A method for periodically varying the speed of feeding a core-spun yarn

Abstract

The application relates to a cored wire periodic gradual speed feeding method, which comprises the following steps: step S1, selecting a molten steel descending flow area according to the argon blowing hole position at the bottom of a ladle; and step S2, feeding the cored wire into the molten steel descending flow at a periodically changed feeding speed; and through adjustment of different feeding speeds, the cored wire is melted at different depths of a molten pool. Compared with the prior art, the application has the advantages of avoiding local over-high alloy element concentration, uniformly diffusing the alloy elements, reducing the reaction degree, improving the element yield, reducing the production cost and the like.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and in particular to a method for periodically and gradually increasing the speed of cored wire feeding. Background Technology

[0002] In the current steel metallurgical production process, it is usually necessary to add various alloying elements to the molten steel to adjust the composition of the molten steel and to modify the molten steel. Feeding cored wire into the molten steel can overcome the disadvantages of some alloying elements having low density, low melting point, strong affinity with oxygen in steel, making them difficult to add in the furnace or come into contact with slag, and causing secondary oxidation and burn-off, compared with the traditional method of adding alloying ingots. The main purposes of wire feeding are as follows: (1) To modify inclusions, eliminate the harm of high melting point hard inclusions, and improve casting performance. (2) To deoxidize and desulfurize, improve the cleanliness of steel, and improve product quality and performance. (3) To improve the fine-tuning composition of steel, ensure the element recovery rate during the wire feeding process, accurately control the composition of steel, and ensure composition stability.

[0003] In the prior art, Chinese Patent Publication No. CN110184415A discloses "A Wire Feeding Device and Method for Ladle Refining," which provides a wire feeding device and method for ladle refining, solving the problem of low alloy recovery rate caused by factors such as alloy wire passing through the slag layer, secondary oxidation, and low vapor pressure in the traditional wire feeding process. However, this invention does not solve the problem of excessively high local concentrations of alloy elements at the feeding point, which cannot dissolve and diffuse in time and are prone to overflow from the molten steel. Chinese Patent Publication No. CN201254586Y discloses "An Insertion-Type Wire Feeder," but this invention also leads to excessively high local concentrations of alloy elements at the feeding point, preventing the alloy elements from diffusing effectively. Chinese patent CN115466822A discloses a "feeding device and control method for spheroidizing treatment," which adjusts the feeding speed based on temperature differences to ensure that the melting point of the cored wire is near the bottom of the ladle at different temperatures. However, its drawback is that the local concentration of alloying elements is too high, preventing them from dissolving and diffusing quickly enough, leading to leakage from the molten steel, resulting in low alloying element recovery and increased costs. In summary, the existing technology suffers from problems such as excessively high local concentrations of alloying elements at the feeding point, a small dissolution and diffusion range, low alloying element recovery, and increased costs. Therefore, this invention provides a periodic, gradually varying speed feeding method for cored wire. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art and provide a method for periodically gradually increasing the speed of cored wire feeding.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] This invention discloses a method for periodically and gradually increasing the feeding speed of cored wire, comprising the following steps:

[0007] Step S1: Select the area of ​​the molten steel descending flow based on the location of the argon blowing hole at the bottom of the ladle;

[0008] Step S2: Feed the cored wire into the molten steel stream at a periodically varying feeding speed; by adjusting different feeding speeds, the cored wire is melted at different depths in the molten pool.

[0009] Furthermore, the positions of the argon blowing holes at the bottom of the ladle in step S1 include a double-hole centrally symmetrical argon blowing mode, a double-hole argon blowing mode with the line connecting the center at a certain angle, and a single-hole argon blowing mode.

[0010] Furthermore, when using the dual-hole central symmetric argon blowing mode, the cored wire is fed into the region of the molten steel descending flow generated at the position of the dual-hole central symmetry plane.

[0011] Furthermore, when using the double-hole argon blowing mode at a certain angle to the center line, the cored wire is fed into the molten steel downward flow region generated at the symmetrical position of the ladle center at the midpoint of the line connecting the two argon blowing ports.

[0012] Furthermore, when using the single-hole argon blowing mode, the cored wire is fed into the molten steel downflow region at the center symmetrical position of the argon blowing hole.

[0013] Furthermore, the wire feeding speed, cored wire melting time, and feeding depth mentioned in step S2 satisfy the following formula:

[0014]

[0015] Where V is the wire feeding speed, h is the feeding depth, and τ is the cored wire melting time.

[0016] Furthermore, the melting time τ of the cored wire satisfies the following formula in relation to the diameter d of the cored wire and the core thickness δ:

[0017] τ=1.015·δ(1-δ / d)·d 0.5 .

[0018] Furthermore, the range of the feeding depth includes the minimum allowable feeding depth to the maximum allowable feeding depth; wherein, the minimum allowable feeding depth is 0.2m from the surface of the molten steel, i.e., h min =0.2, the maximum allowable feeding depth is 0.2m from the bottom of the ladle, i.e., h max =H-0.2, where H is the depth of the molten pool.

[0019] Furthermore, the range of the wire feeding speed includes the minimum wire feeding speed to the maximum wire feeding speed; wherein, the maximum wire feeding speed V1 ≤ the maximum permissible wire feeding speed Vmax The maximum permissible feed rate is calculated based on the maximum permissible feed depth, and the minimum feed rate V2 ≥ minimum permissible feed rate V min The minimum allowable feed rate is calculated based on the minimum allowable feed depth.

[0020] The feeding speed, periodic function, minimum feeding speed, and maximum feeding speed satisfy the following formula:

[0021] Or V = (V1 - V2) * |f(t)| + V2

[0022] Where V is the wire feeding speed, V1 is the maximum wire feeding speed and V2 is the minimum wire feeding speed, and f(t) is a basic elementary periodic function.

[0023] Furthermore, the basic elementary periodic functions include sine wave functions, cosine wave functions, and sawtooth wave functions.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention adopts a periodic gradual speed feeding method, which can effectively dissolve the cored wire in different parts of the molten steel, avoid the problem of excessive local concentration of alloying elements, and make the alloying elements diffuse evenly, thereby reducing the degree of reaction, increasing the element yield, and reducing production costs.

[0026] (2) By adjusting different wire feeding speeds, the cored wire is melted at different depths in the molten pool, avoiding the violent reaction caused by excessively high element concentration in local locations, promoting uniform mixing of alloying elements in the molten steel, and suppressing the volatilization and burning loss of alloying elements by feeding the cored wire into the molten steel downflow, thereby improving the element recovery rate. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the periodically changing wire feeding state according to the present invention;

[0028] Figure 2 This is a schematic diagram of the feeding state when the periodically varying wire feeding speed of the present invention is at its maximum wire feeding speed;

[0029] Figure 3 This is a schematic diagram of the wire feeding state when the periodically varying wire feeding speed of the present invention is at its minimum wire feeding speed;

[0030] Figure 4 The diagram shows a vertical cross-section of the molten steel flow field and a horizontal distribution diagram of the argon blowing holes when using a dual-hole centrally symmetrical argon blowing method according to the present invention.

[0031] Figure 5The diagram shows the vertical cross-section of the molten steel flow field and the horizontal distribution of the argon blowing holes when the two holes are connected to the center line at a certain angle according to the present invention.

[0032] Figure 6 The diagram shows a vertical cross-section of the molten steel flow field and a horizontal distribution diagram of the argon blowing holes when using a single-hole argon blowing method according to the present invention.

[0033] Figure labels: 1 is cored wire, 2 is wire feeder body, 3 is wire outlet conduit, 4 is ladle, 5 is molten steel flow direction, 6 is argon blowing hole, 7 is wire feeding position when using double-hole center-symmetrical argon blowing, 8 is the angle θ between the two argon blowing holes and the center line, 9 is the wire feeding position when using double holes at a certain angle to the center line, 10 is the wire feeding position when using single-hole argon blowing. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0035] Example

[0036] This embodiment provides a method for periodically and gradually increasing the feeding speed of cored wire, such as... Figure 1 As shown, the method includes the following steps:

[0037] Step 1: Select the area of ​​the molten steel descending stream based on the location of the argon blowing hole at the bottom of the ladle.

[0038] Specifically, in actual production, argon blowing from the bottom of the ladle is used to make the composition and temperature of the molten steel more uniform, while removing non-metallic inclusions. Argon blowing utilizes the rising of argon bubbles to create a circulating flow of molten steel. Depending on the position and number of argon blowing holes at the bottom of the ladle, different flow fields of molten steel will be formed. When the wire feed position is in the rising stream of molten steel, the vapors of some alloying elements will quickly reach the surface of the molten steel along the rising flow, leading to severe volatilization of alloying elements and a reduced yield. When the wire feed position is in the descending stream of molten steel, the downward flow of molten steel will hinder the rise of alloying element vapors, allowing them more time to dissolve and diffuse in the molten steel, thereby improving the element yield and promoting uniform steel composition. This embodiment employs three argon blowing methods: a double-hole centrally symmetrical argon blowing mode, a double-hole argon blowing mode with the line connecting the center and the hole at a certain angle, and a single-hole argon blowing mode.

[0039] like Figure 4As shown, when using the dual-hole centrally symmetrical argon blowing mode, the reflux zones formed by the two blowing holes "collide" on the plane of symmetry, causing some of the agitation energy to cancel each other out, weakening the motion velocity, and thus forming a distinct downward flow stream near the centrally symmetrical plane. At this time, the cored wire can be fed into the downward flow stream in the molten steel on the dual-hole centrally symmetrical plane.

[0040] like Figure 5 As shown, when using the argon blowing mode with the two orifices at a certain angle to the center line, the two gas column regions merge into an upward flow with a wider cross-sectional area, which is beneficial to increasing the stirring kinetic energy. Then, a downward flow is generated at the symmetrical position of the ladle center at the midpoint of the line connecting the two argon blowing orifices. At this time, the cored wire can be fed into this downward flow.

[0041] like Figure 6 As shown, when using the single-hole argon blowing mode, a descending stream will form at a position symmetrical to the center of the argon blowing hole. At this time, a cored wire can be fed into the descending stream at the symmetrical position of the argon blowing hole. By feeding the cored wire into the descending stream of molten steel using different argon blowing modes, the upward overflow of alloy element vapors can be suppressed, and the alloy elements can diffuse to other areas of the molten steel along with the flow field, thereby improving the uniformity of the molten steel composition and increasing the element yield.

[0042] Step 2: Feed the cored wire into the molten steel downflow at a periodically varying feed rate. The feed rate is controlled within a certain range and continuously varied according to a periodic function, resulting in a gradual, periodic transition between fast and slow speeds. By adjusting different feed rates, the cored wire melts at different depths in the molten pool, avoiding excessively high element concentrations in localized areas that could lead to violent reactions. This promotes uniform mixing of alloying elements within the molten steel. By feeding the cored wire into the molten steel downflow, the volatilization and burn-off of alloying elements can be suppressed, thereby improving element recovery.

[0043] The wire feeding speed V is related to the core wire melting time τ and the feeding depth h. The shorter the core wire melting time and the deeper the feeding depth, the higher the maximum value of the wire feeding speed. Conversely, the longer the core wire melting time and the shallower the feeding depth, the smaller the minimum value of the wire feeding speed.

[0044] like Figure 2 and Figure 3 As shown, when using this embodiment for periodic gradual speed feeding, a maximum value V1 and a minimum value V2 need to be set to ensure that the cored wire is fed evenly to all parts of the ladle without touching the bottom of the ladle and without causing a large amount of alloying elements to overflow, volatilize, and burn off in the molten steel. When the cored wire is fed into the molten steel, the feeding depth is h, and its theoretical feeding speed V = feeding depth h / melting time τ. The theoretical feeding speed of the cored wire into the molten steel is shown in equation (1):

[0045]

[0046] In the formula: V is the wire feeding speed, in m / s; h is the cored wire feeding depth, in m; τ is the melting time, in s.

[0047] The melting time τ of the cored wire is mainly related to the diameter d of the cored wire and the thickness δ of the core sheath. The melting time of the cored wire is shown in equation (2):

[0048] τ=1.015·δ(1-δ / d)·d 0.5 (2)

[0049] In the formula: τ is the melting time of the cored wire, in seconds; d is the diameter of the cored wire, in mm; δ is the core thickness, in mm.

[0050] The cored wire feeding speed changes periodically with the increase of feeding time. The maximum allowable feeding depth of the cored wire is about 0.2m from the bottom of the ladle, i.e., h. max =H-0.2, where H is the depth of the molten pool. Substituting into equation (1), the corresponding maximum allowable wire feed speed is V. max Furthermore, to avoid the alloying elements from overflowing, volatilizing, or burning out due to insufficient dissolution caused by excessively shallow feeding speed, the minimum allowable feeding depth of the cored wire is 0.2m from the surface of the molten steel, i.e., h. min =0.2, substituting into equation (1), we can obtain the corresponding minimum feed linear velocity as V. min In actual wire feeding, the maximum feeding depth h1 ≤ h max The corresponding maximum feed line speed V1≤V max Minimum feed depth h2 ≥ h min The corresponding minimum feed line speed V2 ≥ V min The feeding speed based on the basic elementary periodic function f(t) can be given by equation (3) or equation (4).

[0051]

[0052] V=(V1-V2)·|f(t)|+V2 (4)

[0053] In the formula: t is the wire feeding time, with units of s; V1 is the maximum wire feeding speed, with units of m / s; V2 is the minimum wire feeding speed, with units of m / s; f(t) is a basic elementary periodic function of time t.

[0054] The periodically changing feed linear velocity function f(t) can be one of the following functions: sine wave function, cosine wave function, sawtooth wave function, etc., as shown in the following formula:

[0055] (1) Sine wave function:

[0056] f(t)=sin(ωt) (5)

[0057] (2) Cosine wave function:

[0058] f(t)=cos(ωt) (6)

[0059] (3) Sawtooth wave function:

[0060] f(t)=2(ft-[ft])-1 (7)

[0061] In the formula: t is time, with units of seconds; f(t) is the basic elementary periodic function of the feed line velocity, with units of m / s; ω is the angular frequency, ω = 2π / T, with units of seconds. -1 T is the period, with units of seconds (s); f is the frequency, f = 1 / T, with units of seconds (s). -1 [ft] represents the integer part of ft.

[0062] To verify the effectiveness of this embodiment, two different magnesium-cored wires were used to feed molten steel for testing.

[0063] Specifically, in the production of pipeline steel, at the end of RH refining, magnesium-core wire is fed into the molten steel to perform inclusion modification treatment. The wire feeding is carried out in two different ladles, as shown in Table 1.

[0064] The cored wire is fed into the molten steel through a wire feeder and a curved conduit. Two types of cored wire are used, as shown in Table 2. The melting time of cored wire 1 is about 1.19s, and the melting time of cored wire 2 is 0.88s.

[0065] Table 3 shows the process parameters for different embodiments. Comparative Examples 1 and 2 use a conventional constant wire feeding speed, while Test Examples 1 to 5 use the periodic gradual speed feeding method of this invention. In Comparative Examples 1 and 2, the molten steel surface fluctuates significantly during the feeding process, resulting in some splashing and the generation of a considerable amount of white smoke. In Test Examples 1 to 5, the cored wire is fed evenly to all parts of the ladle without touching the bottom and without causing a large amount of alloying elements to overflow, volatilize, or burn off in the molten steel; the feeding process is stable. Alloying elements diffuse evenly, and the recovery rate of Mg is significantly improved.

[0066] Table 1 Ladle Dimensions

[0067]

[0068] Table 2 Specifications of Cored Wire

[0069]

[0070] Table 3 Wire feeding process parameters

[0071]

[0072] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for periodically and gradually increasing the speed of cored wire feeding, characterized in that, Includes the following steps: Step S1: Select the area of ​​the molten steel descending flow based on the location of the argon blowing hole at the bottom of the ladle; Step S2: Feed the cored wire into the molten steel downflow at a periodically varying feeding speed; by adjusting different feeding speeds, the cored wire is melted at different depths in the molten pool; The wire feeding speed, cored wire melting time, and feeding depth mentioned in step S2 satisfy the following formula: in, V For wire feeding speed, h For feed depth, τ This refers to the melting time of the cored wire; The cored wire melting time τ With the diameter of the cored wire d and core thickness δ Satisfy the following formula: 。 2. The method for periodically and gradually increasing the speed of cored wire feeding according to claim 1, characterized in that, The positions of the argon blowing holes at the bottom of the ladle in step S1 include a double-hole centrally symmetrical argon blowing mode, a double-hole argon blowing mode with the line connecting the center to the center forming a certain angle, and a single-hole argon blowing mode.

3. The method for periodically and gradually increasing the speed of cored wire feeding according to claim 2, characterized in that, When using the dual-hole central symmetric argon blowing mode, the cored wire is fed into the region of the molten steel descending flow generated at the position of the dual-hole central symmetry plane.

4. The method for periodically and gradually increasing the speed of cored wire feeding according to claim 2, characterized in that, When using the double-hole argon blowing mode with the center line at a certain angle, the cored wire is fed into the molten steel downward flow region generated at the symmetrical position of the ladle center at the midpoint of the line connecting the two argon blowing ports.

5. The method for periodically and gradually increasing the speed of cored wire feeding according to claim 2, characterized in that, When using the single-hole argon blowing mode, the cored wire is fed into the molten steel descending flow region at a position symmetrical to the center of the argon blowing hole.

6. The method for periodically and gradually increasing the speed of cored wire feeding according to claim 1, characterized in that, The range of the feeding depth includes the minimum allowable feeding depth to the maximum allowable feeding depth; wherein, the minimum allowable feeding depth is 0.2m from the surface of the molten steel, i.e. h min =0.2, the maximum allowable feeding depth is 0.2m from the bottom of the ladle, that is h max = H -0.2, H This represents the depth of the molten pool.

7. The method for periodically and gradually increasing the speed of cored wire feeding according to claim 6, characterized in that, The range of the wire feeding speed includes the minimum wire feeding speed to the maximum wire feeding speed; wherein, the maximum wire feeding speed V 1≤Maximum permissible feed rate V max The maximum allowable feed rate is calculated based on the maximum allowable feed depth, and the minimum feed rate... V 2≥Minimum permissible feed rate V min The minimum allowable feed rate is calculated based on the minimum allowable feed depth. The feeding speed, periodic function, minimum feeding speed, and maximum feeding speed satisfy the following formula: or in, V For wire feeding speed, V 1 represents the maximum wire feeding speed and V 2 represents the minimum feed rate. f ( t ) is a basic elementary periodic function.

8. A method for periodically and gradually increasing the speed of cored wire feeding according to claim 7, characterized in that, The basic elementary periodic functions include sine wave function, cosine wave function, and sawtooth wave function.

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