阅读说明：本技术 一种输送管的制备方法及输送管 (Preparation method of conveying pipe and conveying pipe ) 是由 王峰 陈波 崔海霞 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种输送管的制备方法及输送管,该方法包括如下步骤：在离心铸造机管端处均布固定4-8片预制的陶瓷骨架；熔炼金属液并将熔炼好的金属液倒入离心铸造机浇注成型壁厚为2-3mm的管坯；其中,金属液各元素含量质量百分比为：碳2.2%～3.2%,硅0.8%～1.5%,锰0.5%～0.8%,铬10%～15%,钒0.5%～2.0%,磷+硫≤0.1%,余量为铁及其他元素；将制备好的管坯放入热处理炉,缓慢升温至920～980℃,保温3～6h后取出,将取出的管坯冷却后再次放入热处理炉缓慢升温至250～350℃,保温3～6h后获成品输送管。本申请提高输送管整体耐磨性能,同时增强铸管断裂抵抗性。(The invention discloses a preparation method of a conveying pipe and the conveying pipe, wherein the method comprises the following steps: 4-8 prefabricated ceramic frameworks are uniformly distributed and fixed at the pipe end of the centrifugal casting machine; smelting molten metal and pouring the smelted molten metal into a centrifugal casting machine to cast and mold a tube blank with the wall thickness of 2-3 mm; wherein the molten metal comprises the following elements in percentage by mass: 2.2-3.2% of carbon, 0.8-1.5% of silicon, 0.5-0.8% of manganese, 10-15% of chromium, 0.5-2.0% of vanadium, less than or equal to 0.1% of phosphorus and sulfur, and the balance of iron and other elements; and (3) putting the prepared tube blank into a heat treatment furnace, slowly heating to 920-980 ℃, preserving heat for 3-6 h, taking out, cooling the taken tube blank, putting the tube blank into the heat treatment furnace again, slowly heating to 250-350 ℃, preserving heat for 3-6 h, and obtaining a finished product conveying pipe. The application improves the whole wear resistance of the conveying pipe and simultaneously enhances the fracture resistance of the cast pipe.)

1. The preparation method of the conveying pipe is characterized by comprising the following steps:

4-8 prefabricated ceramic frameworks are uniformly distributed and fixed at the pipe end of the centrifugal casting machine;

smelting molten metal and pouring the smelted molten metal into a centrifugal casting machine to cast and mold a tube blank with the wall thickness of 2-3 mm; wherein the molten metal comprises the following elements in percentage by mass: 2.2-3.2% of carbon, 0.8-1.5% of silicon, 0.5-0.8% of manganese, 10-15% of chromium, 0.5-2.0% of vanadium, less than or equal to 0.1% of phosphorus and sulfur, and the balance of iron and other elements;

and (3) putting the prepared tube blank into a heat treatment furnace, slowly heating to 920-980 ℃, preserving heat for 3-6 h, taking out, cooling the taken tube blank, putting the tube blank into the heat treatment furnace again, slowly heating to 250-350 ℃, preserving heat for 3-6 h, and obtaining a finished product conveying pipe.

2. The method for preparing the conveying pipe according to claim 1, wherein in the step of smelting molten metal, carbon-chromium iron FeCr65C1.0 is selected as a chromium additive, and ferrovanadium is selected as a vanadium additive.

3. The method for manufacturing the conveying pipe according to claim 1, wherein the molten metal melting temperature is 1500-1600 ℃ and the pouring temperature is 1450-1550 ℃.

4. The method of manufacturing a duct according to claim 1, wherein the smelting of the metal bath is carried out in a medium frequency induction smelting furnace.

5. A method for producing a transport pipe according to claim 1, characterized in that the tube blank is cooled in the form of: and (4) rotating the spray header in the tube blank to spray and cool the tube blank.

6. The method of making a delivery tube of claim 1, wherein the ceramic backbone comprises mounting legs.

7. The method of manufacturing a delivery tube of claim 1, wherein the ceramic backbone is prepared as follows:

mixing and stirring nickel oxide, aluminum and zirconia with the granularity of 150-400 meshes according to a certain proportion, dripping a polyvinyl alcohol solution into the mixture, standing the mixture for ageing for 10-20 hours, and then putting the mixture into an oven at 100-200 ℃ for drying;

putting the dried blank into a grinding machine, adding yttrium oxide with the granularity of 100-200 meshes, grinding for 5-10 h, fully mixing uniformly, and putting into a grinding tool for compression molding;

and (3) putting the formed blank into a sintering furnace, and sintering at 1500-1600 ℃ for 10-20 h to prepare the ceramic framework.

8. The method of manufacturing a delivery tube according to claim 7, wherein the polyvinyl alcohol solution has a concentration of 3%.

9. The manufacturing method of the conveying pipe according to claim 7, wherein the thickness of the blank pressed by the grinding tool is 1-2 mm.

10. A delivery tube prepared according to the method of any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of conveying pipes, in particular to a conveying pipe and a manufacturing method thereof.

Background

The conveying pipe is an essential part in the concrete pumping process. In the pumping process, carry the jar with the concrete through the conveyer pipe pump to tens meters high operation district, the building stones in the concrete are to conveyer pipe wall scouring and wearing under high-pressure operation environment, because the direction of motion of concrete material changes in union coupling department, along with violent impact, aggravate the wearing and tearing of geminate transistors end department. This requires the pipe to have lightweight, high wear resistance and impact resistance.

At present, the conveying pipe is divided into a single-layer pipe and a double-layer pipe. 45Mn2 is mostly adopted as a raw material of the single-layer pipe conveying pipe, and the inner wall of the conveying pipe is hardened through high-frequency quenching treatment to enhance the wear resistance of the conveying pipe. The double-layer pipe conveying pipe mostly adopts a high-chromium steel pipe as an inner pipe, the thickness of the inner pipe is 2-3mm, the pipe wall is completely quenched through an integral quenching process, the integral steel pipe is guaranteed to have higher hardness, and the outer pipe adopts low-alloy structural steel, so that the integral toughness of the conveying pipe is enhanced. The current production of mono-and double-layer pipes has the following disadvantages:

(1) the quenching process is poor: due to the fact that the pipe wall of the conveying pipe is thin, the quenching process is difficult, the hardenability of the steel pipe raw material is poor, the problems that radial hardness distribution is uneven, the depth difference of a hardening layer is obvious and the like exist in the conveying pipe, the pipe wall is abraded unevenly in the process that the conveying pipe is subjected to material washing and impact, weak points exist, and finally the risk of pipe explosion is caused. (2) The weak point is obvious: in the material conveying process of the conveying pipe, the pipes are distributed in an M shape, stone hard objects in the material are seriously impacted and worn at the end of the pipe, and the preparation process at the end of the pipe is not strengthened in the preparation process of the conveying pipe. With the erosion of the material to the weak point, the weak point of the conveying pipe is cracked under the high-pressure working environment, so that the conveying pipe is failed, and the conveying pipe needs to be integrally replaced. (3) Cost: the inner pipe of the double-layer conveying pipe is made of a high-chromium steel pipe, and the double-layer conveying pipe is complex in preparation process, high in manufacturing difficulty and high in cost.

Disclosure of Invention

The invention aims to provide a conveying pipe and a preparation method thereof, and aims to solve the problem that the conveying pipe in the prior art is poor in wear resistance and impact resistance.

In order to achieve the purpose, the invention is realized by adopting the following technical scheme:

a preparation method of a conveying pipe comprises the following steps:

4-8 prefabricated ceramic frameworks are uniformly distributed and fixed at the pipe end of the centrifugal casting machine;

smelting molten metal and pouring the smelted molten metal into a centrifugal casting machine to cast and mold a tube blank with the wall thickness of 2-3 mm; wherein the molten metal comprises the following elements in percentage by mass: 2.2-3.2% of carbon, 0.8-1.5% of silicon, 0.5-0.8% of manganese, 10-15% of chromium, 0.5-2.0% of vanadium, less than or equal to 0.1% of phosphorus and sulfur, and the balance of iron and other elements;

and (3) putting the prepared tube blank into a heat treatment furnace, slowly heating to 920-980 ℃, preserving heat for 3-6 h, taking out, cooling the taken tube blank, putting the tube blank into the heat treatment furnace again, slowly heating to 250-350 ℃, preserving heat for 3-6 h, and obtaining a finished product conveying pipe.

Further, in the step of smelting the molten metal, carbon ferrochrome FeCr65C1.0 is selected as a chromium additive, and ferrovanadium is selected as a vanadium additive.

Further, the molten metal smelting temperature is 1500-1600 ℃, and the pouring temperature is 1450-1550 ℃.

Further, the smelting of the molten metal is carried out in a medium-frequency induction smelting furnace.

Further, the cooling form of the tube blank is as follows: and (4) rotating the spray header in the tube blank to spray and cool the tube blank.

Further, the ceramic skeleton includes a mounting leg.

Further, the preparation method of the ceramic skeleton comprises the following steps:

mixing and stirring nickel oxide, aluminum and zirconia with the granularity of 150-400 meshes according to a certain proportion, dripping a polyvinyl alcohol solution into the mixture, standing the mixture for ageing for 10-20 hours, and then putting the mixture into an oven at 100-200 ℃ for drying;

putting the dried blank into a grinding machine, adding yttrium oxide with the granularity of 100-200 meshes, grinding for 5-10 h, fully mixing uniformly, and putting into a grinding tool for compression molding;

and (3) putting the formed blank into a sintering furnace, and sintering at 1500-1600 ℃ for 10-20 h to prepare the ceramic framework.

Further, the concentration of the polyvinyl alcohol solution is 3%.

Further, the thickness of the blank pressed and formed by the grinding tool is 1-2 mm.

The invention also discloses a conveying pipe prepared by the preparation method.

According to the technical scheme, the embodiment of the invention at least has the following effects:

1. according to the preparation method, the conveying pipe with high-chromium cast iron as the base body can be manufactured by limiting the mass percentage of each element in the molten metal, the integral wear resistance of the conveying pipe is improved, the mass percentage of vanadium and chromium are limited in the molten metal, the vanadium can refine the grain structure in the cast iron, the vanadium-containing carbide VC has high hardness, the wear resistance of the conveying pipe is ensured, and meanwhile, the VC can enhance the fracture resistance of the cast pipe;

2. according to the concrete conveying device, zirconia is distributed at the position of the pipe end to serve as a main ceramic framework, and the ceramic framework can well resist impact and abrasion to the pipe end when concrete is conveyed and changes direction;

3. the method adopts an integral heat treatment process, the vanadium-containing high-chromium alloy cast pipe is hardened, the combination of the alloy cast pipe and a ceramic framework is strengthened, the internal stress of a conveying pipe is reduced, and the integral toughness is improved;

4. the Rockwell hardness of the inner wall of the cast pipe of the conveying pipe prepared by the preparation method is not lower than 55HRC, the impact energy is not lower than 7.5J, and the wear resistance is improved by more than 60%;

5. this application imbeds the conveyer pipe both ends with ceramic skeleton, adopts pre-buried form and cast the pipe and fuse integrative under high temperature, and the cohesion is strong, has high wear-resisting and high obdurability, reduces the impact wear of high-speed material to pipe end department, alleviates the economic loss that whole root pipe change brought.

Drawings

FIG. 1 is a schematic view of a ceramic backbone of the present invention;

FIG. 2 is a schematic view of the arrangement of the ceramic skeleton of the present invention;

FIG. 3 is a perspective view of a delivery tube having a ceramic backbone according to the present invention.

Detailed Description

In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further described with the specific embodiments.

In this application, VC- - -Vanadiumcarbide vanadium carbide.

A preparation method of a conveying pipe comprises the following steps: 4-8 prefabricated ceramic frameworks are uniformly distributed and fixed at the pipe end of the centrifugal casting machine; smelting molten metal and pouring the smelted molten metal into a centrifugal casting machine to cast and mold a tube blank with the wall thickness of 2-3 mm; wherein the molten metal comprises the following elements in percentage by mass: 2.2-3.2% of carbon, 0.8-1.5% of silicon, 0.5-0.8% of manganese, 10-15% of chromium, 0.5-2.0% of vanadium, less than or equal to 0.1% of phosphorus and sulfur, and the balance of iron and other elements; and (3) putting the prepared tube blank into a heat treatment furnace, slowly heating to 920-980 ℃, preserving heat for 3-6 h, taking out, cooling the taken tube blank, putting the tube blank into the heat treatment furnace again, slowly heating to 250-350 ℃, preserving heat for 3-6 h, and obtaining a finished product conveying pipe.

According to the preparation method, the delivery pipe with high-chromium cast iron as the base body can be manufactured by limiting the mass percentage of each element in the molten metal, the integral wear resistance of the delivery pipe is improved, the mass percentage of vanadium and chromium are limited in the molten metal, the vanadium can refine the grain structure in the cast iron, the vanadium-containing carbide VC has high hardness, the wear resistance of the delivery pipe is ensured, and meanwhile, the VC can enhance the fracture resistance of the cast pipe.

The present application is illustrated by the following specific examples.

Example 1

Step (1) preparation of wear-resistant ceramics: 150 parts of zirconia powder with 150 meshes, 50 parts of nickel oxide powder with 200 meshes, 200 parts of alumina powder with 150 meshes and 20 parts of aluminum powder with 150 meshes are selected. And after fully and uniformly mixing the powder, dropwise adding 35 parts of 3% polyvinyl alcohol solution, simultaneously stirring uniformly, standing for 20 hours for ageing, putting the premixed powder into a 100 ℃ oven for drying for 2 hours, adding 5 parts of 100-mesh yttrium oxide powder, putting the mixture into a grinding machine for grinding for 10 hours, fully and uniformly mixing, putting the mixture into a grinding tool for compression molding, wherein the blank thickness is 1.8 mm. And sintering the formed blank at 1600 ℃ for 15h to prepare the pre-buried ceramic framework of the conveying pipe.

Step (2) ceramic pre-embedding installation: and (2) mounting the ceramic blank prepared in the step (1) into a centrifugal casting machine type cavity, and uniformly distributing and mounting 6 ceramic frameworks along the periphery of the pipe end.

Step (3), centrifugal casting: selecting a medium-frequency smelting furnace to smelt molten metal, wherein the molten metal comprises the following elements in percentage by weight: 2.2 percent of carbon, 0.8 percent of silicon, 0.8 percent of manganese, 12 percent of chromium, 0.5 percent of vanadium, less than or equal to 0.1 percent of phosphorus and sulfur, and the balance of iron and other elements. Medium carbon ferrochrome FeCr65C1.0 is selected as a chromium additive, and ferrovanadium is selected as a vanadium additive. The medium frequency melting temperature is 1500 ℃, centrifugal casting is started at the casting temperature of 1450 ℃, and the inner wall of the conveying pipe is 2.5 mm.

Step (4) integral heat treatment: and (4) putting the conveying pipe prepared in the step (3) into a heat treatment furnace, slowly heating to 980 ℃, preserving heat for 4 hours, and then discharging from the furnace pipe for spray cooling. And then putting the conveying pipe into a heat treatment furnace, slowly heating to 300 ℃, preserving heat for 3 hours, cooling to room temperature in the furnace, and taking out.

The average hardness of the cast tube matrix of the conveying pipe inner tube prepared by the invention is 59HRC, the average impact absorption work is 9.5J, the average hardness of the ceramic framework is 85HRA, through a wet sand rubber wheel abrasion test, the abrasion rate is 0.054%, and the abrasion resistance is improved by 67%.

Example 2

Step (1) preparation of wear-resistant ceramics: 250 parts of zirconia powder with the granularity of 400 meshes, 50 parts of nickel oxide powder with the granularity of 200 meshes, 100 parts of alumina powder with the granularity of 200 meshes and 20 parts of aluminum powder with the granularity of 200 meshes are selected. And after fully and uniformly mixing the powder, dropwise adding 35 parts of 3% polyvinyl alcohol solution, simultaneously stirring uniformly, standing for ageing for 15 hours, putting the premixed powder into an oven at 150 ℃ for drying for 2 hours, adding 5 parts of 100-mesh yttrium oxide powder, putting the mixture into a grinding machine for grinding for 10 hours, fully and uniformly mixing, putting the mixture into a grinding tool for compression molding, wherein the blank thickness is 1.0 mm. And sintering the formed blank at 1500 ℃ for 15h to prepare the pre-embedded ceramic framework of the conveying pipe.

Step (2) ceramic pre-embedding installation: and (2) mounting the ceramic blank prepared in the step (1) into a centrifugal casting machine type cavity, and uniformly distributing and mounting 4 ceramic frameworks along the periphery of a pipe end.

Step (3), centrifugal casting: selecting a medium-frequency smelting furnace to smelt molten metal, wherein the molten metal comprises the following elements in percentage by weight: 2.6 percent of carbon, 1.5 percent of silicon, 0.5 percent of manganese, 10 percent of chromium, 1.0 percent of vanadium, less than or equal to 0.1 percent of phosphorus and sulfur, and the balance of iron and other elements. Medium carbon ferrochrome FeCr65C1.0 is selected as a chromium additive, and ferrovanadium is selected as a vanadium additive. The intermediate frequency smelting temperature is 1600 ℃, centrifugal casting is started at the casting temperature of 1550 ℃, and the inner wall of the conveying pipe is 2.0 mm.

Step (4) integral heat treatment: and (4) placing the conveying pipe prepared in the step (3) into a heat treatment furnace, slowly heating to 960 ℃, preserving heat for 4 hours, and discharging from the furnace pipe for spray cooling. And then putting the conveying pipe into a heat treatment furnace, slowly heating to 350 ℃, preserving heat for 6 hours, cooling the inside of the furnace to room temperature, and taking out.

According to the conveying pipe inner pipe prepared by the method, the average hardness of a casting pipe matrix is 57HRC, the average impact absorption work is 10.0J, the average hardness of a ceramic framework is 82HRA, through a wet sand rubber wheel abrasion test, the abrasion rate is 0.060%, and the abrasion resistance is improved by 63%.

Example 3

Step (1) preparation of wear-resistant ceramics: 150 parts of zirconia powder with the granularity of 200 meshes, 50 parts of nickel oxide powder with the granularity of 200 meshes, 200 parts of alumina powder with the granularity of 150 meshes and 20 parts of aluminum powder with the granularity of 150 meshes are selected. And after fully and uniformly mixing the powder, dropwise adding 35 parts of 3% polyvinyl alcohol solution, simultaneously stirring uniformly, standing for 20 hours for ageing, putting the premixed powder into a 200 ℃ oven for drying for 2 hours, adding 5 parts of 200-mesh yttrium oxide powder, putting the mixture into a grinding machine for grinding for 10 hours, fully and uniformly mixing, putting the mixture into a grinding tool for compression molding, wherein the blank thickness is 2.0 mm. And sintering the formed blank at 1600 ℃ for 20 hours to prepare the pre-buried ceramic framework of the conveying pipe.

Step (2) ceramic pre-embedding installation: and (2) mounting the ceramic blank prepared in the step (1) into a centrifugal casting machine type cavity, and uniformly distributing and mounting 8 ceramic frameworks along the periphery of a pipe end.

Step (3), centrifugal casting: selecting a medium-frequency smelting furnace to smelt molten metal, wherein the molten metal comprises the following elements in percentage by weight: 3.2 percent of carbon, 1.5 percent of silicon, 0.8 percent of manganese, 15 percent of chromium, 2.0 percent of vanadium, less than or equal to 0.1 percent of phosphorus and sulfur, and the balance of iron and other elements. Medium carbon ferrochrome FeCr65C1.0 is selected as a chromium additive, and ferrovanadium is selected as a vanadium additive. The intermediate frequency smelting temperature is 1550 ℃, centrifugal casting is started at the casting temperature of 1480 ℃, and the inner wall of the conveying pipe is 3.0 mm.

Step (4) integral heat treatment: and (4) placing the conveying pipe prepared in the step (3) into a heat treatment furnace, slowly heating to 920 ℃, keeping the temperature for 6 hours, and then discharging the product out of the furnace for spray cooling. And then putting the conveying pipe into a heat treatment furnace, slowly heating to 250 ℃, preserving heat for 5 hours, cooling to room temperature in the furnace, and taking out.

According to the conveying pipe inner pipe prepared by the method, the average hardness of a cast pipe matrix is 62HRC, the average impact absorption work is 7.5J, the average hardness of a ceramic framework is 87HRA, through a wet sand rubber wheel abrasion test, the abrasion rate is 0.037%, and the abrasion resistance is improved by 77%.

In the three embodiments, the ceramic framework 22 is prepared as shown in fig. 1 and fig. 2, and comprises the integral framework structure 12 and the mounting legs 11 positioned on the framework structure, so that the ceramic framework can be conveniently embedded into the cast pipe and fused with the cast pipe in a high-temperature casting environment, and the ceramic framework has strong bonding force and is not easy to fall off. Fig. 2 is a schematic view of the arrangement of the ceramic former 22 at the pipe end 21.

In other embodiments, the shape of the ceramic skeleton may be in other forms. Can design the ceramic skeleton subsection according to the operating mode requirement, the pre-buried requirement that can reach reinforcing pipe end wearability and toughness of skeleton of other structural style equally.

Example 4

Step (1) preparation of wear-resistant ceramics: 150 parts of zirconia powder with the granularity of 400 meshes, 50 parts of nickel oxide powder with the granularity of 150 meshes, 200 parts of alumina powder with the granularity of 400 meshes and 20 parts of aluminum powder with the granularity of 150 meshes are selected. And after fully and uniformly mixing the powder, dropwise adding 35 parts of 3% polyvinyl alcohol solution, simultaneously stirring uniformly, standing for 20 hours for ageing, putting the premixed powder into a 200 ℃ oven for drying for 2 hours, adding 5 parts of 200-mesh yttrium oxide powder, putting the mixture into a grinding machine for grinding for 5 hours, fully and uniformly mixing, putting the mixture into a grinding tool for compression molding, wherein the blank thickness is 2.0 mm. And sintering the formed blank at 1600 ℃ for 10 hours to prepare the pre-buried ceramic framework of the conveying pipe.

Step (2) ceramic pre-embedding installation: and (2) mounting the ceramic blank prepared in the step (1) into a centrifugal casting machine type cavity, and uniformly distributing and mounting 6 ceramic frameworks along the periphery of the pipe end.

Step (3), centrifugal casting: selecting a medium-frequency smelting furnace to smelt molten metal, wherein the molten metal comprises the following elements in percentage by weight: 3.2 percent of carbon, 0.8 percent of silicon, 0.6 percent of manganese, 15 percent of chromium, 1.5 percent of vanadium, less than or equal to 0.1 percent of phosphorus and sulfur, and the balance of iron and other elements. Medium carbon ferrochrome FeCr65C1.0 is selected as a chromium additive, and ferrovanadium is selected as a vanadium additive. The intermediate frequency smelting temperature is 1550 ℃, the centrifugal casting is started at the casting temperature of 1500 ℃, and the inner wall of the conveying pipe is 3.0 mm.

Step (4) integral heat treatment: and (4) putting the conveying pipe prepared in the step (3) into a heat treatment furnace, slowly heating to 980 ℃, preserving heat for 3 hours, and then discharging from the furnace pipe for spray cooling. And then putting the conveying pipe into a heat treatment furnace, slowly heating to 350 ℃, preserving heat for 6 hours, cooling the inside of the furnace to room temperature, and taking out.

According to the conveying pipe inner pipe prepared by the method, the average hardness of a casting pipe matrix is 61HRC, the average impact absorption work is 7.5J, the average hardness of a ceramic framework is 88HRA, through a wet sand rubber wheel abrasion test, the abrasion rate is 0.041%, and the abrasion resistance is improved by 74%.

Example 5

This embodiment provides a delivery tube made according to any of the four embodiments described above, as shown in figure 3.

According to the centrifugal casting conveying pipe, the embedded ceramic framework at the pipe end is combined with the cast pipe through high temperature, the framework form is not limited to the above, the ceramic framework subsection can be designed according to the working condition requirement, and the embedded frameworks of other structural forms can also meet the requirements of enhancing the wear resistance and toughness of the pipe end. The rare earth element is added into the ceramic skeleton, so that the risk of casting cracks can be reduced, and the addition of yttrium oxide is not limited.

The delivery pipe provided by the embodiment has the following advantages:

(1) the conveying pipe adopts a mature centrifugal casting process, and has the characteristics of uniform radial and axial material quality, no air holes, few impurities and the like. (2) The conveying pipe has high linearity, good forming effect and uniform wall thickness. (3) The high-chromium alloy of the cast pipe of the conveying pipe ensures high wear resistance of the whole, and the addition of vanadium can refine grain structure and improve the strength and toughness of the cast pipe. (4) The ceramic framework is embedded into the two ends of the conveying pipe, and is fused with the cast pipe at high temperature into a whole in an embedded mode, so that the bonding force is strong, the high wear resistance and the high strength and toughness are achieved, the impact wear of high-speed materials to the pipe end is reduced, and the economic loss caused by replacement of the whole pipe is reduced.

It will be appreciated by those skilled in the art that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed above are therefore to be considered in all respects as illustrative and not restrictive. All changes which come within the scope of or equivalence to the invention are intended to be embraced therein.