A slag supplement method and device for electroslag fusion welding

Abstract

The present invention relates to the field of metallurgical technology, and particularly relates to a slag replenishment method and a slag replenishment device for electroslag fusion welding. The slag replenishment method includes: S1: Collecting the working condition parameters of electroslag fusion welding, and determining the rated electrode melting rate and the rated welding current according to the working condition parameters; S2: Comparing the monitored welding current with the rated welding current, and obtaining the first electrode melting rate or the second electrode melting rate according to the comparison result; S3: Comparing the first electrode melting rate or the second electrode melting rate with the rated electrode melting rate, and obtaining the third electrode melting rate or the fourth electrode melting rate according to the comparison result; S4: Comparing the third electrode melting rate or the fourth electrode melting rate with the rated electrode melting rate until the third electrode melting rate or the fourth electrode melting rate is within the normal fluctuation range of the rated electrode melting rate. Through the slag replenishment method and the slag replenishment device of the present invention, the constant melting rate control of electroslag fusion welding is realized, the stable solidification rate of the molten steel is ensured, and it is beneficial to keep the mechanical properties inside the fusion welded component uniform.

Description

Technical Field

[0001] The present invention relates to the field of metallurgical technology, and particularly to a slag replenishment method and a slag replenishment device for electroslag fusion welding. Background Art

[0002] With the continuous and in-depth development of China's industrial modernization, the demand for major equipment in all walks of life is increasing day by day. Especially in the field of high-end manufacturing, the demand for heavy equipment made of high-quality special steel is even more urgent. Among them, the large-scale of equipment has become a core concern, which requires materials to not only have excellent properties such as high strength and high toughness, but also meet the manufacturing requirements of large sizes. Therefore, the electroslag fusion welding technology has emerged. This technology uses a plate-shaped consumable electrode and an appropriate amount of molten slag, and under the precise control of the welding spacing, fuses two or more small-sized electroslag parts to "piece together" into a large-sized electroslag product. The advantages of this technology are that it not only meets the needs of large-scale production, but also effectively inherits the excellent properties of small-sized electroslag products through the secondary manufacturing process, such as high strength, high toughness, good corrosion resistance, and precise dimension control. In addition, compared with integral forging, the electroslag fusion welding technology greatly reduces the generation of metal waste, improves resource utilization rate, reduces production costs, shortens the production cycle, and improves production efficiency.

[0003] In the current electroslag fusion welding, during the welding process of the plate-shaped consumable electrode and the welded part, since the two materials are the same, the phenomenon of the slag pool melting and extending inward to the welded part will occur during welding. As the welding process continues, the horizontal cross-sectional area of the slag pool will gradually increase, while the depth of the slag pool will decrease accordingly, and the shape of the slag pool will gradually change from deep and narrow to shallow and wide. The above-mentioned shape change of the slag pool not only increases the risk of the welded part being melted through in the horizontal direction, but also expands the influence area of the welding, which in turn leads to problems such as deformation and uneven mechanical properties of the welded part.

[0004] And because the width of the welding pool is relatively narrow and the total amount of molten slag is limited, as the slag pool melts and extends inward to the welded part, its horizontal cross-sectional area continuously increases while the depth of the slag pool continuously decreases, resulting in an increasingly limited adjustment space for the movement position of the consumable electrode in the slag pool. And because the electroslag fusion welding technology usually adopts the constant power control method, the current fluctuation amplitude is relatively large during this process. And this technology changes the resistance value in the closed loop by adjusting the immersion depth of the consumable electrode in the slag pool, and its working principle is similar to that of a sliding rheostat. Therefore, during the welding process, the movement position and the immersion depth of the consumable electrode will also fluctuate greatly. As the electroslag fusion welding progresses, on the one hand, the depth of the slag pool continuously decreases, and on the other hand, the immersion depth of the electrode fluctuates greatly. The combined action of these two factors will generate a relatively large short-circuit risk.

[0005] To this end, the present application provides a slag replenishment method and a slag replenishment device for electroslag fusion welding. Summary of the Invention

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a slag replenishment method and a slag replenishment device for electroslag fusion welding, thereby solving the technical problems of deformation and uneven mechanical properties of the welded component during the welding process of the plate-shaped consumable electrode and the welded component, as well as the risk of short circuit easily caused by the continuous decrease of the slag pool depth and the large fluctuation of the electrode immersion depth.

[0007] To achieve the above object, the first aspect of the present invention provides a slag replenishment method for electroslag fusion welding, which specifically includes:

[0008] S1: Collect the working condition parameters of electroslag fusion welding, and determine the rated electrode melting rate and the rated welding current according to the working condition parameters;

[0009] S2: Compare the monitored welding current with the rated welding current. When the welding current is greater than or equal to the rated welding current, the automatic control computer controls the electrode lifting device to lift the plate-shaped consumable electrode, reduce the electrode melting rate, lower the welding current, and then calculate the first electrode melting rate through the automatic weighing device;

[0010] Record the weight increase of the automatic weighing device per unit time and the weight of the supplementary slag per unit time, and then calculate the first weight increase caused by the falling of the metal droplets generated by the melting of the electrode;

[0011] When the welding current is greater than the rated welding current:

[0012] ;

[0013] Wherein, is the first weight increase caused by the falling of the metal droplets generated by the melting of the plate-shaped consumable electrode per unit time, with the unit of kg; is the weight increase of the automatic weighing device per unit time, with the unit of kg; is the weight of the supplementary slag per unit time, with the unit of kg;

[0014] Then, according to the first weight increase caused by the falling of the metal droplets generated by the melting of the electrode per unit time, calculate the first electrode melting rate as:

[0015] ;

[0016] Wherein, is the first electrode melting rate, with the unit of kg / s; is the first weight gain caused by the falling of metal droplets generated by the melting of the plate consumable electrode per unit time, with the unit of kg; is the unit time, with the unit of s;

[0017] When the welding current is less than the rated welding current, the automatic control computer controls the electrode lifting device to lower the plate consumable electrode, increase the electrode melting speed, raise the welding current, and then obtain the second electrode melting speed through the automatic weighing device;

[0018] When the welding current is less than the rated welding current:

[0019] ;

[0020] Among them, is the second weight gain caused by the falling of metal droplets generated by the melting of the plate consumable electrode per unit time, with the unit of kg; is the weight gain of the automatic weighing device per unit time, with the unit of kg; is the weight of the supplementary slag per unit time, with the unit of kg;

[0021] Then, according to the second weight gain caused by the falling of metal droplets generated by the melting of the plate consumable electrode per unit time, the second electrode melting speed is calculated as:

[0022] ;

[0023] Among them, is the second electrode melting speed, with the unit of kg / s; is the second weight gain caused by the falling of metal droplets generated by the melting of the plate consumable electrode per unit time, with the unit of kg; is the unit time, with the unit of s.

[0024] S3: Compare the first electrode melting speed or the second electrode melting speed with the rated electrode melting speed. When the first electrode melting speed or the second electrode melting speed is greater than or equal to the preset electrode melting speed, the automatic control computer closes the slag replenisher, makes the depth of the slag pool shallower, reduces the immersion depth of the electrode, and then reduces the electrode melting speed, and obtains the third electrode melting speed through the automatic weighing device;

[0025] Compare the first electrode melting speed or the second electrode melting speed with the rated electrode melting speed. When the first electrode melting speed or the second electrode melting speed is greater than or equal to the rated electrode melting speed, close the slag replenisher;

[0026] ;

[0027] Among them, is the third weight gain caused by the falling of metal droplets generated by the melting of the plate consumable electrode per unit time, with the unit of kg; is the weight increase of the automatic weighing device per unit time, with the unit of kg; is the weight of the supplementary slag per unit time, with the unit of kg;

[0028] ;

[0029] Among them, is the melting rate of the third electrode, with the unit of kg / s; is the third weight increase caused by the falling of metal droplets due to the melting of the plate-shaped consumable electrode per unit time, with the unit of kg; is the unit time, with the unit of s;

[0030] When the melting rate of the first electrode or the second electrode is less than the rated electrode melting rate, the automatic control computer turns on the slag replenisher, making the depth of the slag pool deeper and the immersion depth of the electrode larger, thereby increasing the electrode melting rate, and obtaining the melting rate of the fourth electrode through the automatic weighing device;

[0031] When the melting rate of the first electrode or the second electrode is less than the rated electrode melting rate, the slag replenisher is turned on, and the slag replenishing speed is calculated from the difference between the melting rate of the first electrode or the second electrode and the rated electrode melting rate:

[0032] ;

[0033] Among them, is the difference in electrode melting rate, with the unit of kg / s; is the rated electrode melting rate, with the unit of kg / s; is the melting rate of the first electrode, with the unit of kg / s; is the melting rate of the second electrode, with the unit of kg / s;

[0034] ;

[0035] Among them, is the fourth weight increase caused by the falling of metal droplets due to the melting of the plate-shaped consumable electrode per unit time, with the unit of kg; is the weight increase of the automatic weighing device per unit time, with the unit of kg; is the weight of the supplementary slag per unit time, with the unit of kg;

[0036] ;

[0037] Among them, is the melting rate of the fourth electrode, with the unit of kg / s; is the fourth weight increase caused by the falling of metal droplets due to the melting of the plate-shaped consumable electrode per unit time, with the unit of kg; is the unit time, with the unit of s.

[0038] S4: Compare the melting rate of the third electrode or the fourth electrode with the rated electrode melting rate. When the melting rate of the third electrode or the fourth electrode is within the range of 95% to 105% of the rated electrode melting rate, the melting rate of the third electrode or the fourth electrode is within the normal fluctuation range of the rated electrode melting rate, achieving a constant electrode melting rate.

[0039] When the melting rate of the third electrode or the fourth electrode is outside the range of 95% to 105% of the rated electrode melting rate, repeat steps S3 and S4 until the melting rate of the third electrode or the fourth electrode is equal to the rated electrode melting rate, achieving a constant electrode melting rate.

[0040] Step S5 specifically includes:

[0041] S51: Calculate the preset electrode immersion depth based on the rated electrode melting rate.

[0042] S511: The latent heat used to melt the plate-shaped consumable electrode is calculated from the rated electrode melting rate and the latent heat of fusion per unit mass of the metal:

[0043] ;

[0044] Where, Q L is the latent heat used to melt the plate-shaped consumable electrode, in W; is the rated electrode melting rate, in kg / s; L is the latent heat of fusion per unit mass of the metal, in J / kg;

[0045] S512: Since the temperature in the width direction inside the plate-shaped consumable electrode is uniformly distributed, the sensible heat for heat conduction of the plate-shaped consumable electrode inside the plate-shaped consumable electrode is:

[0046] ;

[0047] Where, Q S is the sensible heat for heat conduction of the plate-shaped consumable electrode, in W; k m is the thermal conductivity of the metal, in W / (m·K); l e is the length of the plate-shaped consumable electrode, in m; w e is the width of the plate-shaped consumable electrode, in m;

[0048] S513: According to the heat balance relationship, the heat flux at the contact surface between the slag pool and the plate-shaped consumable electrode is equal to the sum of the latent heat used to melt the plate-shaped consumable electrode and the sensible heat for heat conduction of the plate-shaped consumable electrode:

[0049] ;

[0050] Among them, Q s-e is the heat flux at the contact surface between the slag pool and the plate-shaped consumable electrode, with the unit of W; Q L is the latent heat used to melt the plate-shaped consumable electrode, with the unit of W; Q S is the sensible heat used for heat conduction of the plate-shaped consumable electrode, with the unit of W;

[0051] S514: Calculate the area of the contact surface between the slag pool and the plate-shaped consumable electrode according to Fourier's law:

[0052] ;

[0053] Among them, A s-e is the area of the contact surface between the slag pool and the plate-shaped consumable electrode, with the unit of m 2 ; k l is the liquid-phase thermal conductivity of the metal, with the unit of W / (m·K); T 1 is the molten slag temperature at the contact surface between the slag pool and the plate-shaped consumable electrode, with the unit of K; T 2 is the solidus temperature of the metal, with the unit of K; Q s-e is the heat flux at the contact surface between the slag pool and the plate-shaped consumable electrode, with the unit of W; δ is the thickness of the metal liquid film, with the unit of mm;

[0054] S515: Calculate the preset electrode immersion depth from the contact surface area between the slag pool and the plate-shaped consumable electrode:

[0055] ;

[0056] Among them, h p is the preset electrode immersion depth, with the unit of m; A s-e is the contact surface area between the slag pool and the plate-shaped consumable electrode, with the unit of m 2 ; l e is the length of the plate-shaped consumable electrode, with the unit of m; w e is the width of the plate-shaped consumable electrode, with the unit of m.

[0057] S52: The automatic control computer obtains the maximum metal immersion depth based on the currently monitored and calculated electrode immersion depth, maximum metal droplet height, and maximum downward movement distance of the plate-shaped consumable electrode, then obtains the preset maximum metal immersion depth based on the maximum metal droplet height and the preset electrode immersion depth, and compares the maximum metal immersion depth with the preset maximum metal immersion depth:

[0058] S521: Record the total weight gain of the automatic weighing device and the total weight gain of the supplementary slag, and then calculate the total weight gain caused by the falling of metal droplets due to the melting of the plate-shaped consumable electrode;

[0059] ;

[0060] Wherein, is the total weight gain of the automatic weighing device, in kg; is the total weight gain caused by the falling of metal droplets due to electrode melting, in kg; is the total weight gain of the supplementary slag, in kg;

[0061] S522: Considering the slag density and metal density, calculate the increase in the slag-air interface height caused by the total weight gain of the automatic weighing device;

[0062] ;

[0063] Wherein, is the volume increase caused by the falling of metal droplets and slag replenishment, in m 3 ; is the total weight gain caused by the falling of metal droplets due to the melting of the plate-shaped consumable electrode, in kg; is the total weight gain of the supplementary slag, in kg; ρ m is the metal density, in kg / m 3 ; ρ s is the slag density, in kg / m 3 ;

[0064] ;

[0065] Wherein, is the increase in the slag-air interface height caused by the total weight gain of the automatic weighing device, in m; w z is the width of the fusion welding area, in m; l z is the length of the fusion welding area, in m;

[0066] S523: Since the immersion of the plate-shaped consumable electrode in the slag pool causes the height of the slag pool to rise, the slag-air interface height is corrected by the electrode immersion depth;

[0067] ;

[0068] Wherein, is the volume of the plate-shaped consumable electrode immersed in the slag pool, in m 3 ;h p is the preset electrode immersion depth, in m; l e is the length of the plate-shaped consumable electrode, in m; w e is the width of the plate-shaped consumable electrode, in m;

[0069] ;

[0070] Among them, is the increment of the molten slag-air interface height caused by the immersion of the plate-shaped consumable electrode into the slag bath, in m; is the volume of the plate-shaped consumable electrode immersed inside the slag bath, in m 3 ; w z is the width of the fusion welding area, in m; l z is the length of the fusion welding area, in m;

[0071] ;

[0072] Among them, is the total increment of the molten slag-air interface height, in m; is the increment of the molten slag-air interface height caused by the total weight gain of the automatic weighing device, in m; is the increment of the molten slag-air interface height caused by the immersion of the plate-shaped consumable electrode into the slag bath, in m;

[0073] Finally, the initial molten slag-air interface height is calculated from the initial molten slag volume, the length of the fusion welding area, and the width of the fusion welding area, and then the current molten slag-air interface height is calculated from the total increment of the molten slag-air interface height;

[0074] ;

[0075] Among them, h a-s_i is the molten slag-air interface height, in m; m i_s is the initial mass of the molten slag, in kg; ρ s is the molten slag density, in kg / m 3 ; w z is the width of the fusion welding area, in m; l z is the length of the fusion welding area, in m; is the total increment of the molten slag-air interface height, in m;

[0076] S524: During the electroslag fusion welding process, the welding current fluctuates. If the movement position of the plate-shaped consumable electrode changes due to the current fluctuation, the change law of the welding current is as follows:

[0077] ;

[0078] Among them, I is the welding current, with the unit of A; I r is the rated welding current, with the unit of A; ω 0is the angular frequency determined by the working frequency of the industrial AC power supply, with the unit of Hz; θ 0is the initial phase of the rated welding current;

[0079] ;

[0080] Among them, v e is the actual movement speed of the plate-shaped consumable electrode, with the unit of m / s; v 0 is the average movement speed of the plate-shaped consumable electrode, with the unit of m / s; v v is the fluctuating movement speed of the plate-shaped consumable electrode, with the unit of m / s; ω 1is the angular frequency of the movement of the plate-shaped consumable electrode, with the unit of Hz; θ 1is the initial phase of the movement of the plate-shaped consumable electrode, which is determined by the actual working conditions and calculated from the data recorded by the electrode lifting device;

[0081] ;

[0082] Among them, S e_d is the maximum downward movement distance of the plate-shaped consumable electrode, with the unit of m; [t 1 ，t 2 ] is the time interval of the downward movement speed of the plate-shaped consumable electrode, with the unit of s; v e is the actual movement speed of the plate-shaped consumable electrode, with the unit of m / s;

[0083] S525: Calculate the maximum metal immersion depth, including the current electrode immersion depth h a-s_i -h e_p 、the maximum metal droplet height h d and the maximum downward movement distance of the plate-shaped consumable electrode S e_d ;

[0084] ;

[0085] wherein, is the maximum metal immersion depth, in m; h a-s_i -h e_p is the current electrode immersion depth, in m; h e_p is the position of the electrode end recorded by the electrode lifting device, in m; h d is the maximum metal droplet height, in m; S e_d is the maximum downward movement distance of the plate-shaped consumable electrode, in m;

[0086] ;

[0087] wherein, is the maximum metal immersion depth, in m; h p is the preset electrode immersion depth, in m; h d is the maximum metal droplet height, in m; ( h p + h d ) is the preset maximum metal immersion depth, in m; C is the safety factor;

[0088] Furthermore, a safety factor is introduced to correct the preset maximum metal immersion depth, and then the maximum metal immersion depth is compared with the preset maximum metal immersion depth.

[0089] When the maximum metal immersion depth is greater than or equal to 110% - 130% of the preset maximum metal immersion depth, the electrode limit device is activated, and the automatic control computer controls the electrode lifting device to prevent the plate-shaped consumable electrode from moving downward, reducing the rated welding current and the rated electrode melting speed. In the case where the electro-slag fusion welding of the welded component is not completed, steps S2 to S5 are repeatedly executed until the electro-slag fusion welding of the welded component is completed;

[0090] When the maximum metal immersion depth is less than 110% - 130% of the preset maximum metal immersion depth, the automatic control computer controls the plate-shaped consumable electrode to continue moving downward until the electro-slag fusion welding of the welded component is completed.

[0091] The second aspect of the present invention provides a slag replenishing device, which is applied to the slag replenishing method for electroslag fusion welding provided by the first aspect. The slag replenishing device includes: an automatic weighing device; a welding component placed above the automatic weighing device; a slag pool located between two welding components; an electrode protection cover supported and connected to an external support rod to be arranged above the welding component; a slag replenisher arranged below the electrode protection cover and connected to the electrode protection cover, and the slag outlet of the slag replenisher faces the slag pool; an electrode lifting device supported and connected to an external support rod to be arranged above the slag pool; an electrode limiting device arranged below the electrode lifting device and connected to the electrode lifting device; a plate-shaped consumable electrode arranged below the electrode limiting device and inserted into the slag pool; an automatic control computer arranged outside the automatic weighing device and electrically connected to the automatic weighing device, the electrode protection cover, the slag replenisher, the plate-shaped consumable electrode, the electrode limiting device, and the electrode lifting device.

[0092] Optionally, a bottom cooling water tank is arranged between the automatic weighing device and the welding component to cool the welding component and the slag pool.

[0093] Optionally, the number of slag replenishers is multiple.

[0094] Optionally, multiple slag replenishers are evenly spaced in the circumferential direction of the plate-shaped consumable electrode.

[0095] The beneficial effects of the present invention are as follows:

[0096] The present invention provides a slag replenishing method and a slag replenishing device for electroslag fusion welding. The automatic control computer adjusts the lifting or lowering of the plate-shaped consumable electrode to change the electrode immersion depth, so that the welding current is maintained at the rated welding current, thereby obtaining the corresponding electrode melting rate (including the first electrode melting rate, the second electrode melting rate, the third electrode melting rate, or the fourth electrode melting rate). Then, according to the magnitude relationship or difference between the corresponding electrode melting rate and the rated electrode melting rate, the slag replenishing amount of the slag replenisher to the slag pool is adjusted in a timely manner or the slag replenishment is stopped, realizing the control of the electrode immersion depth, maintaining the stability of the slag pool depth, and ensuring that the electrode melting rate is equal to the rated electrode melting rate under the condition of stable slag pool temperature. Through the slag replenishing method and the slag replenishing device of the present invention, the constant melting rate control of electroslag fusion welding can be realized. The stable electrode melting rate can ensure the stable solidification rate of the molten steel, improve the element segregation of elements such as carbon, sulfur, phosphorus, and molybdenum in the vertical direction, and at the same time improve the uneven distribution of non-metallic inclusions in the vertical direction. These are all beneficial to maintaining the uniformity of the mechanical properties inside the welding component and improving its mechanical properties and service life.

[0097] Furthermore, since the electrode melting rate is guaranteed to be equal to the rated electrode melting rate, that is, the constant melting rate control is achieved, the total welding time can be increased or shortened by adjusting the rated electrode melting rate, and the heat transferred from the slag pool to the fusion welding component can be regulated, thereby controlling the cross-sectional horizontal melting depth of the fusion welding component and the volume of the fusion welding affected area, avoiding the deformation of the fusion welding component caused by excessive cross-sectional horizontal melting depth, making the mechanical properties inside the fusion welding component more uniform, and ultimately improving the quality of electroslag fusion welding.

[0098] Furthermore, the slag replenishment method and device of the present invention can control the depth of the slag pool by continuous slag replenishment, adjust the electrode melting rate, increase or shorten the total welding time, and regulate the heat transferred from the slag pool to the fusion welding component, so as to keep the cross-sectional horizontal melting depth of the fusion welding component stable, break through the welding height limit under the conventional constant power control strategy, and achieve the electroslag fusion welding of components with larger geometric dimensions.

[0099] Furthermore, the slag replenishment device is provided with an electrode position limiting device and cooperates with the automatic weighing device to enable the automatic control computer to obtain the maximum metal immersion depth and the preset maximum metal immersion depth. Based on the comparison result of the two, it is judged whether to activate the electrode position limiting device, and the plate-shaped consumable electrode is driven to move upward or downward by the electrode lifting device, ensuring the stability of the maximum metal immersion depth. With such a setting, the contact between the plate-shaped consumable electrode and the metal surface of the slag pool is effectively avoided, the short-circuit risk in the electroslag fusion welding process is eliminated, and the safety of the fusion welding system is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0100] Figure 1 It is a schematic flow chart of the slag replenishment method for electroslag fusion welding slag replenishment of the present invention;

[0101] Figure 2 It is a schematic structural diagram of the slag replenishment device for electroslag fusion welding slag replenishment of the present invention;

[0102] Figure 3 It is a numerical simulation calculation cloud diagram of the maximum metal droplet height by ANSYS-Fluent software when the current electrode immersion depth is 0.020 m in the present invention;

[0103] Figure 4 It is a numerical simulation calculation cloud diagram of the maximum metal droplet height by ANSYS-Fluent software when the current electrode immersion depth is 0.030 m in the present invention;

[0104] Figure 5 It is a numerical simulation calculation cloud diagram of the maximum metal droplet height by ANSYS-Fluent software when the current electrode immersion depth is 0.040 m in the present invention.

[0105] Description of the reference numerals in the drawings: 1. Electrode lifting device; 2. Electrode limiting device; 3. Electrode protective cover; 4. Plate-shaped consumable electrode; 5. Slag feeder; 6. Control valve; 7. Fusion welding component; 8. Slag pool; 9. Automatic weighing device; 10. Industrial AC power supply; 11. Automatic control computer; 12. Bottom cooling water tank; 13. Metal molten pool. Detailed implementation manners

[0106] To better understand the above technical solution, the exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and the scope of the present invention can be completely conveyed to those skilled in the art.

[0107] An embodiment of the present invention provides a slag feeding method for electroslag fusion welding, as Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 shown, the slag feeding method includes:

[0108] S1: Collect the working condition parameters of electroslag fusion welding, and determine the rated electrode melting rate and the rated welding current according to the working condition parameters; specifically including material physical properties, slag parameters and process parameters, as shown in Table 1.

[0109] Table 1 Working condition parameters of the electroslag fusion welding process in this embodiment

[0110] Operating condition parameters Value Physical properties of materials (material grade: ZG04Cr13Ni5Mo) <![CDATA[Metal density, kg / m 3 > 7300(1578K) Thermal conductivity of metal, W / m·K 20.38(603K); 30.85(1503K) 34.21(1713K); 35.87(2003K) Liquidus / solidus temperature of metal, K 1747 / 1578 Latent heat of fusion per unit mass of metal, J / kg 180000 <![CDATA[Slag parameters (CaF2 - matrix)]]> <![CDATA[The density of slag, kg / m 3 > 2350 Process parameters Length of fusion welding area, m 1 Width of fusion welding area, m 0.06 Length of plate-shaped consumable electrode, m 0.96 Thickness of plate-shaped consumable electrode, m 0.02 Rated electrode melting rate, kg / s 0.78304 Initial slag weight, kg 9.9 Initial slag pool height, m 0.07 Rated welding current, A 12000 ;

[0111] S2: Compare the monitored welding current of 12500 A with the rated welding current of 12000 A. Since the welding current of 12500 A is greater than the rated welding current of 12000 A, the automatic control computer 11 controls the electrode lifting device 1 to lift the plate-shaped consumable electrode 4 by 2 mm, then the electrode melting rate decreases, the welding current drops, and the first electrode melting rate is calculated through the automatic weighing device 9;

[0112] Record the weight increase of the automatic weighing device 9 per unit time, and the weight of the supplementary molten slag obtained by the slag feeder 5, and then calculate the first weight increase caused by the falling of the metal droplets melted from the plate-shaped consumable electrode 4; because the total working time of the electroslag fusion welding process is relatively short, basically within 1 hour, and the total amount of molten slag is small, the consumption of molten slag is ignored; and before the fusion welding starts, the crushed and preheated and baked molten slag is loaded into the slag feeder 5 for use when the slag pool 8 needs to be supplemented with slag.

[0113] When the welding current of 12500 A is greater than the rated welding current of 12000 A:

[0114] ;

[0115] Among them, is the first weight increase caused by the falling of metal droplets generated by the melting of the plate-shaped consumable electrode 4 per unit time, totaling 5 kg; is the weight increase of the automatic weighing device 9 per unit time, totaling 5.2 kg; is the weight of the supplementary slag per unit time, totaling 0.2 kg;

[0116] Then, according to the first weight increase caused by the falling of metal droplets generated by the melting of the plate-shaped consumable electrode 4 per unit time, the first electrode melting rate is calculated as:

[0117] ;

[0118] Among them, is the first electrode melting rate, calculated to be 1 kg / s; is the first weight increase caused by the falling of metal droplets generated by the melting of the plate-shaped consumable electrode 4 per unit time, totaling 5 kg; is the unit time, totaling 5 s;

[0119] When the welding current of 11500 A is less than the rated welding current of 12000 A, the automatic control computer 11 controls the electrode lifting device 1 to lower the plate-shaped consumable electrode 4 by 2 mm, the electrode melting rate increases, the welding current rises, and then the second electrode melting rate is obtained through the automatic weighing device 9;

[0120] When the welding current of 11500 A is less than the rated welding current of 12000 A:

[0121] ;

[0122] Among them, is the second weight increase caused by the falling of metal droplets generated by the melting of the plate-shaped consumable electrode 4 per unit time, totaling 2.5 kg; is the weight increase of the automatic weighing device 9 per unit time, totaling 2.6 kg; is the weight of the supplementary slag per unit time, totaling 0.1 kg;

[0123] Then, according to the second weight increase caused by the falling of metal droplets generated by the melting of the plate-shaped consumable electrode 4 per unit time, the second electrode melting rate is calculated as:

[0124] ;

[0125] Among them, is the melting rate of the second electrode, and the calculated value is 0.5 kg / s; is the second weight increase caused by the falling of metal droplets generated by the melting of the plate-shaped consumable electrode 4 per unit time, with a total of 2.5 kg; is the unit time, with a total of 5 s.

[0126] S3: Compare the melting rate of the first electrode or the melting rate of the second electrode with the rated electrode melting rate of 0.78304 kg / s. When the melting rate of the first electrode or the melting rate of the second electrode is greater than or equal to the preset electrode melting rate, the automatic control computer 11 closes the slag feeder 5, making the depth of the slag pool 8 shallower, reducing the immersion depth of the electrode, and thus reducing the electrode melting rate. The melting rate of the third electrode is obtained through the automatic weighing device 9;

[0127] In this embodiment, the melting rate of the first electrode is 1 kg / s, which is greater than the rated electrode melting rate of 0.78304 kg / s. Therefore, it is necessary to close the slag feeder 5;

[0128] ;

[0129] Among them, is the third weight increase caused by the falling of metal droplets generated by the melting of the plate-shaped consumable electrode 4 per unit time, with a total of 3.9 kg; is the weight increase of the automatic weighing device 9 per unit time, with a total of 3.9 kg; is the weight of the supplementary slag per unit time, with a total of 0 kg;

[0130] ;

[0131] Among them, is the melting rate of the third electrode, and the calculated value is 0.78 kg / s; is the third weight increase caused by the falling of metal droplets generated by the melting of the plate-shaped consumable electrode 4 per unit time, with a total of 3.9 kg; is the unit time, with a total of 5 s;

[0132] When the melting rate of the first electrode or the melting rate of the second electrode is less than the rated electrode melting rate of 0.78304 kg / s, the automatic control computer 11 opens the slag feeder 5, making the depth of the slag pool 8 deeper, increasing the immersion depth of the electrode, and thus increasing the electrode melting rate. The melting rate of the fourth electrode is obtained through the automatic weighing device 9;

[0133] In this embodiment, the melting rate of the second electrode is 0.5 kg / s, which is less than the rated electrode melting rate of 0.78304 kg / s. The slag feeder 5 is turned on, and the slag feeding speed is calculated from the difference between the melting rate of the first electrode or the second electrode and the rated electrode melting rate. In this embodiment, the slag feeding speed is determined by the difference between the melting rate of the second electrode, 0.5 kg / s, and the rated electrode melting rate, 0.78304 kg / s, that is, -0.28304 kg / s:

[0134] ;

[0135] Among them, is the difference in electrode melting rate, and -0.28304 kg / s is calculated; is the rated electrode melting rate, which is 0.78304 kg / s; is the melting rate of the second electrode, which is 0.5 kg / s; the difference in electrode melting rate in this embodiment is -0.28304 kg / s, and the slag feeding amount is 0.5 kg. The slag feeding amount is adjusted according to the ratio under other conditions of the difference in electrode melting rate.

[0136] ;

[0137] Among them, is the fourth weight increase caused by the falling of metal droplets generated by the melting of the plate-shaped consumable electrode 4 per unit time, totaling 3.8 kg; is the weight increase of the automatic weighing device 9 per unit time, totaling 4.3 kg; is the weight of the supplementary slag per unit time, 0.5 kg;

[0138] ;

[0139] Among them, is the melting rate of the fourth electrode, and 0.76 kg / s is calculated; is the fourth weight increase caused by the falling of metal droplets generated by the melting of the plate-shaped consumable electrode 4 per unit time, totaling 3.8 kg; is the unit time, totaling 5 s.

[0140] S4: Compare the melting rate of the third electrode, 0.78 kg / s, or the melting rate of the fourth electrode, 0.76 kg / s, with the rated electrode melting rate of 0.78304 kg / s. When the melting rate of the third electrode or the fourth electrode is within the range of 95% - 105% of the rated electrode melting rate, the melting rate of the third electrode or the fourth electrode is within the normal fluctuation range of the rated electrode melting rate, and the constancy of the electrode melting rate is achieved;

[0141] When the melting rate of the third electrode or the fourth electrode is outside the range of 95% to 105% of the rated electrode melting rate, steps S3 and S4 are repeated until the melting rate of the third electrode or the fourth electrode is within the normal fluctuation range of the rated electrode melting rate, achieving a constant electrode melting rate.

[0142] Step S5 specifically includes:

[0143] S51: Calculate the preset electrode immersion depth based on the rated electrode melting rate;

[0144] S511: The latent heat used to melt the plate-shaped consumable electrode 4 is calculated from the rated electrode melting rate and the latent heat of melting per unit mass of the metal:

[0145] ;

[0146] Among them, Q L is the latent heat used to melt the plate-shaped consumable electrode, in W; is the rated electrode melting rate, 0.78304 kg / s; L is the latent heat of melting per unit mass of the metal, in J / kg; the rated electrode melting rate in this embodiment is 0.78304 kg / s, and the latent heat of melting per unit mass of the metal is 180,000 J / kg, then the calculated Q L is 140947.2 W.

[0147] S512: Since the temperature in the width direction inside the plate-shaped consumable electrode 4 is uniformly distributed, the sensible heat for heat conduction of the plate-shaped consumable electrode 4 inside the plate-shaped consumable electrode 4 is:

[0148] ;

[0149] Among them, Q S is the sensible heat for heat conduction of the plate-shaped consumable electrode 4, in W; k m is the thermal conductivity of the metal, in W / (m·K); l e is the length of the plate-shaped consumable electrode 4, 0.96 m; w e is the width of the plate-shaped consumable electrode 4, 0.02 m; the thermal conductivity of the metal in this embodiment is 32 W / m·K. During the welding process, the temperature gradient in the height direction of the plate-shaped consumable electrode 4 remains steady and can be calculated by numerical simulation methods. The temperature gradient in this embodiment is -37606 K / m, then the calculated Q S is 23105 W.

[0150] S513: According to the heat balance relationship, the heat flux at the contact surface between the slag pool 8 and the plate consumable electrode 4 is equal to the sum of the latent heat used to melt the plate consumable electrode 4 and the sensible heat used for heat conduction of the plate consumable electrode 4:

[0151] ;

[0152] Among them, Q s-e is the heat flux at the contact surface between the slag pool 8 and the plate consumable electrode 4, with the unit of W; Q L is the latent heat used to melt the plate consumable electrode 4, with the unit of W; Q S is the sensible heat used for heat conduction of the plate consumable electrode 4, with the unit of W; in this embodiment, Q s-e is 164052.2 W.

[0153] S514: In this embodiment, the temperature of the slag pool 8 is 1830 K, the metal solidus temperature is 1578 K, and the liquid-phase thermal conductivity of the metal is 32 W / (m·K). The area of the contact surface between the slag pool 8 and the plate consumable electrode 4 is calculated by Fourier's law:

[0154] ;

[0155] Among them, A s-e is the area of the contact surface between the slag pool 8 and the plate consumable electrode 4, with the unit of m 2 ; k l is the liquid-phase thermal conductivity of the metal, with the unit of W / (m·K); T 1 is the molten slag temperature at the contact surface between the slag pool 8 and the plate consumable electrode 4, with the unit of K; T 2 is the metal solidus temperature, with the unit of K; Q s-e is the heat flux at the contact surface between the slag pool 8 and the plate consumable electrode 4, with the unit of W; δ is the metal liquid film thickness, which is 3 mm; in this embodiment, A s-e is 0.061031 m 2 .

[0156] S515: The preset electrode immersion depth is calculated from the area of the contact surface between the slag pool 8 and the plate consumable electrode 4:

[0157] ;

[0158] Among them, h p is the preset electrode immersion depth, with the unit of m; A s-eis the area of the contact surface between the slag pool 8 and the plate-shaped consumable electrode 4, with the unit of m 2 ; l e is the length of the plate-shaped consumable electrode 4, with the unit of m; w e is the width of the plate-shaped consumable electrode 4, with the unit of m. In this embodiment, h p is 0.03 m.

[0159] S52: The automatic control computer 11 obtains the maximum metal immersion depth based on the currently monitored and calculated electrode immersion depth, maximum metal droplet height, and maximum downward movement distance of the plate-shaped consumable electrode 4, and then obtains the preset maximum metal immersion depth based on the maximum metal droplet height and the preset electrode immersion depth, and compares the maximum metal immersion depth with the preset maximum metal immersion depth:

[0160] S521: Record the total weight gain of the automatic weighing device 9 and the total weight gain of the supplementary slag, and then calculate the total weight gain caused by the falling of the metal droplets generated by the melting of the plate-shaped consumable electrode 4;

[0161] ;

[0162] Among them, is the total weight gain of the automatic weighing device 9, totaling 10.5 kg; is the total weight gain caused by the falling of the metal droplets generated by the melting of the plate-shaped consumable electrode 4, totaling 10 kg; is the total weight gain of the supplementary slag, totaling 0.5 kg;

[0163] S522: The high-temperature liquid slag and the high-temperature liquid metal are immiscible Newtonian fluids and the density of the slag is less than that of the metal. Therefore, regardless of how the shape of the slag pool 8 changes, the slag pool 8 is always located above the metal molten pool 13 and the liquid surface in contact with the air remains horizontal; considering the slag density and the metal density, calculate the height increment of the slag-air interface caused by the total weight gain of the automatic weighing device 9;

[0164] ;

[0165] Among them, is the volume increment caused by the falling of the metal droplets and the supplementary slag, and it is calculated to be 0.00158 m 3 ; is the total weight gain caused by the falling of the metal droplets generated by the melting of the plate-shaped consumable electrode 4, 10 kg; is the total weight gain of the supplementary slag, 0.5 kg; ρ m is the metal density, 7300 kg / m 3 ;ρ s is the slag density, 2350 kg / m 3 ;

[0166] ;

[0167] Among them, is the increment of the slag-air interface height caused by the total weight gain of the automatic weighing device 9, calculated to be 0.02638 m; w z is the width of the fusion welding area, 0.06 m; l z is the length of the fusion welding area, 1 m;

[0168] S523: Since the immersion of the plate-shaped consumable electrode 4 into the slag pool 8 causes the height of the slag pool 8 to rise, the height of the slag-air interface is corrected by the electrode immersion depth;

[0169] ;

[0170] Among them, is the volume of the plate-shaped consumable electrode 4 immersed inside the slag pool 8, calculated to be 0.000286 m 3 ; h p is the preset electrode immersion depth, 0.03 m; l e is the length of the plate-shaped consumable electrode 4, 0.96 m; w e is the width of the plate-shaped consumable electrode 4, 0.02 m;

[0171] ;

[0172] Among them, is the increment of the slag-air interface height caused by the immersion of the plate-shaped consumable electrode 4 into the slag pool 8, calculated to be 0.00477 m; is the volume of the plate-shaped consumable electrode 4 immersed inside the slag pool 8, 0.000286 m 3 ; w z is the width of the fusion welding area, 0.06 m; l z is the length of the fusion welding area, 1 m;

[0173] ;

[0174] Among them, is the total increment of the slag-air interface height, calculated to be 0.03115 m; The height increment of the slag-air interface caused by the total weight gain of the automatic weighing device 9 is calculated to be 0.02638 m; The height increment of the slag-air interface caused by the immersion of the plate-shaped consumable electrode 4 into the slag pool 8 is calculated to be 0.00477 m;

[0175] Finally, the initial slag-air interface height is calculated from the initial slag volume, the length of the fusion welding area, and the width of the fusion welding area, and then the current slag-air interface height is calculated from the total increment of the slag-air interface height;

[0176] ;

[0177] Among them, h a-s_i is the slag-air interface height, calculated to be 0.101363 m; m i_s is the initial mass of the slag, 9.9 kg; ρ s is the slag density, 2350 kg / m 3 ; w z is the width of the fusion welding area, 0.06 m; l z is the length of the fusion welding area, 1 m; is the total increment of the slag-air interface height, calculated to be 0.03115 m;

[0178] S524: During the electroslag fusion welding process, the welding current fluctuates. If the movement position of the plate-shaped consumable electrode 4 changes due to the current fluctuation, the change law of the welding current is as follows:

[0179] ;

[0180] Among them, I is the welding current, unit A; I r is the rated welding current, unit A; ω 0 is the angular frequency determined by the working frequency of the industrial AC power supply 10, unit Hz; θ 0 is the initial phase of the rated welding current; In this embodiment, the welding current changes with time. The rated welding current is 12000 A, and the power supply working frequency is the same as the industrial AC power frequency, both being 50 Hz. Then ω 0 is 314.15926, θ 0 is 0;

[0181] ;

[0182] Among them, ve is the actual moving speed of the plate-shaped consumable electrode 4, with the unit of m / s; v 0 is the average moving speed of the plate-shaped consumable electrode 4, with the unit of m / s; v v is the fluctuating moving speed of the plate-shaped consumable electrode 4, with the unit of m / s; ω 1 is the angular frequency of the movement of the plate-shaped consumable electrode 4, with the unit of Hz; θ 1 is the initial phase of the movement of the plate-shaped consumable electrode 4, which is determined by the actual working conditions and calculated from the data recorded by the electrode lifting device 1; in this embodiment v e is 0.09 m / s, v 0 is 0.087 m / s, v v is 0.003 m / s, ω 1 is 1 Hz, θ 1 is 0.

[0183] ;

[0184] Among them, S e_d is the maximum downward movement distance of the plate-shaped consumable electrode 4, with the unit of m; [t 1 ，t 2 ] is the time interval when the movement speed of the plate-shaped consumable electrode 4 is downward, with the unit of s; v e is the actual moving speed of the plate-shaped consumable electrode 4, with the unit of m / s; in this embodiment S e_d is 0.005 m.

[0185] S525: Since liquid metal is also a good conductor, when considering the short-circuit risk in the electroslag welding process, the maximum metal droplet height must be considered. According to the obtained current electrode immersion depth and the corresponding electrode melting rate, under the condition of the working condition parameters given in Table 1, the corresponding maximum metal droplet height is calculated by the numerical simulation software ANSYS-Fluent.

[0186] Figure 3When the current electrode immersion depth is 0.020 m, it is the ANSYS-Fluent software numerical simulation calculation contour map of the maximum metal droplet height. The statistically obtained maximum metal droplet height is 0.013 m. Combining with the electrode immersion depth, when the electrode immersion depth is 0.020 m, the preset maximum metal immersion depth of the slag replenishing device for electroslag fusion welding is 0.033 m, that is, the preset maximum immersion depth of the good conductor including the plate-shaped consumable electrode 4 and the metal droplet in the slag pool 8 is 0.033 m. This result is used to compare and judge with the maximum metal immersion depth in the actual welding process to control the start and stop of the electrode limit device 2.

[0187] Figure 4 When the current electrode immersion depth is 0.030 m, it is the ANSYS-Fluent software numerical simulation calculation contour map of the maximum metal droplet height. The statistically obtained maximum metal droplet height is 0.014 m, and the preset maximum metal immersion depth is 0.044 m. This result is used to compare with the maximum metal immersion depth in the actual welding process to control the start and stop of the electrode limit device 2.

[0188] Figure 5 When the current electrode immersion depth is 0.040 m, it is the ANSYS-Fluent software numerical simulation calculation contour map of the maximum metal droplet height. The statistically obtained maximum metal droplet height is 0.017 m, and the preset maximum metal immersion depth is 0.057 m. This result is used to compare with the maximum metal immersion depth in the actual welding process to control the start and stop of the electrode limit device 2.

[0189] Calculate the maximum metal immersion depth, including the current electrode immersion depth h a-s_i -h e_p and the maximum metal droplet height h d as well as the maximum downward movement distance of the plate-shaped consumable electrode 4 S e_d ;

[0190] ;

[0191] Among them, is the maximum metal immersion depth, in m; h a-s_i -h e_p is the current electrode immersion depth, in m; h e_p is the position of the electrode end recorded by the electrode lifting device 1, in m; h d is the maximum metal droplet height, in m; Se_d is the maximum downward movement distance of the plate-shaped consumable electrode 4, in m; in this embodiment h a-s_i -h e_p is 0.03115 m, h d is 0.014 m, S e_d is 0.005 m, is 0.05015 m.

[0192] Due to the inevitable position fluctuations of the plate-shaped consumable electrode 4 during the electroslag fusion welding process, such as feedback control delay, etc., in order to ensure the normal progress of the welding process and prevent the electrode limit device 2 from being started too frequently, a safety factor C needs to be set as the control margin. This safety factor C is set within the range of 1.1 to 1.3. During the actual production process, this safety factor C can be adjusted according to the initial slag amount and the start-stop state of the electrode limit device 2. Compare the corrected preset maximum metal immersion depth with the maximum metal immersion depth obtained through monitoring and calculation during the welding process for comparison;

[0193] When the maximum metal immersion depth is greater than or equal to 110% - 130% of the preset maximum metal immersion depth, then start the electrode limit device 2, and the automatic control computer 11 controls the electrode lifting device 1 to prevent the plate-shaped consumable electrode 4 from moving downward, reduce the rated welding current and the rated electrode melting rate. If the electro-slag fusion welding of the welded part 7 is not completed, then repeat steps S2 to S5 until the electro-slag fusion welding of the welded part 7 is completed;

[0194] When the maximum metal immersion depth is less than 110% - 130% of the preset maximum metal immersion depth, then the automatic control computer 11 controls the plate-shaped consumable electrode 4 to continue moving downward until the electro-slag fusion welding of the welded part 7 is completed.

[0195] ;

[0196] Among them, is the maximum metal immersion depth, in m; h p is the preset electrode immersion depth, in m; h d is the maximum metal droplet height, in m; ([[]]END]] h p + h d ) is the preset maximum metal immersion depth, in m; C is the safety factor; in this embodiment C is 1.1, ([[]]END]] hp + h d ) is 0.044 m, then 0.05015 m > 0.0484 m, start the electrode limit device 2 to prevent the plate-shaped consumable electrode 4 from moving downward.

[0197] During the actual electroslag fusion welding process, multiple steps S2 to S5 need to be repeatedly executed until the two welded parts 7 are completed. The specific number of repetitions needs to be determined according to the actual welding situation and will not be elaborated here.

[0198] It can be seen from the above embodiments that:

[0199] (1) By automatically adjusting the lifting (such as ±2 mm displacement) and slag replenishment amount of the plate-shaped consumable electrode 4, the fluctuation of the welding current is controlled within the range of ±4% of the rated value (such as 12000 A) (such as 12500 A to 12000 A), and the deviation of the electrode melting rate is limited within the range of ±5% (95% - 105% of the rated melting rate of 0.78304 kg / s);

[0200] (2) Calculate the electrode immersion depth (such as the preset value of 0.03 m) using the heat balance relationship, and dynamically calculate the maximum metal immersion depth (such as 0.05015 m) in combination with the safety factor (1.1 - 1.3). After the maximum metal immersion depth exceeds the safety value (0.0484), start the electrode limit device 2 to prevent the plate-shaped consumable electrode 4 from moving downward and cut off the short-circuit risk;

[0201] (3) The depth of the slag pool 8 is regulated by the slag replenishment device of this embodiment, the extension of the slag pool 8 in the horizontal direction is reduced, the horizontal melting depth of the welded part 7 is decreased, and the uniformity of the mechanical properties is improved;

[0202] (4) In the prior art, constant power control is used. Therefore, the inner side of the welded part 7 continuously melts, causing the slag pool 8 to extend to both sides, and the depth of the slag pool 8 decreases. To maintain the rated power, it is necessary to continuously reduce the electrode immersion depth, resulting in an increasingly smaller electrode melting rate. The Joule heat generated in the slag pool 8 is mainly transferred to the welded parts 7 on both sides, causing the slag pool 8 to continuously extend to both sides until the welded part 7 is melted through. Therefore, there is a welding height limit in the electroslag fusion welding under the constant power control strategy, and electroslag welding exceeding the height limit cannot be performed. However, the slag replenishment method of this embodiment can control the depth of the slag pool 8 by continuous slag replenishment, adjust the electrode melting rate, increase or shorten the total welding time, and regulate the heat transferred from the slag pool 8 to the welded part 7, so as to control the cross-sectional horizontal melting depth of the welded part 7 to remain stable. Therefore, it is not limited by the constant power and supports the electroslag fusion welding of larger-sized (such as with a height of more than 1 m) welded parts 7, and can be applied to the manufacturing of high-precision large-sized electroslag steel components.

[0203] An embodiment of the present invention further provides a slag replenishing device for electroslag fusion welding, as Figure 2 shown. The slag replenishing device includes: an automatic weighing device 9; a fusion welding component 7 disposed above the automatic weighing device 9; a slag pool 8 located between two fusion welding components 7; an electrode protection cover 3 supported and connected to an external support rod to be disposed above the fusion welding component 7; a slag replenisher 5 disposed below the electrode protection cover 3 and connected to the electrode protection cover 3, and the slag outlet of the slag replenisher 5 faces the slag pool 8; an electrode lifting device 1 supported and connected to an external support rod to be disposed above the slag pool 8; an electrode limiting device 2 disposed below the electrode lifting device 1 and connected to the electrode lifting device 1; a plate-shaped consumable electrode 4 disposed below the electrode limiting device 2 and inserted into the slag pool 8; and an automatic control computer 11 disposed outside the automatic weighing device 9 and electrically connected to the automatic weighing device 9, the electrode protection cover 3, the slag replenisher 5, the plate-shaped consumable electrode 4, the electrode limiting device 2, and the electrode lifting device 1.

[0204] Exemplarily, the automatic control computer 11 is disposed outside the automatic weighing device 9 and placed at a position convenient for operation by an operator according to actual needs, and then electrically connected to the automatic weighing device 9, the electrode protection cover 3, the slag replenisher 5, the plate-shaped consumable electrode 4, the electrode limiting device 2, and the electrode lifting device 1 through electric wires, so as to realize automatic control of the above components.

[0205] Exemplarily, the plate-shaped consumable electrode 4 is rigidly connected to the electrode protection cover 3 by clamping or welding. The electrode lifting device 1 is disposed directly above the electrode protection cover 3, and the electrode lifting device 1 and the electrode protection cover 3 can be connected by a screw nut or welded. The slag replenisher 5 and the electrode protection cover 3 are also connected by a screw nut or welded, which also belongs to a rigid connection.

[0206] Exemplarily, a control valve 6 is provided at the bottom of the slag replenisher 5 and is also electrically connected to the automatic control computer 11. When it is necessary to open the slag replenisher 5, the automatic control computer 11 opens the control valve 6, thereby realizing slag replenishment by the slag replenisher 5; when slag replenishment is not required, the automatic control computer 11 closes the control valve 6, thereby realizing stopping slag replenishment by the slag replenisher 5.

[0207] In a possible embodiment, as Figure 2 shown, a bottom cooling water tank 12 is disposed between the automatic weighing device 9 and the fusion welding component 7, so as to cool the fusion welding component 7 and the slag pool 8.

[0208] Exemplarily, the bottom cooling water tank 12 of this embodiment is only placed above the automatic weighing device 9 and below the fusion welding component 7. The bottom cooling water tank 12 cools the slag pool 8 and the fusion welding components 7 on both sides of the slag pool 8, so that the two fusion welding components 7 are accelerated to be welded into an integral body of the same material.

[0209] Exemplarily, both ends of the industrial AC power supply 10 are respectively connected to the plate-shaped consumable electrode 4 and the bottom cooling water tank 12, and the working voltage is adjusted according to the actual requirements of electroslag fusion welding. The range of the working voltage is 30V to 100V.

[0210] In a possible embodiment, as Figure 2 shown, the number of slag replenishers 5 is multiple.

[0211] Exemplarily, 2 slag replenishers 5 are provided in this embodiment. The 2 slag replenishers 5 are symmetrically arranged on both sides of the plate-shaped consumable electrode 4. The two symmetrically arranged slag replenishers 5 can evenly replenish the slag pool 8 from both sides of the plate-shaped consumable electrode 4 when the slag pool 8 needs to be replenished with slag, which is beneficial to evenly adjusting the depth of the slag pool 8.

[0212] In a possible embodiment, as Figure 2 shown, multiple slag replenishers 5 are evenly spaced and arranged in the circumferential direction of the plate-shaped consumable electrode 4.

[0213] Exemplarily, 3 slag replenishers 5 are provided in this embodiment. The 3 slag replenishers 5 are evenly spaced and arranged in the circumferential direction of the plate-shaped consumable electrode 4. The 3 slag replenishers 5 arranged in this way can evenly replenish the slag pool 8 from both sides of the plate-shaped consumable electrode 4 when the slag pool 8 needs to be replenished with slag, which is beneficial to evenly adjusting the depth of the slag pool 8.

[0214] In the present invention, unless otherwise clearly specified and defined, terms such as "installation", "connection", "connection", "fixation" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium; it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations. The first feature is "above" or "below" the second feature, which can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature is "above", "above" and "on" the second feature, which can be that the first feature is directly above or obliquely above the second feature, or only indicates that the first feature is at a higher horizontal height than the second feature. The first feature is "below", "below" and "under" the second feature, which can be that the first feature is directly below or obliquely below the second feature, or only indicates that the first feature is at a lower horizontal height than the second feature.

[0215] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A slag filling method for electroslag fusion welding, characterized in that: include: S1: Collect the working parameters of electroslag fusion welding, and determine the rated electrode melting speed and rated welding current according to the working parameters; S2: Compare the monitored welding current with the rated welding current. When the welding current is greater than or equal to the rated welding current, the computer automatically controls the electrode lifting device to lift the plate-type consumable electrode, reduce the electrode melting speed, and reduce the welding current. Then the first electrode melting speed is calculated by the automatic weighing device. Record the weight increase of the automatic weighing device per unit time and the weight of the slag added per unit time, and then calculate the first weight increase caused by the falling of the metal droplets generated by the melting of the plate-type consumable electrode; The first electrode melting speed is calculated based on the first weight increase caused by the falling of metal droplets generated by the melting of the plate-type consumable electrode per unit time; When the welding current is less than the rated welding current, the automatic computer controls the electrode lifting device to lower the plate-type consumable electrode, increase the electrode melting speed, increase the welding current, and then obtain the second electrode melting speed through the automatic weighing device; S3: Compare the first electrode melting speed or the second electrode melting speed with the rated electrode melting speed. When the first electrode melting speed or the second electrode melting speed is greater than or equal to the rated electrode melting speed, the computer is automatically controlled to close the slag feeder to make the slag pool shallower and the electrode immersion depth lower, thereby reducing the electrode melting speed, and obtaining the third electrode melting speed through the automatic weighing device; When the first electrode melting speed or the second electrode melting speed is less than the rated electrode melting speed, the automatic control computer starts the slag feeder to deepen the slag pool and increase the electrode immersion depth, thereby increasing the electrode melting speed, and the fourth electrode melting speed is obtained through the automatic weighing device; S4: comparing the melting speed of the third electrode or the melting speed of the fourth electrode with the rated electrode melting speed. When the melting speed of the third electrode or the melting speed of the fourth electrode is within the range of 95% to 105% of the rated electrode melting speed, the melting speed of the third electrode or the melting speed of the fourth electrode is within the normal fluctuation range of the rated electrode melting speed, and the electrode melting speed is constant. When the third electrode melting speed or the fourth electrode melting speed is outside the range of 95% to 105% of the rated electrode melting speed, steps S3 and S4 are repeated until the third electrode melting speed or the fourth electrode melting speed is within the normal fluctuation range of the rated electrode melting speed, thereby achieving a constant electrode melting speed.

2. The slag filling method for electroslag fusion welding according to claim 1, characterized in that: After step S4, step S5 is further provided, and step S5 specifically includes: S51: Calculate a preset electrode immersion depth according to a rated electrode melting rate; S52: The automatic control computer obtains the maximum metal immersion depth based on the current electrode immersion depth, the maximum metal droplet height and the maximum downward movement distance of the plate-type consumable electrode obtained through monitoring and calculation, and then obtains the preset maximum metal immersion depth based on the maximum metal droplet height and the preset electrode immersion depth, and compares the maximum metal immersion depth with the preset maximum metal immersion depth: When the maximum metal immersion depth is greater than or equal to 110% to 130% of the preset maximum metal immersion depth, the electric limit device is started, and the computer-controlled electrode lifting device is automatically controlled to prevent the plate-type consumable electrode from moving downward, thereby reducing the rated welding current and the rated electrode melting speed. If the electroslag fusion welding of the fusion welding parts is not completed, steps S2 to S5 are repeated until the electroslag fusion welding of the fusion welding parts is completed; When the maximum metal immersion depth is less than 110% to 130% of the preset maximum metal immersion depth, the automatic control computer controls the plate-type consumable electrode to continue to move downward until the electroslag fusion welding of the fusion welding parts is completed.

3. The slag filling method for electroslag fusion welding according to claim 2, characterized in that: In step S51, it specifically includes: S511: The latent heat for melting the plate consumable electrode is calculated from the rated electrode melting rate and the latent heat of melting per unit mass of metal: ； in, Q L is the latent heat used to melt the plate consumable electrode, in W; is the rated electrode melting speed, in kg / s; L is the latent heat of fusion per unit mass of metal, in J / kg; S512: Since the temperature inside the plate-type consumable electrode in the thickness direction is uniformly distributed, the sensible heat inside the plate-type consumable electrode used for heat conduction of the plate-type consumable electrode is: ； in, Q S is the sensible heat used for heat conduction of the plate-type consumable electrode, in W; k m is the thermal conductivity of metal, unit is W / (m·K); l e is the length of the plate consumable electrode, in m; w e is the width of the plate consumable electrode, in m; is the temperature gradient of the plate-type consumable electrode in the height direction, in K / m; S513: According to the heat balance relationship, the heat flux between the slag pool and the plate consumable electrode contact surface is equal to the sum of the latent heat used to melt the plate consumable electrode and the sensible heat used to conduct heat to the plate consumable electrode: ； in, Q s-e is the heat flux between the contact surface of the slag pool and the plate-type consumable electrode, in W; Q L is the latent heat used to melt the plate consumable electrode, in W; Q S is the sensible heat used for heat conduction of the plate-type consumable electrode, in W; S514: The contact area between the slag pool and the plate-type consumable electrode is calculated by Fourier's law: ； in, A s-e The contact area between the slag pool and the plate-type consumable electrode, unit: m 2 ; k l is the liquid phase thermal conductivity of the metal, unit is W / (m·K); T 1 is the slag temperature at the contact surface between the slag pool and the plate-type consumable electrode, unit K; T 2 is the metal solidus temperature, unit K; Q s-e is the heat flux between the contact surface of the slag pool and the plate-type consumable electrode, in W; δ is the thickness of the metal liquid film, in mm; S515: The preset electrode immersion depth is calculated based on the contact area between the slag pool and the plate-type consumable electrode: ； in, h p is the preset electrode immersion depth, in m; A s-e The contact area between the slag pool and the plate-type consumable electrode, unit: m 2 ; l e is the length of the plate consumable electrode, in m; w e It is the width of the plate consumable electrode, in m.

4. The slag filling method for electroslag fusion welding according to claim 1, characterized in that: In step S2, it specifically includes: When the welding current is greater than the rated welding current: ； in, It is the first weight increase caused by the falling of metal droplets due to the melting of the plate consumable electrode per unit time, in kg; The weight gain of the automatic weighing device per unit time, in kg; The weight of slag added per unit time, in kg; According to the first weight increase caused by the metal droplets falling due to the melting of the plate consumable electrode per unit time, , the melting rate of the first electrode is calculated for: ； in, is the melting rate of the first electrode, in kg / s; It is the first weight increase caused by the falling of metal droplets due to the melting of the plate consumable electrode per unit time, in kg; is the unit time, unit s; When the welding current is less than the rated welding current: ； in, The second weight increase per unit time caused by the falling of metal droplets generated by the melting of the plate consumable electrode, unit: kg; The weight gain of the automatic weighing device per unit time, in kg; The weight of slag added per unit time, in kg; The second weight increase caused by the drop of metal droplets produced by the melting of the plate consumable electrode per unit time is , the melting rate of the second electrode is calculated for: ； in, is the melting rate of the second electrode, in kg / s; The second weight increase per unit time caused by the falling of metal droplets generated by the melting of the plate consumable electrode, unit: kg; is the unit time, unit s.

5. The slag filling method for electroslag fusion welding according to claim 1, characterized in that: In step S3, it specifically includes: Comparing the first electrode melting speed or the second electrode melting speed with the rated electrode melting speed, and closing the slag feeder when the first electrode melting speed or the second electrode melting speed is greater than or equal to the rated electrode melting speed; ； in, The third weight increase caused by the falling of metal droplets due to the melting of the plate consumable electrode per unit time, in kg; The weight gain of the automatic weighing device per unit time, in kg; The weight of slag added per unit time, in kg; ； in, is the melting rate of the third electrode, in kg / s; The third weight increase caused by the falling of metal droplets due to the melting of the plate consumable electrode per unit time, in kg; is the unit time, unit s; When the first electrode melting speed or the second electrode melting speed is less than the rated electrode melting speed, the slag feeder is turned on, and the slag feeding speed is calculated from the difference between the first electrode melting speed or the second electrode melting speed and the rated electrode melting speed: ； in, is the electrode melting speed difference, unit is kg / s; is the rated electrode melting speed, in kg / s; is the melting rate of the first electrode, in kg / s; is the melting rate of the second electrode, in kg / s; ； in, The fourth weight increase per unit time is caused by the falling of metal droplets generated by the melting of the plate consumable electrode, in kg; The weight gain of the automatic weighing device per unit time, in kg; The weight of slag added per unit time, in kg; ； in, is the melting rate of the fourth electrode, in kg / s; The fourth weight increase per unit time is caused by the falling of metal droplets generated by the melting of the plate consumable electrode, in kg; is the unit time, unit s.

6. The slag filling method for electroslag fusion welding according to claim 2, characterized in that: In step S52, it specifically includes: S521: Record the total weight gain of the automatic weighing device and the total weight gain of the supplementary slag, and then calculate the total weight gain caused by the falling of the metal droplets generated by the melting of the plate-type consumable electrode; ； in, The total weight gain of the automatic weighing device, in kg; It is the total weight increase caused by the falling of molten metal droplets due to the melting of the plate consumable electrode, in kg; The total weight increase to supplement the slag, in kg; S522: considering the slag density and the metal density, calculating the slag-air interface height increment caused by the total weight increase of the automatic weighing device; ； in, The volume increment caused by the falling of metal droplets and slag filling, unit: m 3 ; It is the total weight increase caused by the falling of molten metal droplets due to the melting of the plate consumable electrode, in kg; The total weight increase to supplement the slag, in kg; ρ m is the metal density, kg / m 3 ; ρ s is the slag density, unit: kg / m 3 ; ； in, The increment of slag-air interface height calculated from the total weight gain of the automatic weighing device, in m; w z is the width of the fusion welding area, in m; l z is the length of the fusion welding area, in m; S523: Since the slag pool height rises due to the plate-type consumable electrode being immersed in the slag pool, the slag-air interface height is corrected by the electrode immersion depth; ； in, The volume of the plate-type consumable electrode immersed in the slag pool, in m 3 ; h p is the preset electrode immersion depth, in m; l e is the length of the plate consumable electrode, in m; w e is the width of the plate consumable electrode, in m; ； in, It is the increment of slag-air interface height caused by the plate-type consumable electrode being immersed in the slag pool, in m; The volume of the plate-type consumable electrode immersed in the slag pool, in m 3 ; w z is the width of the fusion welding area, in m; l z is the length of the fusion welding area, in m; ； in, is the total increment of the slag-air interface height, in m; It is the increment of slag-air interface height caused by the total weight increase of the automatic weighing device, in m; It is the increment of slag-air interface height caused by the plate-type consumable electrode being immersed in the slag pool, in m; Finally, the initial slag-air interface height is calculated from the initial slag volume, the length of the fusion welding area, and the width of the fusion welding area, and the current slag-air interface height is calculated from the total increment of the slag-air interface height; ； in, h a-s_i is the slag-air interface height, in m; m i_s is the initial mass of the slag, in kg; S524: During the electroslag fusion welding process, the welding current will fluctuate. The movement position of the plate consumable electrode changes due to the current fluctuation. The change law of the welding current is as follows: ； in, I is the welding current, unit is A; I r is the rated welding current, in A; ω 0 is the angular frequency determined by the operating frequency of the industrial AC power supply, in Hz; θ 0 is the initial phase of rated welding current; ； in, v e is the actual moving speed of the plate-type consumable electrode, in m / s; v 0 is the average moving speed of the plate-type consumable electrode, in m / s; v v is the fluctuating motion speed of the plate-type consumable electrode, in m / s; ω 1 is the angular frequency of the plate-type consumable electrode movement, in Hz; θ 1 is the initial phase of the plate-type consumable electrode movement, which is determined by the actual working conditions and calculated from the data recorded by the electrode lifting device; ； in, S e_d is the maximum downward movement distance of the plate-type consumable electrode, in m; [t 1 ，t 2 ] The time interval of the downward movement speed of the plate-type consumable electrode, unit: s; v e is the actual moving speed of the plate-type consumable electrode, in m / s; S525: Calculate the maximum metal immersion depth, including the current electrode immersion depth h a-s_i -h e_p , Maximum metal droplet height h d And the maximum downward movement distance of the plate consumable electrode S e_d ; ； in, is the maximum metal immersion depth, in m; h a-s_i -h e_p is the current electrode immersion depth, in m; h e_p is the electrode tip position recorded by the electrode lifting device, in m; h d is the maximum metal droplet height, in m; S e_d is the maximum downward movement distance of the plate-type consumable electrode, in m; ； in, is the maximum metal immersion depth, in m; h p is the preset electrode immersion depth, in m; h d is the maximum metal droplet height, in m; h p + h d ) is the preset maximum metal immersion depth, in m; C is the safety factor; Then, a safety factor is introduced to correct the preset maximum metal immersion depth, and then the maximum metal immersion depth is compared with the preset maximum metal immersion depth.

7. A slag filling device, applied to the slag filling method for electroslag fusion welding as claimed in claim 2, characterized in that: The slag filling device comprises: Automatic weighing device; A fusion welding component is placed above the automatic weighing device; A slag pool, located between the two fusion welding parts; The electrode protection cover is connected to the external support rod to be arranged above the fusion welding component; A slag feeder is arranged below the electrode protection cover and connected to the electrode protection cover, and a slag outlet of the slag feeder faces the slag pool; An electrode lifting device is connected to the external support rod to be arranged above the slag pool; An electrode limiting device is arranged below the electrode lifting device and connected to the electrode lifting device; A plate-type consumable electrode is arranged below the electrode limit device and inserted into the slag pool; The automatic control computer is arranged outside the automatic weighing device and is electrically connected to the automatic weighing device, the electrode protection cover, the slag feeder, the plate-type consumable electrode, the electric limit device, and the electrode lifting device.

8. The slag feeding device according to claim 7, characterized in that: Also includes: The bottom cooling water tank is arranged between the automatic weighing device and the fusion welding component, so as to cool the fusion welding component and the slag pool.

9. The slag feeding device according to claim 7, characterized in that: The number of the slag feeders is multiple.

10. The slag feeding device according to claim 9, characterized in that: A plurality of slag feeders are evenly spaced and arranged in the circumferential direction of the plate-type consumable electrode.

Images