Method for undercutting high-alloyed welds of non-oriented silicon steel

Abstract

The application discloses a high-alloy-content edge digging method for a welded joint of non-oriented silicon steel, wherein the total content of silicon and aluminum of the non-oriented silicon steel is 3.5-5%, and the thickness d of the non-oriented silicon steel before cold rolling is 1.8-2.4 mm; the laser welding method is adopted for welding, and after welding, the non-oriented silicon steel is sent to an edge digging position; an electric shearing machine is used to dig the edge of an unsatisfied area of the welded joint, the shape of the dug edge is arc-shaped, the length of the dug edge is 10-20 cm, the maximum depth of the dug edge is 3-5 cm, and the shearing speed v satisfies 2 cm / s<=v<=5 cm / s. The edge cracking problem of the dug edge in the rolling process is greatly improved, the strip breakage caused by the edge cracking is avoided, and batch production of high-grade non-oriented steel with a silicon-aluminum alloy content of 3.5-5% on a UCMW cold continuous rolling mill is ensured.

Description

Technical Field

[0001] This invention relates to the field of edge treatment technology for silicon steel welds, and specifically to a method for trimming the edges of high-alloy non-oriented silicon steel welds. Background Technology

[0002] High-grade non-oriented silicon steel is mainly used in the manufacture of large and medium-sized motors and generators. With the implementation and promotion of the "dual carbon" policy, the new energy vehicle industry is developing rapidly, and the market for steel used in new energy drive motors is growing daily. The market demand for high-grade non-oriented silicon steel (silicon-aluminum content of 3.5% or higher) is strong. Improving the production efficiency of non-oriented silicon steel with a silicon-aluminum content of 3.5% or higher and reducing its cost per ton of steel are of great significance. Currently, the industry mainly produces non-oriented silicon steel with a silicon-aluminum content of 3.5% or higher using reversible rolling mills, which have low production efficiency and high cost. Meanwhile, the UCMW cold continuous rolling mill, which has high production efficiency and low cost, does not have the capacity for mass production of this type of steel.

[0003] Chinese patent application CN202022728865.3 discloses "An adjustable edge-cutting device for weld seam depth", which belongs to the field of welding equipment technology. It mainly solves the technical problem that the edge-cutting depth of existing welding machines is fixed and cannot flexibly match the edge-cutting depth on both sides of the weld seam according to the different alloy content of the strip steel.

[0004] For the production of non-oriented silicon steel with a total silicon-aluminum content of 3.5-5%, a crescent-shaped mechanical edge trimming shear is used to trim the edges of the weld to remove areas of insufficient weld metal. However, existing mechanical edge trimming shears cause stress concentration at the trimming interface; the higher the alloy content, the more pronounced the stress concentration. Welds in non-oriented silicon steel with a silicon-aluminum content of 3.5-5% are highly susceptible to edge cracking during rolling, leading to strip breakage. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of the above-mentioned technologies by providing a method for trimming welds of high-alloy non-oriented silicon steel produced on a UCMW continuous rolling mill.

[0006] To achieve the above objectives, the present invention relates to a method for trimming the weld seam of high alloy content non-oriented silicon steel. The total silicon and aluminum content of the non-oriented silicon steel is 3.5-5%, and the thickness d of the non-oriented silicon steel before cold rolling is 1.8-2.4 mm. Laser welding is used for welding. After welding, the weld seam is sent to the trimming area, and the unfilled area of ​​the weld seam is trimmed manually using an electric punch shear. The trimming shape is arc-shaped, the trimming length (along the running direction of the steel strip) is 10-20 cm, the maximum trimming depth (along the width direction of the steel strip) is 3-5 cm, and the trimming speed v satisfies 2 cm / s ≤ v ≤ 5 cm / s.

[0007] The reason this invention controls the shearing length (along the steel strip running direction) to be 10-20cm and the maximum shearing depth (in the steel strip width direction) to be 3-5cm is that a smoother shearing curve is more conducive to stress release. If the shearing depth is <3cm and the shearing length is <10cm, the weld tracking system cannot locate the weld position. The shearing speed v is controlled at 2-5cm / s. This is mainly because if the shearing speed is too fast, it is not conducive to stress release on the sheared surface, while if the shearing speed is too slow, it will increase the wear of the shear blade.

[0008] Furthermore, the gap D of the electric punching shear satisfies 0.1×d≤D≤0.1×(d+1). The electric punching shear gap D is adjusted according to the thickness of the base material. If the punching shear gap is too small, the tear surface will be too large and the burrs will be too large. If the punching shear gap is too large, it will increase the deformation of the grains on the shear surface, which is not conducive to rolling.

[0009] Furthermore, a suitable shearing speed is selected based on the different alloy contents of the base material. As the alloy content of the base material increases, the shearing speed decreases accordingly. The aluminum content of the non-oriented silicon steel is denoted as 'a', and the silicon content as 'b'. When the silicon-aluminum content is 3.5% ≤ a + b ≤ 4%, the shearing speed v satisfies 4 cm / s ≤ v ≤ 5 cm / s; when the silicon-aluminum content is 4% ≤ a + b ≤ 4.5%, the shearing speed v satisfies 3 cm / s ≤ v ≤ 4 cm / s; and when the silicon-aluminum content is 4.5% ≤ a + b ≤ 5%, the shearing speed v satisfies 2 cm / s ≤ v ≤ 3 cm / s.

[0010] Furthermore, the number of no-load reciprocating cycles of the electric punch shear is 1200-1500 times / min. The higher the no-load reciprocating frequency, the more beneficial the stress release is to the vibration generated during the shearing process.

[0011] Furthermore, the electric punch shears are oil-cooled when not in use to ensure that the hardness of the shearing punch is maintained during continuous operation.

[0012] Furthermore, the edges are heated using a handheld flamethrower. The appropriate heating temperature T is selected based on the alloy content: when the silicon-aluminum content is 3.5% ≤ a + b ≤ 4%, the heating temperature T satisfies 400℃ ≤ T ≤ 450℃; when it is 4% ≤ a + b ≤ 4.5%, the heating temperature T satisfies 450℃ ≤ T ≤ 500℃; and when it is 4.5% ≤ a + b ≤ 5%, the heating temperature T satisfies 500℃ ≤ T ≤ 550℃, with a fluctuation range of ±5℃. The control of the heating temperature is primarily because higher temperatures accelerate the recrystallization of grains in the heated zone, resulting in a greater difference in grain size between the grains and the base material, making edge cracks and band breakage more likely during rolling; conversely, lower heating temperatures make it more difficult to release stress during shearing.

[0013] Furthermore, the thickness of the non-oriented silicon steel before cold rolling is 1.8mm ≤ d ≤ 2mm, and the heating time t satisfies 30s ≤ t ≤ 40s; the thickness of the non-oriented silicon steel before cold rolling is 2mm ≤ d ≤ 2.2mm, and the heating time t satisfies 40s ≤ t ≤ 50s; the thickness of the non-oriented silicon steel before cold rolling is 2.2mm ≤ d ≤ 2.4mm, and the heating time t satisfies 50s ≤ t ≤ 60s; the fluctuation range is ±2s. The control of the heating time is because as the plate thickness increases, the total number of grains at the cut edge increases, and the energy required for grain growth also increases; if the heating time is too short, the grains cannot fully recover and recrystallize, and stress cannot be effectively eliminated.

[0014] Furthermore, after heating, the heated area is air-cooled using compressed air to prevent the rubber roller from being burned by the high temperature.

[0015] Compared with the prior art, the present invention has the following advantages: the edge-cutting method of the present invention greatly improves the problem of edge cracking during the rolling process, avoids strip breakage caused by edge cracking, and ensures that the UCMW cold continuous rolling mill can mass-produce high-grade non-oriented steel with silicon-aluminum alloy content of 3.5-5%. Attached Figure Description

[0016] Figure 1 Diagram showing the fracture zone caused by edge cracking resulting from traditional crescent-shaped edge cutting and shearing of weld seams;

[0017] Figure 2 This is a diagram showing that the electric punch shear weld seam has no edge cracks after edge cutting and rolling.

[0018] Figure 3 This is a diagram of the substrate before edge trimming.

[0019] Figure 4 This is a diagram of mechanical edge trimming;

[0020] Figure 5 This is a diagram of the electric punching shear cutting edge of the present invention. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific embodiments to facilitate a clearer understanding of the present invention, but these embodiments do not constitute a limitation on the present invention.

[0022]

[0023] like Figure 1 The image shown illustrates the fracture zone caused by edge cracking during traditional crescent-shaped edge cutting and shearing weld seams. Figure 2 This invention presents a diagram showing the absence of edge cracks after edge trimming and rolling of an electro-shear weld. Metallographic observation was conducted to examine the microstructure changes and burr size caused by different processing methods. The sample was mounted and observed along the parallel direction of the shear cross-section to examine the microstructure and burr condition. Figure 3 , Figure 4 , Figure 5The deformation zone of mechanical cutting is larger, and the matrix near the cutting edge is subjected to greater compression and deformation, while the matrix structure of electric punching and shearing cutting is not affected.

Claims

1. A method for trimming the edges of high-alloy non-oriented silicon steel welds, characterized in that: The total silicon and aluminum content of the non-oriented silicon steel is 3.5-5%, and the thickness d of the non-oriented silicon steel before cold rolling is 1.8-2.4 mm. Welding is carried out by laser welding. After welding, the steel is sent to the edge trimming area. The edge of the weld is trimmed by electric punch shear. The trimming shape is arc-shaped, the trimming length is 10-20 cm, the maximum trimming depth is 3-5 cm, and the trimming speed v satisfies 2 cm / s ≤ v ≤ 5 cm / s. The gap D of the electric punch shear satisfies 0.1×d≤D≤0.1×(d+1); The aluminum content of the non-oriented silicon steel is denoted as a, and the silicon content is denoted as b. When the silicon-aluminum content is 3.5%≤a+b≤4%, the shearing speed v satisfies 4cm / s≤v≤5cm / s; when the silicon-aluminum content is 4%≤a+b≤4.5%, the shearing speed v satisfies 3cm / s≤v≤4cm / s; when the silicon-aluminum content is 4.5%≤a+b≤5%, the shearing speed v satisfies 2cm / s≤v≤3cm / s. The electric punch shear has an unloaded reciprocating cycle count of 1200~1500 times / min; After edge trimming, the steel undergoes heat treatment. When the silicon-aluminum content is 3.5%≤a+b≤4%, the heating temperature T satisfies 400℃≤T≤450℃; when it is 4%≤a+b≤4.5%, the heating temperature T satisfies 450℃≤T≤500℃; when it is 4.5%≤a+b≤5%, the heating temperature T satisfies 500℃≤T≤550℃. Before cold rolling, the thickness of the non-oriented silicon steel is 1.8mm≤d≤2mm, and the heating time t satisfies 30s≤t≤40s; before cold rolling, the thickness of the non-oriented silicon steel is 2mm≤d≤2.2mm, and the heating time t satisfies 40s≤t≤50s; before cold rolling, the thickness of the non-oriented silicon steel is 2.2mm≤d≤2.4mm, and the heating time t satisfies 50s≤t≤60s. The control of heating temperature is mainly because the higher the heating temperature, the faster the recrystallization of the grains in the heating zone will be. The greater the difference between the grain size and the base material, the easier it is to form edge cracks and break the strip during the rolling process. The lower the heating temperature, the more difficult it is to release the stress during the shearing process.

2. The method for trimming the edge of high-alloy non-oriented silicon steel welds according to claim 1, characterized in that: The electric punch shear is oil-cooled when not in use.

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