Spheroidizing device for nodular cast iron production

Abstract

The invention relates to the technical field of iron casting production, in particular to a spheroidizing device for nodular cast iron production. Comprising molten iron conveying pipes which are symmetrically arranged, the molten iron conveying pipes penetrate through a ladle and then horizontally point to a valve mechanism arranged in the ladle, molten iron conveyed from the molten iron conveying pipes serves as power to impact the valve mechanism, and the valve mechanism is used for controlling the discharging amount of a spheroidizing agent in a discharging hopper according to the amount of the conveyed molten iron. A nitrogen supplementing mechanism is elastically connected to the upper portion of the valve mechanism, the nitrogen supplementing mechanism communicates with a nitrogen tank and a gas conveying pipe penetrating through the valve mechanism, and the nitrogen supplementing mechanism supplies nitrogen in the nitrogen tank into the gas conveying pipe through vertical movement of the valve mechanism so as to supplement nitrogen lost in the bell jar, and the intensity of the spheroidizing reaction is limited. Molten iron is used for impacting the power plate, so that the valve plate can control the discharging amount of the spheroidizing agent according to the impact force of the molten iron, and the situation that the discharging amount is too large or too small, and the spheroidizing reaction effect is affected is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of iron casting production, in particular to a spheroidizing treatment device for ductile iron production. Background Art

[0002] Ductile iron is made by spheroidizing and inoculating to obtain spheroidal graphite, which effectively improves the mechanical properties of cast iron. Its comprehensive performance is close to that of steel. Based on its excellent performance, it has been successfully used to cast some parts with complex stresses and high requirements for strength, toughness and wear resistance.

[0003] There are many existing technologies for ductile iron casting production equipment, such as: Chinese patent publication number CN113088614B discloses a ductile iron casting production device for improving poor spheroidization, including a spheroidizing bag, a limiting mechanism, an infrared thermometer, a lifting mechanism and a discharging control mechanism. The connecting frame is provided with a group of first temperature measuring holes arranged obliquely, the bracket is provided with a group of second temperature measuring holes with the same inclination angle as the first temperature measuring holes, the upper surface of the bottom end of the bracket is provided with a first limiting groove, the limiting support block is movably mounted on the bracket, the bottom end of the limiting support block is mounted in the first limiting groove, the limiting support block and the bracket are connected by bolts, the temperature measuring probe of the infrared thermometer is mounted inside the second temperature measuring hole, the first temperature measuring hole and the second temperature measuring hole are arranged so that the infrared thermometer can measure the temperature of the molten iron inside the spheroidizing bag, and then accurately understand the temperature of the molten iron, so as to better control the time of adding the ductile inoculant and improve the situation of poor spheroidization.

[0004] It can be seen that in the prior art, in order to improve the effect of cast iron graphite spheroidization, the pre-prepared spheroidizing agent is usually placed in the spheroidizing bag by the flushing method, and then the molten iron is poured into the spheroidizing bag for spheroidization reaction. However, 1. The amount of molten iron in the spheroidizing bag is different each time the spheroidization reaction is carried out, which requires the corresponding spheroidizing agent to be adjusted. The addition of spheroidizing agent is mostly done manually, and the contact of molten iron with external air easily causes oxidation of the molten iron. In addition, manual operation may also cause the spheroidizing agent to be added too much or too little. Excessive addition of spheroidizing agent will reduce the hardness of the ductile iron, thereby causing a decrease in strength and toughness. Insufficient addition of spheroidizing agent will lead to insufficient residual magnesium, thereby affecting the spheroidization effect.

[0005] 2. In the initial stage of the spheroidizing reaction between the spheroidizing agent and molten iron, the chemical reaction is violent, the spheroidizing agent is oxidized in large quantities, the absorption rate of the spheroidizing agent is relatively low, and the amount of smoke released is large, which affects the surrounding environment. Summary of the invention

[0006] The object of the present invention is to provide a spheroidizing treatment device for producing ductile iron to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above-mentioned purpose, the present invention aims to provide a spheroidizing treatment device for ductile iron production, comprising a molten iron ladle, a molten iron delivery pipe, a bell jar and a nitrogen tank, wherein the nitrogen tank is arranged on the upper surface of the bell jar, and a lower hopper is fixed at the bottom of the bell jar, the molten iron delivery pipe is symmetrically arranged, and the molten iron delivery pipe passes through the molten iron ladle and then points horizontally to a valve mechanism arranged inside the molten iron ladle, and the molten iron delivered from the molten iron delivery pipe is used as a power to impact the valve mechanism, and the valve mechanism is used to control the discharge amount of the spheroidizing agent in the lower hopper according to the amount of molten iron delivered, and a nitrogen replenishing mechanism is elastically connected above the valve mechanism, and the nitrogen replenishing mechanism is respectively connected to the nitrogen tank and the gas delivery pipe passing through the valve mechanism, and the nitrogen replenishing mechanism uses the valve mechanism to move up and down to supply the nitrogen in the nitrogen tank into the gas delivery pipe, so as to replenish the nitrogen lost in the bell jar and limit the intensity of the spheroidizing reaction.

[0008] As a further improvement of the technical solution, a partition fixedly connected to the bell jar is provided at the bottom of the lower hopper, and the notches on both sides of the partition are used to accommodate the molten iron delivery pipe, and the partition is sleeved in the ladle, and a gap is left between the outer diameter of the partition and the inner diameter of the ladle, and the gap allows nitrogen to form an airflow in the ladle, thereby limiting the contact between the molten iron and the external air.

[0009] As a further improvement of the present technical solution, the valve mechanism includes power plates symmetrically distributed at the bottom, and the power plates on both sides are combined to form an inverted trapezoid. Each of the power plates starts from the lower end and gradually tilts outward toward the upper end, and the power plates are used to block the molten iron transported by the molten iron conveying pipe, so that the power plates tend to move upward.

[0010] As a further improvement of the present technical solution, the valve mechanism also includes a valve plate with an edge folded upward. Under normal conditions, the folded portion of the valve plate fits with the discharge port of the baffle plate. A sleeve is fixedly connected between the valve plate and the power plate. The power plate, the valve plate and the sleeve are all penetrated by the gas pipe. The power plate is impacted by molten iron to move the valve plate upward to open the discharge port to control the discharge amount of the spheroidizer.

[0011] As a further improvement of the present technical solution, the nitrogen replenishing mechanism includes a reciprocating pull rod whose bottom is fixedly connected to the valve plate, the top of the reciprocating pull rod is sleeved with a gas cylinder that penetrates the bell cover and is fixedly connected to the bell cover, the top of the gas cylinder is connected to the nitrogen tank, and a first one-way valve for supplying nitrogen into the gas cylinder is provided at the connection between the gas cylinder and the nitrogen tank, and an air guide pipe connected to the outside is provided on the gas cylinder near the reciprocating pull rod, and the gas cylinder is connected to the gas pipe.

[0012] As a further improvement of the present technical solution, one end of the gas pipe is connected to a through hole opened on the side wall of the bell jar, and the other end is horizontally flush with the lower edge of the partition, and a second one-way valve is provided in the through hole for nitrogen in the molten iron ladle to enter the gas pipe.

[0013] As a further improvement of the technical solution, a baffle plate flush with the bottom of the gas cylinder is fixedly connected to the gas pipe, a tension spring is elastically connected between the bottom of the baffle plate and the valve plate, and the tension spring is sleeved on the gas pipe. Under normal conditions, the tension spring is in a stretched state.

[0014] As a further improvement of the technical solution, an opening and closing device for diffusing the spheroidizing agent is arranged at the bottom of the discharge hopper, wherein the opening and closing device includes an outer discharge plate whose outer edge is in contact with the inner wall of the bell jar, and an inner discharge plate located below the outer discharge plate and in contact with the outer discharge plate, the outer edge of the inner discharge plate is fixedly connected to the inner wall of the bell jar, and a plurality of discharge holes are provided on the outer discharge plate and the inner discharge plate, and under normal conditions, the discharge holes on the outer discharge plate and the inner discharge plate are in a staggered state.

[0015] As a further improvement of the present technical solution, an outer ring is coaxially connected to the top of the outer blanking plate, a wedge block is fixedly connected to the inner wall of the outer ring, the wedge block abuts against a protrusion fixed to the bottom of the valve plate, an inner ring fixedly connected to the top of the inner blanking plate is provided on the inner ring of the outer ring, a return spring is elastically connected between the inner ring and the wedge block, so that when the protrusion is detached from the wedge block, the elastic potential energy is used to make the blanking holes on the outer blanking plate overlap with those on the inner blanking plate.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. In the spheroidizing treatment device for ductile iron production, molten iron is used to impact the power plate, so that the valve plate can control the feeding amount of the spheroidizing agent according to the impact force of the molten iron, avoiding excessive or insufficient feeding amount, which affects the effect of the spheroidizing reaction.

[0017] 2. In the spheroidizing treatment device for producing ductile iron, a reciprocating pull rod is used to pressurize the nitrogen from the gas cylinder into the molten iron ladle. When the molten iron reacts with the spheroidizing agent, there is a continuous flow of nitrogen gas in the gap between the partition and the inner wall of the molten iron ladle, which can effectively prevent the molten iron from reacting with oxygen in the air and avoid oxidation of the molten iron. The molten iron under the protection of nitrogen is more likely to form a stable spheroidal graphite structure, thereby improving the quality and performance of the spheroidized molten iron and reducing the generation of smoke. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 It is a schematic diagram of the explosion structure of the ladle and bell jar of the present invention; Figure 3It is a left view of the cutaway internal structure of the iron ladle and bell jar of the present invention; Figure 4 It is a front view of the internal structure of the bell jar of the present invention; Figure 5 It is a schematic diagram of the cross-section structure of the gas delivery pipe, valve mechanism, and gas delivery cylinder of the present invention; Figure 6 It is a top view of the outer blanking plate structure of the present invention; Figure 7 For the present invention Figure 6 A is an enlarged structural diagram; Figure 8 It is a schematic diagram of the explosion structure of the valve plate, the outer blanking plate, the inner blanking plate and the power plate of the present invention.

[0019] The meaning of each number in the figure is: 100, molten iron ladle; 101, molten iron conveying pipe; 110, bell jar; 111, nitrogen tank; 112, partition; 113, lower hopper; 120, valve mechanism; 121, power plate; 122, valve plate; 123, sleeve; 124, bump; 130. Nitrogen replenishing mechanism; 131. Reciprocating pull rod; 132. Gas cylinder; 133. Baffle; 140. Gas pipeline; 150. Extension spring; 160, outer blanking plate; 161, outer sleeve ring; 162, wedge block; 170. Inner blanking plate; 171. Inner sleeve ring; 172. Return spring. DETAILED DESCRIPTION

[0020] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0022] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0023] like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, a spheroidizing treatment device for ductile iron production is provided, including a molten iron ladle 100, a molten iron delivery pipe 101, a bell jar 110 and a nitrogen tank 111, wherein the nitrogen tank 111 is arranged on the upper surface of the bell jar 110, a lower hopper 113 is fixed at the bottom of the bell jar 110, and the molten iron delivery pipe 101 is symmetrically arranged. The molten iron delivery pipe 101 penetrates the molten iron ladle 100 and then points horizontally to a valve mechanism 120 arranged inside the molten iron ladle 100. The molten iron delivered from the molten iron delivery pipe 101 is used as a power to operate the valve mechanism 120. The valve mechanism 120 is used to control the discharge amount of the spheroidizing agent in the discharge hopper 113 according to the amount of molten iron transported. A nitrogen replenishing mechanism 130 is elastically connected above the valve mechanism 120. The nitrogen replenishing mechanism 130 is respectively connected to a nitrogen tank 111 and an air pipe 140 passing through the valve mechanism 120. The nitrogen replenishing mechanism 130 utilizes the valve mechanism 120 to move up and down to supply the nitrogen in the nitrogen tank 111 into the air pipe 140, so as to replenish the nitrogen lost in the bell jar 110 and limit the severity of the spheroidizing reaction.

[0024] First, after the bell jar 110 and the molten iron ladle 100 are matched, the spheroidizing agent is added to the lower hopper 113 through the feed port on the bell jar 110. Secondly, in order to prevent the molten iron from contacting the external air and improve the quality and performance of the spheroidized molten iron, a partition 112 fixedly connected to the bell jar 110 is provided at the bottom of the lower hopper 113. The notches on both sides of the partition 112 are used to accommodate the molten iron conveying pipe 101, and the partition 112 is sleeved in the molten iron ladle 100. A gap is left between the outer diameter of the partition 112 and the inner diameter of the ladle 100. The gap allows nitrogen to form an airflow in the ladle 100, limiting the contact between the molten iron and the external air. The molten iron under the protection of nitrogen is easier to form a stable spheroidal graphite structure, thereby improving the quality and performance of the spheroidized molten iron.

[0025] The valve mechanism 120 under normal conditions can limit the descent of the spheroidizing agent in the lower hopper 113. Figure 4 Based on and combined with Figure 5As shown, the specific structure of the valve mechanism 120 is disclosed. The valve mechanism 120 includes a power plate 121 with a symmetrical distribution at the bottom. The power plates 121 on both sides are surrounded to form an inverted trapezoid. Each power plate 121 starts from the lower end and gradually tilts outward toward the upper end. The power plate 121 is used to block the molten iron transported by the molten iron transport pipe 101, so that the power plate 121 has a tendency to move upward. On the other hand, the valve mechanism 120 also includes a valve plate 122 with an edge folded upward. Under normal conditions, the folded portion of the valve plate 122 fits the discharge port of the baffle 133, and the discharge port is blocked. A sleeve 123 is fixedly connected between the valve plate 122 and the power plate 121. The power plate 121, the valve plate 122 and the sleeve 123 are all penetrated by the gas pipe 140. The molten iron is used to impact the power plate 121, so that the valve plate 122 moves upward to open the discharge port to control the discharge amount of the spheroidizing agent.

[0026] Regarding the impact force generated by the molten iron on the power plate 121 , according to the decomposition of the force, it can be known that the impact force of the molten iron will generate a component force that causes the power plate 121 to move upward, and this component force will cause the power plate 121 to tend to move upward.

[0027] In addition, molten iron usually flows out from a blast furnace or other smelting equipment. The molten iron will be affected by various factors during the outflow process, such as changes in furnace temperature, mixing of slag, and pipe blockage, which will cause discontinuity in the flow of molten iron. Therefore, when the molten iron flows out from the power plate 121, the impact force on the power plate 121 is not constant.

[0028] In this way, when the impact force of the molten iron increases, the opening of the discharge port of the discharge hopper 113 increases, and the discharge amount of the spheroidizing agent increases. On the contrary, when the impact force of the molten iron weakens, the opening of the discharge port decreases, and the discharge amount of the spheroidizing agent decreases. In this way, the discharge amount of the spheroidizing agent can be controlled according to the impact force of the molten iron to avoid excessive or insufficient discharge, which affects the effect of the spheroidizing reaction.

[0029] Furthermore, as the molten iron in the ladle 100 gradually increases, the nitrogen content in the ladle 100 decreases. As mentioned above, the nitrogen replenishing mechanism 130 is used to replenish nitrogen into the bell jar 110 to suppress the severity of the spheroidization reaction. The specific structure of the nitrogen replenishing mechanism 130 is publicly described below. The nitrogen replenishing mechanism 130 includes a reciprocating rod 131 whose bottom is fixedly connected to the valve plate 122, and the top of the reciprocating rod 131 is sleeved with a gas cylinder 132 that penetrates the bell jar 110 and is fixedly connected to the bell jar 110. The top of the gas cylinder 132 is connected to the nitrogen tank 111, and a first one-way valve for supplying nitrogen to the gas cylinder 132 is provided at the connection between the gas cylinder 132 and the nitrogen tank 111. An air guide pipe connected to the outside is provided on the gas cylinder 132 near the reciprocating rod 131, and the gas cylinder 132 is connected to the gas pipe 140.

[0030] The process of replenishing the nitrogen in the nitrogen tank 111 into the molten iron ladle 100 is divided into two processes, and the specific working principle is shown as follows: In the first stage, when the valve plate 122 moves upward, the first one-way valve is in a closed state, and external air is drawn in from the air duct. The reciprocating pull rod 131 presses the nitrogen previously drawn in from the air cylinder 132 into the air pipe 140 through the air cylinder 132. One end of the air pipe 140 is connected to a through hole opened on the side wall of the bell jar 110, and the other end is horizontally flush with the lower edge of the partition 112. A second one-way valve is provided in the through hole for the nitrogen in the molten iron ladle 100 to enter the air pipe 140. Therefore, the nitrogen transported from the air cylinder 132 to the air pipe 140 will be transported into the molten iron ladle 100, so that when the molten iron reacts with the spheroidizing agent, there is a continuous flow of nitrogen gas in the gap between the partition 112 and the inner wall of the molten iron ladle 100. Moreover, nitrogen is an inert gas and is not easy to react chemically with other substances. Therefore, when nitrogen is evenly distributed in the ladle 100, it can effectively prevent the molten iron from reacting with oxygen in the air and avoid oxidation of the molten iron. The molten iron under the protection of nitrogen is more likely to form a stable spheroidal graphite structure, thereby improving the quality and performance of the spheroidized molten iron and reducing the generation of smoke.

[0031] In the second stage, when the valve plate 122 moves downward, the first one-way valve opens, the nitrogen in the nitrogen tank 111 is drawn into the gas cylinder 132, and the air in the gas cylinder 132 is discharged from the air duct. This process is the preparation stage of the first stage.

[0032] It is worth noting that the maximum displacement of the top of the reciprocating rod 131 is lower than the connection between the gas cylinder 132 and the gas pipe 140 in the horizontal direction to prevent the reciprocating rod 131 from moving excessively in the reverse direction and sucking the nitrogen in the molten iron ladle 100 into the gas pipe 140.

[0033] Considering that the nitrogen in the nitrogen tank 111 can only be drawn into the gas cylinder 132 by relying on gravity, a baffle 133 flush with the bottom of the gas cylinder 132 is fixedly connected to the gas pipe 140, and a tension spring 150 is elastically connected between the bottom of the baffle 133 and the valve plate 122. The tension spring 150 is sleeved on the gas pipe 140. Under normal circumstances, the tension spring 150 is in a tensioned state, that is, when the valve plate 122 moves upward, the molten iron overcomes gravity and elastic potential energy to push the power plate 121 upward. When the valve plate 122 moves from top to bottom, the tension spring 150 uses its own elastic potential energy to push the valve plate 122 downward in the opposite direction, thereby drawing the nitrogen in the nitrogen tank 111 into the gas cylinder 132 through the reciprocating pull rod 131 for use.

[0034] In addition, when the spheroidizing agent in the lower hopper 113 falls, in order to make the spheroidizing agent evenly scattered in the molten iron and react with the molten iron, it returns to Figure 4 , Figure 5 Combined with Figure 6 , Figure 7 and Figure 8 As shown, an opening and closing device for diffusing the spheroidizing agent is provided at the bottom of the discharge hopper 113, wherein the opening and closing device includes an outer discharge plate 160 whose outer edge is in contact with the inner wall of the bell jar 110, and an inner discharge plate 170 located below the outer discharge plate 160 and in contact with the outer discharge plate 160, the outer edge of the inner discharge plate 170 is fixedly connected to the inner wall of the bell jar 110, and a plurality of discharge holes are provided on the outer discharge plate 160 and the inner discharge plate 170, and under normal conditions, the discharge holes on the outer discharge plate 160 and the inner discharge plate 170 are in a staggered state. On the other hand, an outer ring 161 is coaxially connected to the top of the outer blanking plate 160, and a wedge block 162 is fixedly connected to the inner wall of the outer ring 161. The wedge block 162 abuts against the protrusion 124 fixed on the bottom of the valve plate 122. An inner ring 171 fixedly connected to the top of the inner blanking plate 170 is provided on the inner circle of the outer ring 161. A return spring 172 is elastically connected between the inner ring 171 and the wedge block 162, so that when the protrusion 124 is separated from the wedge block 162, the elastic potential energy is used to make the blanking holes on the outer blanking plate 160 and the inner blanking plate 170 overlap.

[0035] In specific operation, when the valve plate 122 moves upward, the spheroidizer in the hopper 113 falls onto the outer feed plate 160. At the same time, the protrusion 124 breaks away from the restriction on the wedge block 162, so that the outer feed plate 160 rotates counterclockwise under the elastic action of the inner ring 171 (refer to Figure 7 As shown in the figure, the discharge holes on the outer discharge plate 160 and the inner discharge plate 170 are offset and overlapped, specifically according to the distance that the valve plate 122 moves upward. During this process, the spheroidizer rolls from the top of the outer discharge plate 160 to the outer edge, and is evenly scattered in the molten iron through the discharge holes, which is beneficial to the formation and uniform distribution of graphite balls. On the contrary, when the molten iron stops being injected, the protrusion 124 moves downward to squeeze the wedge block 162, causing the wedge block 162 to rotate clockwise to compress the return spring 172.

[0036] Furthermore, in specific use, the distance between the feed holes can be reduced to reduce the accumulation of the spheroidizing agent on the outer edge of the outer feed plate 160 .

[0037] Secondly, when the feeding hole is blocked, as the outer feeding plate 160 rotates, the feeding holes on the outer feeding plate 160 and the inner feeding plate 170 gradually shift and overlap. Since the speed of the nitrogen discharged from the ladle 100 is low, the temperature and pressure in the ladle 100 and the bell jar 110 are high, the nitrogen introduced into the ladle 100 from the gas pipe 140 also has the function of backblowing to clear the feeding hole. Moreover, the nitrogen passing through the inner feeding plate 170 and the outer feeding plate 160 will also clear the feeding port of the feeding hopper 113 in reverse. Part of the nitrogen circulates into the ladle 100 under the guidance of the gas pipe 140, thereby reducing the waste of nitrogen.

[0038] Finally, when the spheroidization reaction is completed, the bell jar 110 is lifted and the gas pipe 140 is cleaned to prevent the residual molten iron from clogging the gas pipe 140.

[0039] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and descriptions are only preferred examples of the present invention and are not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A spheroidizing treatment device for ductile iron production, characterized in that: The invention comprises a molten iron ladle (100), a molten iron delivery pipe (101), a bell (110), and a nitrogen tank (111), wherein the nitrogen tank (111) is arranged on the upper surface of the bell (110), a lower hopper (113) is fixed on the bottom of the bell (110), the molten iron delivery pipe (101) is symmetrically arranged, and the molten iron delivery pipe (101) passes through the molten iron ladle (100) and then points horizontally to a valve mechanism (120) arranged inside the molten iron ladle (100), and the molten iron delivered from the molten iron delivery pipe (101) is used as a power to impact the valve mechanism (120). (120) is used to control the discharge amount of the spheroidizing agent in the discharge hopper (113) according to the amount of molten iron being transported. A nitrogen replenishing mechanism (130) is elastically connected above the valve mechanism (120). The nitrogen replenishing mechanism (130) is respectively connected to a nitrogen tank (111) and an air supply pipe (140) passing through the valve mechanism (120). The nitrogen replenishing mechanism (130) uses the valve mechanism (120) to move up and down to supply the nitrogen in the nitrogen tank (111) into the air supply pipe (140) to replenish the nitrogen lost in the bell jar (110) and limit the intensity of the spheroidizing reaction.

2. The spheroidizing treatment device for ductile iron production according to claim 1, characterized in that: A partition (112) fixedly connected to the bell (110) is provided at the bottom of the lower hopper (113), and the notches on both sides of the partition (112) are used to accommodate the molten iron conveying pipe (101), and the partition (112) is sleeved in the molten iron ladle (100), and a gap is left between the outer diameter of the partition (112) and the inner diameter of the molten iron ladle (100), and the gap allows nitrogen to form an airflow in the molten iron ladle (100), thereby limiting the contact between the molten iron and the external air.

3. The spheroidizing treatment device for ductile iron production according to claim 1, characterized in that: The valve mechanism (120) comprises power plates (121) symmetrically distributed at the bottom, the power plates (121) on both sides enclose each other to form an inverted trapezoid, each power plate (121) gradually tilts outwards from the bottom end toward the top end, and the power plates (121) are used to block the molten iron transported by the molten iron transport pipe (101), so that the power plates (121) tend to move upwards.

4. The spheroidizing treatment device for ductile iron production according to claim 3, characterized in that: The valve mechanism (120) further comprises a valve plate (122) with an edge folded upwards. The nitrogen replenishing mechanism (130) comprises a reciprocating pull rod (131) whose bottom is fixedly connected to the valve plate (122). The top of the reciprocating pull rod (131) is sleeved with a gas cylinder (132) that penetrates the bell housing (110) and is fixedly connected to the bell housing (110). The top of the gas cylinder (132) is connected to the nitrogen tank (111). A first one-way valve for supplying nitrogen to the gas cylinder (132) is provided at the connection between the gas cylinder (132) and the nitrogen tank (111). An air guide pipe that is connected to the outside is provided on the gas cylinder (132) near the reciprocating pull rod (131). The gas cylinder (132) is connected to the gas pipe (140).

5. The spheroidizing treatment device for ductile iron production according to claim 4, characterized in that: A baffle (133) flush with the bottom of the gas cylinder (132) is fixedly connected to the gas delivery pipe (140); in a normal state, the folded portion of the valve plate (122) fits with the discharge port of the baffle (133); a sleeve (123) is fixedly connected between the valve plate (122) and the power plate (121); the power plate (121), the valve plate (122) and the sleeve (123) are all penetrated by the gas delivery pipe (140); molten iron is used to impact the power plate (121) so that the valve plate (122) moves upward to open the discharge port to control the discharge amount of the spheroidizing agent.

6. The spheroidizing treatment device for ductile iron production according to claim 2, characterized in that: One end of the gas delivery pipe (140) is communicated with a through hole provided on the side wall of the bell jar (110), and the other end is aligned with the lower edge of the partition (112) in the horizontal direction. A second one-way valve is provided in the through hole for nitrogen in the iron ladle (100) to enter the gas delivery pipe (140).

7. The spheroidizing treatment device for ductile iron production according to claim 5, characterized in that: A tension spring (150) is elastically connected between the bottom of the baffle (133) and the valve plate (122); the tension spring (150) is sleeved on the gas delivery pipe (140); and under normal conditions, the tension spring (150) is in a tensioned state.

8. The spheroidizing treatment device for ductile iron production according to claim 5, characterized in that: An opening and closing device for diffusing the spheroidizing agent is provided at the bottom of the discharge hopper (113), wherein the opening and closing device comprises an outer discharge plate (160) whose outer edge is in contact with the inner wall of the bell jar (110), and an inner discharge plate (170) located below the outer discharge plate (160) and in contact with the outer discharge plate (160), wherein the outer edge of the inner discharge plate (170) is fixedly connected to the inner wall of the bell jar (110), and a plurality of discharge holes are provided on the outer discharge plate (160) and the inner discharge plate (170), and under normal conditions, the discharge holes on the outer discharge plate (160) and the inner discharge plate (170) are in a dislocated state.

9. The spheroidizing treatment device for ductile iron production according to claim 8, characterized in that: An outer sleeve (161) is coaxially connected to the top of the outer blanking plate (160), and a wedge block (162) is fixedly connected to the inner wall of the outer sleeve (161). The wedge block (162) abuts against a protrusion (124) fixed to the bottom of the valve plate (122). An inner sleeve (171) fixedly connected to the top of the inner blanking plate (170) is provided on the inner ring of the outer sleeve (161). A return spring (172) is elastically connected between the inner sleeve (171) and the wedge block (162), so that when the protrusion (124) and the wedge block (162) are separated, the elastic potential energy is used to make the blanking holes on the outer blanking plate (160) and the inner blanking plate (170) overlap.

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