylinder is completed, the inner cover is subjected to overall vibration aging treatment to eliminate the residual stress of the inner cover cylinder.

[0008] Further: In step C, the trapezoidal angle of the trapezoidal groove is ±45°.

[0009] Further: In step D, the outer weld reinforcement is in the range of 1.5 mm to 2.0 mm.

[0010] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art: The method for welding the inner cover cylinder of the hood-type annealing furnace controls the pressing width stroke when manufacturing the cylinder so that the edge of each corrugated steel plate is at the trough, ensuring that every two corrugated steel plates are welded at the trough, so as to improve the strength during thermal expansion and reduce the thermal expansion; trapezoidal grooves are opened on the outer sides of the two corrugated steel plates, the outer groove is large and the inner groove is small, so that the outer side can withstand greater heat changes and reduce the deformation of the outer side of the weld. The outer weld excess height is within the range of 1.5mm~2.5mm, and the inner weld is polished and smoothed, which can enhance the weld strength and reduce the weld cracking phenomenon, while reducing the deformation and expansion at the weld, and preventing the inner weld of the inner cover from protruding and causing mutual blocking and scratching with the outer heating cover. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a top view of the inner cover phase corrugated cylinder of an embodiment of the present invention; Figure 2 is a cross-sectional view of the weld of the inner cover phase corrugated cylinder of an embodiment of the present invention; Figure 3 yes Figure 2 A magnified image of point A; Markings in the figure: crest 1 of the inner cover corrugated cylinder, trough 2 of the inner cover corrugated cylinder, weld 3 of two adjacent corrugated steel plates of the inner cover at the trough, inner cover corrugated cylinder 4, weld 5. DETAILED DESCRIPTION

[0012] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings: like Figures 1 to 3 The method for welding the inner cover cylinder of the hood-type annealing furnace comprises the following steps: A. The 310S high-strength stainless steel with a width of 1500mm for the inner cover cylinder is pressed into a corrugated shape by a press machine. During the pressing process, the width stroke of the press machine is adjusted by 100mm so that the trough of the corrugated steel plate is at the edge; 310S stainless steel material is rolled and welded into a corrugated cylinder. The corrugation can improve the strength of the inner cover and the heat transfer contact area.

[0013] B. The corrugated steel plate is cut into multiple circular cylinders with concave wave valleys at the edges. The cylinders are spliced ​​together in pairs so that each joint is at the wave valley.

[0014] C. A trapezoidal groove is processed on the outer side of the end surface of the trough weld of two adjacent corrugated steel plates, and a trapezoidal groove is also processed on the inner side of the end surface of the trough weld of two adjacent corrugated steel plates, wherein the end surface area of ​​the outer trapezoidal groove is larger than the end surface area of ​​the inner trapezoidal groove, wherein the trapezoidal angle a of the trapezoidal groove is ±45°, and the joint gap between the two corrugated steel plates is <1mm.

[0015] D. After welding the inner and outer sides, the outer weld excess height h is between 1.5 mm and 2.0 mm, and the inner weld is ground and smooth; the excess height is the amount by which the maximum height of the weld is higher than the end face of the corrugated steel plate. In other embodiments, depending on the size of the bell annealing furnace, the outer weld excess height can also be between 1.5 mm and 2.5 mm.

[0016] E. Clean the welding slag and spatter after welding, inspect the weld to ensure it meets the national weld grade II standard.

[0017] F. After the welding of the multiple sections of the inner cover is completed, the inner cover is subjected to overall vibration aging treatment to eliminate the residual stress of the inner cover cylinder.

[0018] The method controls the pressing width stroke when manufacturing the cylinder so that the edge of each corrugated steel plate is at the trough, ensuring that every two corrugated steel plates are welded at the trough, so as to improve the strength during thermal expansion and reduce the thermal expansion; trapezoidal grooves are opened on the outer sides of the two corrugated steel plates, with a larger outer groove and a smaller inner groove, so that the outer side can withstand greater heat changes and reduce the deformation of the outer side of the weld; the outer side weld residual height is within the range of 1.5mm-2.5mm, and the inner side weld is smoothed and polished, so as to enhance the weld strength and reduce the weld cracking phenomenon, and reduce the deformation and expansion at the weld, and prevent the inner side weld of the inner cover from protruding and causing mutual obstruction and scratching with the outer heating cover, and reduce the number of times the inner cover weld cracks during thermal expansion and contraction, and extend the service life of the inner cover, which has a significant effect on reducing the cost of equipment use, ensures the stable operation of production and improves product quality, and has achieved very good economic benefits in practical applications.

Claims

1. A method for welding a cover cylinder in a cover-type annealing furnace, characterized in that The following steps are involved: A. Press the high-strength stainless steel used to make the inner cover cylinder into a corrugated shape through a press machine. During the pressing process, adjust the width of the press machine so that the trough of the corrugated steel plate is at the edge; B. The corrugated steel plate is made into multiple circular cylinders with concave troughs at the edges. The cylinders are spliced ​​together in pairs so that each joint is at the trough; C. A trapezoidal groove is processed on the outer side of the end surface of the trough welding of two adjacent corrugated steel plates, and the joint gap between the two corrugated steel plates is less than 1mm; D. After welding the inside and outside, the outer weld excess height is within the range of 1.5mm~2.5mm, and the inner weld is ground smooth; the excess height is the amount by which the maximum height of the weld is higher than the end face of the corrugated steel plate.

2. The method for welding the inner cover cylinder of a bell-type annealing furnace according to claim 1, characterized in that: In step C, a trapezoidal groove is also processed on the inner side of the end surface of the trough welding of two adjacent corrugated steel plates, wherein the end surface area of ​​the outer trapezoidal groove is larger than the end surface area of ​​the inner trapezoidal groove.

3. The method for welding the inner cover cylinder of a bell-type annealing furnace according to claim 2, characterized in that: The method further includes step E after step D: cleaning welding slag and spatter after welding, and inspecting the weld for flaws.

4. The method for welding the inner cover cylinder of a bell-type annealing furnace according to claim 3, characterized in that: Step E also includes step F: after the welding of the multiple sections of the inner cover cylinder is completed, the inner cover is subjected to overall vibration aging treatment to eliminate the residual stress of the inner cover cylinder.

5. The method for welding a bell-type annealing furnace inner bell-type annealing furnace according to any one of claims 1 to 4, characterized in that: In step C, the trapezoidal angle of the trapezoidal groove is ±45°.

6. The method for welding the inner cover cylinder of a bell-type annealing furnace according to claim 5, characterized in that: In step D, the outer weld reinforcement is in the range of 1.5 mm to 2.0 mm.

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