CN112626408A

CN112626408A - Method for producing switch tie and switch tie

Info

Publication number: CN112626408A
Application number: CN202011355687.2A
Authority: CN
Inventors: 何文超; 郑鑫; 刘恒亮; 杜文举; 杨顺强; 何早能
Original assignee: China Railway Construction Heavy Industry Group Co Ltd
Current assignee: China Railway Construction Heavy Industry Group Co Ltd
Priority date: 2020-11-27
Filing date: 2020-11-27
Publication date: 2021-04-09
Anticipated expiration: 2040-11-27
Also published as: CN112626408B

Abstract

The invention provides a switch tie and a production method thereof. The production method of the turnout sleeper comprises a smelting process, a molding process and a heat treatment process, wherein the smelting process comprises an oxidation method, and the oxidation method comprises diffusion deoxidation, precipitation deoxidation and final deoxidation which are sequentially carried out. Through the technical scheme of the invention, the defects of air holes, shrinkage cavities and the like in the switch tie are effectively reduced, the rigidity and the strength of the switch tie are improved, the service life of the switch tie is prolonged, and the switch tie is simple in structure and easy to produce.

Description

Method for producing switch tie and switch tie

Technical Field

The invention relates to the technical field of rail transit, in particular to a switch tie and a production method thereof.

Background

A switch is a line connection device for a rolling stock to switch from one track to another and is one of the weak links of a track. The precision of switch equipment directly influences the atress, the ride comfort of track structure, driving safety and travelling comfort. The turnout assembling is a key process for ensuring the turnout laying precision.

The switch tie for assembling is one of special tools for assembling the switch. The switch tie that present switch equipment used generally is tray fixed concrete type, and concrete switch tie can all be very convenient adjusts in three directions, nevertheless along with the promotion of quality requirement, exposes gradually that the adjustment volume is uncontrolled, the plane can't keep, some shortcomings such as rigidity is not enough. The cast steel switch tie is adopted to replace the original concrete switch tie, and the steel switch tie is integrally formed, so that the overall rigidity is high, and the defects are avoided.

However, the prior experience is not used for reference in the preparation of the cast steel switch tie for switch assembly at present, and in order to ensure the strength and the rigidity of the switch tie, the thickness of the wall of the cast steel switch tie is thicker, so whether the casting defects of air holes, sand inclusion, shrinkage cavities and the like existing in a casting can be effectively overcome, and the service condition and the service life of the cast steel switch tie are directly influenced.

Disclosure of Invention

Embodiments according to the present invention are directed to improving at least one of the technical problems of the related art or the related art.

In view of the above, an object according to an embodiment of the present invention is to provide a method for producing a switch tie.

It is another object of an embodiment according to the present invention to provide a switch tie.

In order to achieve the above object, an embodiment according to a first aspect of the present invention provides a method for producing a switch tie, comprising a smelting process, a molding process and a heat treatment process, wherein the smelting process comprises an oxidation method,

wherein, the oxidation method comprises diffusion deoxidation, precipitation deoxidation and final deoxidation which are carried out in sequence.

In the technical scheme, the oxidation method comprises diffusion deoxidation, precipitation deoxidation and final deoxidation which are sequentially carried out, namely, a plurality of deoxidation modes are combined, and the deoxidation in various aspects is carried out for a plurality of times. The combined deoxidation mode is beneficial to better eliminating the defects of air holes in the casting process, namely the air holes in the switch tie can be reduced, the strength and the rigidity of the switch tie are improved, and the service life of the switch tie is prolonged.

In the technical scheme, the smelting process comprises the following steps: charging in an electric furnace: adding lime, iron ore and fluorite into the electric furnace, and simultaneously adding waste steel into the charging bucket; oxidation dephosphorization and decarbonization: adding limestone and fluorite into an electric furnace, blowing oxygen after furnace slag is formed, drawing out oxidation slag after oxidation is finished, adding lime and fluorite, and slagging; pre-reduction: after the slag is formed, adding carbon powder, silicon carbide and silicon-manganese alloy into the electric furnace for diffusion deoxidation; reduction: adding carbon powder, silicon carbide, high-carbon ferromanganese and ferrosilicon alloy into an electric furnace, and performing precipitation deoxidation; tapping: tapping at 1500-1800 deg.c, adding Si-Ba-Ca and Al ingot into the ladle and final deoxidizing.

In the technical scheme, lime, iron ore and fluorite are added when the electric furnace is charged, so that slagging at the bottom of the furnace is facilitated. Through oxidation dephosphorization and decarbonization, the content of impurities such as phosphorus, carbon and the like is reduced conveniently, the toughness and the strength of the formed switch tie are improved, and the service life of the switch tie is prolonged. Through diffusion deoxidation, precipitation deoxidation and final deoxidation, namely, multiple times of deoxidation in various aspects, the reduction of air holes in the turnout sleeper is facilitated, and the strength and the rigidity of the turnout sleeper are improved.

In the technical scheme, in the smelting process, the total amount of the added raw materials and the percentage requirement of the steel are as follows: 2 to 3 percent of lime, 1.5 to 2 percent of iron ore, 0.7 to 1 percent of fluorite, 90 to 95 percent of scrap steel, 0.3 to 0.4 percent of carbon powder, 0.3 to 0.4 percent of silicon carbide, 0.5 to 0.6 percent of manganese-silicon alloy, 0.12 to 0.15 percent of aluminum ingot and 0.15 to 0.2 percent of calcium silicon-barium; additionally, the oxygen pressure is 0.5MPa to 0.8 MPa.

In the technical scheme, the requirement of the total amount of the raw materials is limited, so that the raw materials can be prevented from being added randomly, and the smelting effect is ensured.

In the technical scheme, in the pre-reduction process, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 0.1 to 0.15 percent of carbon powder, 0.1 to 0.15 percent of silicon carbide and 0.5 to 0.6 percent of silicon-manganese alloy; in the reduction process, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 0.2 to 0.25 percent of carbon powder, 0.15 to 0.25 percent of silicon carbide, 0.6 to 1 percent of high-carbon ferromanganese and 0.4 to 0.6 percent of ferrosilicon; in the tapping process, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 0.15 to 0.2 percent of silicon-barium-calcium and 0.12 to 0.15 percent of aluminum ingot.

In the technical scheme, the quantity of the added raw materials is independently limited in each step of the smelting process, so that the quantity of the raw materials in each step can not be added randomly, and the treatment effect of each step is ensured. In addition, the quantity of the raw materials in each step is limited, so that the total quantity of the raw materials added in each step is ensured to meet the requirement, and the condition that the quantity of the raw materials in a single step is excessively added to cause the quantity of the raw materials in other steps to be reduced and the treatment effect of the other steps is influenced is avoided.

In the technical scheme, when the electric furnace is charged, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 2 to 3 percent of lime, 1.5 to 2 percent of iron ore and 0.7 to 1 percent of fluorite; the steel scraps comprise large steel scraps, medium steel scraps and small steel scraps, wherein the steel scraps, the medium steel scraps and the small steel scraps are as follows, the weight ratio is 0.8-1.2: 2-4: loading in a weight ratio of 0.8-1.2; when dephosphorization and decarbonization are carried out by oxidation, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 2 to 3 percent of lime and 0.7 to 1 percent of fluorite; when the oxidation slag is completely pulled out after the oxidation is finished, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 2 to 3 percent of lime and 0.7 to 1 percent of fluorite.

In the technical scheme, the quantity of the added raw materials is independently limited in each step of the smelting process, so that the quantity of the raw materials in each step can not be added randomly, and the treatment effect of each step is ensured. In addition, the quantity of the raw materials in each step is limited, so that the total quantity of the raw materials added in each step is ensured to meet the requirement, and the condition that the quantity of the raw materials in a single step is excessively added to cause the quantity of the raw materials in other steps to be reduced and the treatment effect of the other steps is influenced is avoided. The proportion of large scrap steel, medium scrap steel and small scrap steel is limited, full utilization of various scrap steels with different specifications is facilitated, and the utilization rate of the scrap steel is improved.

It should be noted that the large scrap blocks weigh more than 50kg and not more than 200kg, the medium scrap blocks weigh more than 10kg and not more than 50kg, and the small scrap blocks weigh not more than 10 kg.

In the above technical solution, the oxygen blowing specifically comprises: the oxygen lance is inserted 50 mm-200 mm below the liquid level of the steel, shallow blowing is carried out for 2 min-4 min, and the oxygen blowing pressure is 0.5 MPa-0.8 MPa; after shallow blowing is finished, the oxygen lance is inclined by 20-30 degrees, and is inserted into the position 150-300 mm below the liquid level of steel, and the molten pool is kept to be uniformly boiled until the weight percentage content of phosphorus, carbon and manganese in the molten pool is less than or equal to 0.006%, 0.21% and 0.23%, respectively.

In the technical scheme, the oxygen blowing time, the oxygen blowing depth and the oxygen blowing pressure are limited, so that the oxygen blowing effectiveness is improved, and the oxygen blowing inefficiency caused by too short oxygen blowing time and too shallow oxygen blowing depth is avoided. And the method is also favorable for accelerating the oxidation process and improving the smelting efficiency.

In any one of the above technical schemes, the molding process comprises casting feeding, riser setting, chill setting and inclined pouring.

In the technical scheme, the casting feeding is carried out in the molding process, so that the shrinkage phenomenon in the switch tie is reduced conveniently. The arrangement of the dead head is convenient for supplementing metal solution, and further reduces the occurrence of shrinkage cavity phenomenon. By arranging the chilling blocks, the switch tie is conveniently chilled, and the defect of shrinkage cavity is reduced. The inclined casting mode is favorable for improving the fluidity of the metal liquid, and further the shrinkage cavity phenomenon can be reduced.

In the technical scheme, the casting feeding proportion is 1-3%; the riser is arranged at the pouring end of the switch tie and is positioned at the rib plate of the switch tie; the chills are arranged on the top of the switch tie and the ear plates and are bright chills; the inclination angle of the inclined pouring is 6-8 degrees; in the molding process, the draft angle is 1: 20.

In the technical scheme, the casting feeding proportion is limited in a certain range, so that shrinkage cavities can be reduced, and material waste caused by overlarge proportion can be avoided. The riser is arranged at the pouring end of the switch tie, namely the riser is arranged at a higher position during pouring, so that supplemented metal solution can flow to a lower position conveniently, and the effect of preventing shrinkage cavity is ensured. The inclination angle of the inclined pouring is limited to 6-8 degrees, so that the fluidity of the metal liquid can be improved, and the over-high flow speed of the metal solution can be avoided. The draft is set to 1: and 20, the smoothness of the die drawing is convenient to improve.

In the technical scheme, the heat treatment process is normalizing, the heat preservation temperature of the normalizing is 800-1000 ℃, and the heat preservation time of the normalizing is 2-4 hours.

In the technical scheme, through adopting the normalizing treatment, the toughness of the switch tie is favorably improved, and the service life of the switch tie is prolonged.

An embodiment according to a second aspect of the present invention provides a switch tie, including: the device comprises a top plate and vertical plates, wherein the vertical plates are arranged on two sides of the top plate respectively, and an included angle is formed between each vertical plate and the top plate; the end of each vertical plate far away from the top plate is provided with an ear plate; the plurality of rib plates are arranged between the two vertical plates at intervals; the switch tie is integrally cast and molded by adopting the production method of the switch tie in any one of the above technical schemes of the first aspect.

In this technical scheme, the switch tie is integrally cast and molded by the method for producing the switch tie according to any one of the above technical schemes, so that all the beneficial effects of the above technical scheme are achieved, and further description is omitted here. The switch tie produced by the technical scheme reduces the defects of air holes, shrinkage cavities and the like, and has the advantages of higher strength and rigidity, good toughness and long service life. In addition, the switch tie adopts the arrangement of the top plate, the vertical plate, the ear plate and the rib plate, the structure is simple, all parts are integrally formed, the rigidity is good, and the switch tie is not easy to deform during assembly.

Additional aspects and advantages of embodiments in accordance with the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of embodiments in accordance with the invention.

Drawings

Figure 1 is a schematic illustration of a cast construction of a switch tie according to one embodiment of the present invention;

FIG. 2 is a schematic sectional view taken along the line A-A in FIG. 1;

FIG. 3 is a schematic cross-sectional view taken along the line B-B in FIG. 1;

figure 4 is a cross-sectional structural schematic of a switch tie according to one embodiment provided herein;

figure 5 is a schematic diagram of a heat treatment process for a switch tie in accordance with one embodiment of the present invention.

Wherein, the correspondence between the reference numbers and the part names in fig. 1 to 4 is:

10 switch ties, 100 first chills, 102 non-casting end faces, 104 rib plates, 106 risers, 108 casting end faces, 110 casting systems, 112 top plates, 114 second chills, 116 ear plates and 118 vertical plates.

Detailed Description

In order that the above objects, features and advantages of embodiments in accordance with the present invention may be more clearly understood, embodiments in accordance with the present invention are described in further detail below with reference to the accompanying drawings and the detailed description. It should be noted that features of embodiments according to the invention may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments according to the invention, however, embodiments according to the invention may be practiced in other ways than those described herein, and therefore, embodiments according to the invention are not limited in scope by the specific embodiments disclosed below.

Some embodiments provided according to the present invention are described below with reference to fig. 1 to 5.

As shown in fig. 1 to 5, an embodiment according to a first aspect of the present invention provides a method for producing a switch tie, which includes a smelting process, a molding process and a heat treatment process. The smelting process comprises an oxidation method. Wherein, the oxidation method comprises diffusion deoxidation, precipitation deoxidation and final deoxidation which are carried out in sequence.

In this embodiment, the oxidation method includes diffusion deoxidation, precipitation deoxidation and final deoxidation which are performed sequentially, that is, a combination of a plurality of deoxidation modes, and a plurality of multifaceted deoxidation. The combined deoxidation mode is beneficial to better eliminating the defects of air holes in the casting process, namely the air holes in the switch tie can be reduced, the strength and the rigidity of the switch tie are improved, and the service life of the switch tie is prolonged.

In the embodiment, the smelting process sequentially comprises circuit charging, oxidation dephosphorization decarburization, pre-reduction, reduction and steel tapping. Specifically, electric furnace charging: adding lime, iron ore and fluorite into the electric furnace, and simultaneously adding waste steel into the charging bucket. Oxidation dephosphorization and decarbonization: adding limestone and fluorite into the electric furnace, blowing oxygen after the slag is formed, drawing out the oxidized slag after the oxidation is finished, and adding lime and fluorite for slagging. Pre-reduction: after the slag is formed, carbon powder, silicon carbide and silicon-manganese alloy are added into the electric furnace for diffusion deoxidation. Reduction: adding carbon powder, silicon carbide, high-carbon ferromanganese and ferrosilicon alloy into an electric furnace, and performing precipitation deoxidation. Tapping: tapping at 1500-1800 deg.c, adding Si-Ba-Ca and Al ingot into the ladle and final deoxidizing.

In this embodiment, the bottom slagging is facilitated by adding lime, iron ore and fluorite at the time of charging the electric furnace. Through oxidation dephosphorization and decarbonization, the content of impurities such as phosphorus, carbon and the like is reduced conveniently, the toughness and the strength of the formed switch tie are improved, and the service life of the switch tie is prolonged. Through diffusion deoxidation, precipitation deoxidation and final deoxidation, namely, multiple times of deoxidation in various aspects, the reduction of air holes in the turnout sleeper is facilitated, and the strength and the rigidity of the turnout sleeper are improved.

In the above embodiment, in the smelting process, the total amount of the added raw materials and the percentage of the steel are as follows: 2 to 3 percent of lime, 1.5 to 2 percent of iron ore, 0.7 to 1 percent of fluorite, 0.3 to 0.4 percent of carbon powder, 0.3 to 0.4 percent of silicon carbide, 0.5 to 0.6 percent of manganese-silicon alloy, 0.12 to 0.15 percent of aluminum ingot, 0.15 to 0.2 percent of calcium barium silicate and 90 to 95 percent of scrap steel; additionally, the oxygen pressure is 0.5MPa to 0.8 MPa.

It is understood that the percentage requirements of the above quantities can also be understood as the following requirements: 20kg/t steel-30 kg/t steel of lime, 15kg/t steel-20 kg/t steel of iron ore, 7kg/t steel-10 kg/t steel of fluorite, 0.5 MPa-0.8 MPa of oxygen pressure, 3kg/t steel-4 kg/t steel of carbon powder, 3kg/t steel-4 kg/t steel of silicon carbide, 5kg/t steel-6 kg/t steel of manganese-silicon alloy, 1.2kg/t steel-1.5 kg/t steel of aluminum ingot and 1.5kg/t steel of silicon-barium-calcium, wherein on the basis of the quantity requirements, the rest raw material components in each ton of steel are scrap steel, and the scrap steel is approximately 90-95 percent.

In this embodiment, by limiting the total amount of raw materials required, the raw materials can be prevented from being added randomly, thereby ensuring the smelting effect.

In the above examples, the percentage requirements of the amount of the added raw materials and the steel in the pre-reduction process are as follows: 0.1 to 0.15 percent of carbon powder, 0.1 to 0.15 percent of silicon carbide and 0.5 to 0.6 percent of silicon-manganese alloy; in the reduction process, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 0.2 to 0.25 percent of carbon powder, 0.15 to 0.25 percent of silicon carbide, 0.6 to 1 percent of high-carbon ferromanganese and 0.4 to 0.6 percent of ferrosilicon; in the tapping process, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 0.15 to 0.2 percent of silicon-barium-calcium and 0.12 to 0.15 percent of aluminum ingot.

It is understood that the percentage requirement of the quantity in each process can be understood as the following requirement: in the pre-reduction process, the quantity of the added raw materials is required to be as follows: 1kg/t steel-1.5 kg/t steel with carbon powder, 1kg/t steel-1.5 kg/t steel with silicon carbide and 5kg/t steel-6 kg/t steel with silicon-manganese alloy. In the reduction process, the quantity of the added raw materials is required to be as follows: 2-2.5 kg/t steel with carbon powder, 1.5-2.5 kg/t steel with silicon carbide, 6-10 kg/t steel with high-carbon ferromanganese, and 4-6 kg/t steel with ferrosilicon. In the tapping process, the quantity of the added raw materials is required to be as follows: 1.5kg/t steel-2 kg/t steel of silicon barium calcium and 1.2kg/t steel-1.5 kg/t steel of aluminum ingot.

It is noted that kg is in kilograms and t is in tons.

In the embodiment, in each step of the smelting process, the amount of the added raw materials is independently limited, so that the raw materials in each step can not be added randomly, and the treatment effect of each step is ensured. In addition, the quantity of the raw materials in each step is limited, so that the total quantity of the raw materials added in each step is ensured to meet the requirement, and the condition that the quantity of the raw materials in a single step is excessively added to cause the quantity of the raw materials in other steps to be reduced and the treatment effect of the other steps is influenced is avoided.

In the above examples, the percentage of the amount of raw material added to the steel at the time of charging the electric furnace is required to be: 2 to 3 percent of lime, 1.5 to 2 percent of iron ore and 0.7 to 1 percent of fluorite.

It will be understood that the quantity requirement of the raw materials added during charging of the electric furnace can also be understood as the following requirement: 20kg/t to 30kg/t steel of lime, 15kg/t to 20kg/t steel of iron ore and 7kg/t to 10kg/t steel of fluorite.

The steel scraps comprise large steel scraps, medium steel scraps and small steel scraps, wherein the steel scraps, the medium steel scraps and the small steel scraps are as follows, the weight ratio is 0.8-1.2: 2-4: 0.8 to 1.2 by weight. Specifically, for example, large scrap, medium scrap, and small scrap are charged at a ratio of 1:3:1, or at a ratio of 1.1:3.2:1, or at a ratio of 0.8:3: 0.8.

When dephosphorization and decarbonization are carried out by oxidation, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 2 to 3 percent of lime and 0.7 to 1 percent of fluorite.

It is understood that the quantity requirement of the added raw materials in the process of dephosphorization and decarbonization by oxidation can also be understood as the following requirement: 20kg/t to 30kg/t steel of lime and 7kg/t to 10kg/t steel of fluorite.

When the oxidation slag is completely pulled out after the oxidation is finished, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 2 to 3 percent of lime and 0.7 to 1 percent of fluorite.

It can be understood that the requirement of the amount of the raw material to be added when the oxidation slag is completely removed after the oxidation is completed can also be understood as the following requirement: 20kg/t to 30kg/t steel of lime and 7kg/t to 10kg/t steel of fluorite.

In the embodiment, in each step of the smelting process, the amount of the added raw materials is independently limited, so that the raw materials in each step can not be added randomly, and the treatment effect of each step is ensured. In addition, the quantity of the raw materials in each step is limited, so that the total quantity of the raw materials added in each step is ensured to meet the requirement, and the condition that the quantity of the raw materials in a single step is excessively added to cause the quantity of the raw materials in other steps to be reduced and the treatment effect of the other steps is influenced is avoided. The proportion of large scrap steel, medium scrap steel and small scrap steel is limited, full utilization of various scrap steels with different specifications is facilitated, and the utilization rate of the scrap steel is improved.

It should be noted that the bulk weight of the large scrap is greater than 50kg and not more than 200kg, the bulk weight of the medium scrap is greater than 10kg and not more than 50kg, and the bulk weight of the small scrap is not more than 10 kg.

In the above embodiment, the oxygen blowing specifically includes: in the initial stage of oxidation, the oxygen lance is inserted 50 mm-200 mm below the liquid level of the steel, shallow blowing is carried out for 2 min-4 min, and the oxygen blowing pressure is 0.5 MPa-0.8 MPa. After shallow blowing is finished, the oxygen lance is inclined by 20-30 degrees in the middle and later oxidation stages, the oxygen lance is inserted into the position 150-300 mm below the liquid level of steel, and the molten pool is kept to be uniformly boiled until the weight percentage content of phosphorus, carbon and manganese in the molten pool is less than or equal to 0.006%, 0.21% and 0.23% respectively.

In the embodiment, by limiting the oxygen blowing time, the oxygen blowing depth and the oxygen blowing pressure, the oxygen blowing effectiveness is improved, and the oxygen blowing ineffectiveness caused by too short oxygen blowing time and too shallow oxygen blowing depth is avoided. And the method is also favorable for accelerating the oxidation process and improving the smelting efficiency.

In any of the above embodiments, the molding process includes a cast feeding, a riser 106 setting, a chill setting, and a tilt casting, as shown in fig. 2 and 3.

In this embodiment, by performing the casting feeding in the molding process, the contraction phenomenon in the switch tie 10 is facilitated to be reduced. The riser 106 is arranged to facilitate the supplement of metal solution, thereby further reducing the occurrence of shrinkage cavity phenomenon. By arranging the chilling blocks, the switch tie 10 is chilled conveniently, and the defect of shrinkage cavity is reduced. The inclined casting mode is favorable for improving the fluidity of the metal liquid, and further the shrinkage cavity phenomenon can be reduced.

In the above embodiment, the ratio of the casting feeding is 1% to 3%. The risers 106 are arranged on the casting end surface 108 of the switch tie 10 and are positioned on the rib plates 104 of the switch tie 10. The chiller comprises a first chiller 100 arranged on the top plate of the switch tie and a second chiller 114 arranged on an ear plate 116, and the chiller is a bright chiller. The inclination angle of the inclined pouring is 6-8 degrees. In the molding process, the draft angle is 1: 20.

In the embodiment, the ratio of the casting feeding is limited within a certain range, so that shrinkage cavities can be reduced, and material waste caused by overlarge ratio can be avoided. The gating system 110 is disposed at the end of the switch tie where the risers 106 are located. The riser is arranged on the casting end face 108 of the switch tie 10, namely, the riser is arranged at a higher position during casting, so that supplemented metal solution can flow to a lower position, namely to the non-casting end face 102, and the effect of preventing shrinkage cavities is ensured. The inclination angle of the inclined pouring is limited to 6-8 degrees, so that the fluidity of the metal liquid can be improved, and the over-high flow speed of the metal solution can be avoided. The draft is set to 1: and 20, the smoothness of the die drawing is convenient to improve.

Furthermore, in the molding process, the zircon powder coating is uniformly sprayed on the surfaces of the upper casting mold and the lower casting mold for 2 times, so that the surface strength of the casting molds is ensured, and the sand inclusion defect is reduced.

As shown in FIG. 5, in the above embodiment, the heat treatment process is normalization, the holding temperature of the normalization is 800 ℃ to 1000 ℃, and the holding time of the normalization is 2 hours to 4 hours.

In the embodiment, the normalizing treatment is adopted, so that the toughness of the switch tie is favorably improved, and the service life of the switch tie is prolonged.

As shown in fig. 4, according to an embodiment of a second aspect of the present invention, there is provided a switch tie 10 including: the lifting device comprises a top plate 112 and vertical plates 118, wherein the vertical plates 118 are respectively arranged on two sides of the top plate 112, and an included angle is formed between each vertical plate 118 and the top plate 112; the ear plate 116 is arranged at one end of each vertical plate 118 far away from the top plate 112; the plurality of rib plates are arranged between the two vertical plates 118 and are arranged at intervals; the switch tie 10 is integrally cast and molded by the method for producing the switch tie of any one of the embodiments of the first aspect.

In this embodiment, the switch tie 10 is integrally cast and molded by using the switch tie production method of any one of the above embodiments, so that all the advantages of the above embodiments are achieved, and details are not described herein. The switch tie 10 produced by the embodiment reduces the defects of air holes, shrinkage cavities and the like, and has the advantages of higher strength and rigidity, good toughness and long service life. In addition, the switch tie 10 adopts the arrangement of the top plate 112, the vertical plate 118, the ear plate 116 and the rib plate, so that the structure is simple, all parts are integrally formed, the rigidity is good, and the switch tie 10 is not easy to deform during assembly.

The invention provides a production method of a switch tie according to a specific embodiment, aiming at replacing a concrete switch tie with a cast steel switch tie and providing a casting process which can improve the casting defects of air holes, sand inclusion, shrinkage cavities and the like of a casting and ensure that the quality of the casting meets the requirements of the switch tie.

In order to achieve the above purpose, the technical solution of the present embodiment is:

a method for producing cast steel switch tie for switch assembly selects molten steel of ZG30Mn brand smelted by an electric arc furnace and adopting a proper smelting process as raw materials of the cast steel switch tie, and eliminates the defects of air holes, slag inclusion, shrinkage cavity and the like in the casting process by reasonably designing a modeling process and a normalizing heat treatment process so as to ensure the quality of castings.

Specifically, the smelting process adopts an oxidation method for smelting, and an oxidation mode combining ore and oxygen is selected; the method is characterized in that the defect of air holes in the casting mould is eliminated by using a deoxidation mode of diffusion deoxidation of carbon powder and silicon carbide powder, deoxidation of manganese-silicon alloy precipitation and deoxidation combination in an aluminum block and a silicon-barium-calcium alloy package. The molding process adopts a 2% casting shrinkage ruler, a heat-preservation riser, a chill and an inclined pouring mode to remove the defects of shrinkage cavity and the like.

More specifically, 20 kg-30 kg/t steel of lime, 15 kg-20 kg/t steel of iron ore, 7 kg-10 kg/t steel of fluorite, 9 t-10 t steel of scrap steel, 0.5 MPa-0.8 MPa oxygen pressure, 3 kg-4 kg/t steel of carbon powder, 3 kg-4 kg/t steel of silicon carbide, 5 kg-6 kg/t steel of manganese-silicon alloy, 1.2 kg-1.5 kg/t steel of aluminum ingot and 1.5 kg-2 kg/t steel of silicon-barium-calcium are added into the bottom of the smelting process furnace. The molding process adopts the mode that the surfaces of an upper casting mold and a lower casting mold are uniformly sprayed with zircon powder coating for 2 times, so that the surface strength of the casting molds is ensured, and the defect of sand inclusion is eliminated.

It should be noted that, in the cast steel switch tie produced by the technical scheme provided in the embodiment, the ear plate, the rib plate, the vertical plate and the like of the switch tie are integrally formed, so that the overall rigidity of the cast steel switch tie is greatly improved, the deformation of the switch tie in the assembling and using process can be effectively prevented, and the spatial position of each part of the switch on the switch tie is prevented from being deviated. Meanwhile, the ZG30Mn steel grade has enough mechanical property indexes and good welding and cutting properties, and is convenient for implementation of the subsequent machining process of the cast steel switch tie.

The specific implementation mode is as follows:

a production method of a cast steel switch tie for switch assembly comprises the following processes: smelting process, molding process and heat treatment process.

(1) An electric furnace smelting process comprises the following steps: the electric furnace smelting comprises the working procedures of electric furnace charging, oxidation dephosphorization decarburization, pre-reduction, tapping and final deoxidation, and the specific working procedures comprise the following steps:

a. and (4) charging in an electric furnace. Before charging, 220kg of lime, 150kg of iron ore and 70kg of fluorite are added into the furnace for slagging at the bottom of the furnace. Meanwhile, the scrap steel in the charging bucket is reasonably matched according to the size (the weight of the block is 50 kg-200 kg), the size (the weight of the block is 10 kg-50 kg) and the size, and 9.2t of scrap steel is loaded.

b. And (4) carrying out oxidation dephosphorization and decarburization. 60kg of lime and 30kg of fluorite are rapidly added for dephosphorization at the initial stage of oxidation. After the slag is formed, oxygen blowing is started, an oxygen blowing pipe is inserted 50-200 mm below the liquid level of the steel, shallow blowing is carried out for 3 minutes, and the oxygen blowing pressure is 0.6 MPa. And in the middle and later oxidation stages, the oxygen lance is adjusted, is inclined by about 30 degrees and is inserted into the position 150-300 mm below the liquid level of the steel to keep the molten pool uniformly boiling. Oxidation end point, P (phosphorus): 0.006%, C (carbon): 0.21%, Mn (manganese): 0.23 percent. After the oxidation is finished, the oxidation slag is completely removed, 80kg of lime and 30kg of fluorite are added, and slag is formed.

c. And (4) pre-reducing. After the slag is formed, 10kg of carbon powder, 10kg of silicon carbide and 50kg of silicon-manganese alloy are quickly added for pre-reduction.

d. And (4) reducing. 22kg of carbon powder, 18kg of silicon carbide, 78kg of high-carbon ferromanganese and 46kg of ferrosilicon are added in the reduction process, the slag reducibility is kept, and the chemical components of the molten steel are adjusted.

e. And (6) tapping. Tapping temperature is 1610 ℃, and 15kg of silicon-barium-calcium and 12kg of aluminum ingot are added into a ladle for final deoxidation treatment.

(2) The molding process comprises the following steps: as shown in fig. 1 to fig. 3, heat-insulating risers with a diameter of 100mm to 200mm, for example 150mm, are arranged at part of the rib plates. There are 8 risers in total from the pouring end. The first chilling block is arranged at the top plate, and the second chilling block is arranged at the lug plate. The first chills are 35mm thick and spaced apart with a gap of 8mm to 12mm, for example 10 mm. The molding process adopts 2% casting shrinkage, the inclined pouring angle is 6-8 degrees, and the draft angle is 1: 20.

(3) and (3) a heat treatment process, wherein the heat treatment process adopts a normalizing process, and the heat is preserved for 3 hours at 880 ℃, and is specifically shown in figure 5.

(4) Through examination, in the example of the embodiment, the statistical results of the chemical components and the mechanical properties of the test piece are as follows:

in the above table, wt% means weight percent.

In the specific embodiment, the chemical components of the test piece completely meet the chemical component range of ZG30Mn steel grade, and the mechanical properties of the test piece are higher than those of ZG30Mn steel grade.

The specific embodiment has the following beneficial effects:

firstly, compared with a concrete switch tie, the cast steel switch tie has certain improvement on material performance.

Secondly, the switch tie prepared by the production method in the embodiment effectively reduces the defects of air holes, shrinkage porosity, slag inclusion and the like which may occur in the casting process, and ensures the quality of the switch tie.

Furthermore, all parts of the switch tie are integrally formed, so that the overall rigidity of the cast steel switch tie is greatly improved, the deformation of the switch tie in the assembling and using process can be effectively prevented, and the spatial positions of all parts of the switch on the switch tie are prevented from being deviated.

In addition, the embodiment adopts ZG30Mn steel grade, which not only has enough mechanical property index, but also has good welding and cutting properties, and is convenient for the implementation of the subsequent machining process of the cast steel switch tie.

The embodiment provided by the invention is described in detail with reference to the attached drawings, and through the embodiment, the defects of air holes, shrinkage cavities and the like in the switch tie are effectively reduced, the rigidity and the strength of the switch tie are improved, the service life of the switch tie is prolonged, and the switch tie is simple in structure and easy to produce.

In embodiments according to the present invention, the terms "first", "second", "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the term "plurality" means two or more unless expressly limited otherwise. The terms "mounted," "connected," "fixed," and the like are to be construed broadly, and for example, "connected" may be a fixed connection, a removable connection, or an integral connection; "coupled" may be direct or indirect through an intermediary. Specific meanings of the above terms in the embodiments according to the present invention can be understood by those of ordinary skill in the art according to specific situations.

In the description of the embodiments according to the present invention, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", and the like indicate orientations or positional relationships based on those shown in the drawings, only for convenience of description and simplification of description of the embodiments according to the present invention, and do not indicate or imply that the referred devices or units must have a specific direction, be configured and operated in a specific orientation, and thus, should not be construed as limiting the embodiments according to the present invention.

In the description herein, the description of the terms "one embodiment," "some embodiments," "specific embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example in accordance with the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above is only a preferred embodiment according to the present invention, and is not intended to limit the embodiment according to the present invention, and various modifications and variations may be made to the embodiment according to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiment according to the present invention should be included in the protection scope of the embodiment according to the present invention.

Claims

1. A production method of a switch tie comprises a smelting process, a molding process and a heat treatment process, and is characterized in that,

the smelting process comprises an oxidation method and a smelting process,

2. The method for producing a switch tie according to claim 1,

the smelting process comprises the following steps:

charging in an electric furnace: adding lime, iron ore and fluorite into the electric furnace, and simultaneously adding waste steel into the charging bucket;

oxidation dephosphorization and decarbonization: adding limestone and fluorite into an electric furnace, blowing oxygen after furnace slag is formed, drawing out oxidation slag after oxidation is finished, adding lime and fluorite, and slagging;

pre-reduction: after the slag is formed, adding carbon powder, silicon carbide and silicon-manganese alloy into the electric furnace, and performing diffusion deoxidation;

reduction: adding carbon powder, silicon carbide, high-carbon ferromanganese and ferrosilicon alloy into an electric furnace, and performing precipitation deoxidation;

tapping: tapping at 1500-1800 ℃, adding silicon barium calcium and aluminum ingots into a ladle, and performing final deoxidation.

3. The method for producing a switch tie according to claim 2,

in the smelting process, the total amount of the added raw materials and the percentage requirement of the steel are as follows: 2 to 3 percent of lime, 1.5 to 2 percent of iron ore, 0.7 to 1 percent of fluorite, 90 to 95 percent of scrap steel, 0.3 to 0.4 percent of carbon powder, 0.3 to 0.4 percent of silicon carbide, 0.5 to 0.6 percent of manganese-silicon alloy, 0.12 to 0.15 percent of aluminum ingot and 0.15 to 0.2 percent of calcium silicon-barium;

additionally, the oxygen pressure is 0.5MPa to 0.8 MPa.

4. The method for producing a switch tie according to claim 3,

in the pre-reduction process, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 0.1 to 0.15 percent of carbon powder, 0.1 to 0.15 percent of silicon carbide and 0.5 to 0.6 percent of silicon-manganese alloy;

in the reduction process, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 0.2 to 0.25 percent of carbon powder, 0.15 to 0.25 percent of silicon carbide, 0.6 to 1 percent of high-carbon ferromanganese and 0.4 to 0.6 percent of ferrosilicon;

in the tapping process, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 0.15 to 0.2 percent of silicon-barium-calcium and 0.12 to 0.15 percent of aluminum ingot.

5. The method for producing a switch tie according to claim 3,

when the electric furnace is charged, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 2 to 3 percent of lime, 1.5 to 2 percent of iron ore and 0.7 to 1 percent of fluorite;

the steel scraps comprise large steel scraps, medium steel scraps and small steel scraps, wherein the mass ratio of the large steel scraps, the medium steel scraps and the small steel scraps is 0.8-1.2: 2-4: loading in a weight ratio of 0.8-1.2;

during the oxidation dephosphorization and decarburization, the percentage requirements of the quantity of the added raw materials and the steel are as follows: 2 to 3 percent of lime and 0.7 to 1 percent of fluorite;

6. The method for producing a switch tie according to claim 3,

the oxygen blowing specifically comprises:

the oxygen lance is inserted 50 mm-200 mm below the liquid level of the steel, shallow blowing is carried out for 2 min-4 min, and the oxygen blowing pressure is 0.5 MPa-0.8 MPa;

after the shallow blowing is finished, the oxygen lance is inclined by 20-30 degrees, and is inserted into the position 150-300 mm below the liquid level of steel, and the molten pool is kept to be uniformly boiled until the weight percentage content of phosphorus, carbon and manganese in the molten pool is less than or equal to 0.006%, 0.21% and 0.23% respectively.

7. The switch tie production method according to any one of claims 1 to 6,

the molding process comprises casting feeding, riser setting, chill setting and inclined pouring.

8. The method for producing a switch tie according to claim 7,

the casting feeding proportion is 1% -3%;

the riser is arranged at the pouring end of the switch tie and is positioned at a rib plate of the switch tie;

the chilling blocks are arranged on the top of the switch tie and the ear plates, and the chilling blocks are bright chilling blocks;

the inclination angle of the inclined pouring is 6-8 degrees;

in the molding process, the draft angle of the mold is 1: 20.

9. The method for producing a switch tie according to claim 8,

the heat treatment process is normalizing, the heat preservation temperature of the normalizing is 800-1000 ℃, and the heat preservation time of the normalizing is 2-4 hours.

10. A switch tie, comprising:

the lifting device comprises a top plate and vertical plates, wherein the vertical plates are arranged on two sides of the top plate respectively, and an included angle is formed between each vertical plate and the top plate;

the end, far away from the top plate, of each vertical plate is provided with the ear plate;

the rib plates are arranged between the two vertical plates and are arranged at intervals;

the switch tie is integrally cast and molded by the method for producing a switch tie according to any one of claims 1 to 9.