CN116037899A - A kind of manufacturing method of coal grinding liner - Google Patents

Abstract

The application relates to a method for manufacturing a coal grinding lining plate, which comprises the following steps: smelting the wear-resistant material and the carbon steel material simultaneously to obtain a molten wear-resistant material and a molten carbon steel material; step two: pouring molten wear-resistant material at a first temperature into the sand mold from the bottom of the sand mold through a bottom return pouring system, so that the bottom of the sand mold is filled with the molten wear-resistant material; step three: pouring a molten carbon steel material at a second temperature into the sand mold from the top of the sand mold through a rain pouring system, so that the molten carbon steel material and the molten wear-resistant material are mutually fused and combined, pouring the molten carbon steel material into a riser, feeding the casting in the sand mold by the molten carbon steel material in the riser, and cooling to obtain a lining plate blank with a metallurgical combination of the wear-resistant layer and the carbon steel layer; step four: cutting and removing a riser and a runner on a lining plate blank, and carrying out integral heat treatment after finishing treatment on the blank to obtain a coal grinding lining plate; step five: cutting the coal grinding lining plate into blocks, and machining the carbon steel layer of each coal grinding lining plate to meet the matching requirement of the coal mill. The method can obviously improve the production efficiency of the coal grinding lining plate, improve the quality of the coal grinding lining plate and prolong the service life of the coal grinding lining plate.

Description

A kind of manufacturing method of coal grinding liner

technical field

The present application relates to the technical field of industrial coal-fired boilers, in particular to a method for manufacturing a coal grinding liner.

Background technique

The coal grinding liner is the core part of the coal mill. The lump coal is rolled, rolled and ground by the coal grinding roller and the liner of the coal mill, and after being turned into powder, it is transported to the boiler by high-pressure airflow. Full combustion can significantly increase the combustion rate of coal. The structure of the coal grinding liner includes a carbon steel layer at the bottom and a wear-resistant layer at the top. The carbon steel layer has excellent machinability and is easy to match with the bottom plate after machining. The wear-resistant layer has high hardness and is used for grinding and pulverizing coal or ore, etc.

In the related technology, the coal grinding liner is usually manufactured by surfacing welding process, that is, a layer of wear-resistant material is surfacing on the processed circular steel plate to form a wear-resistant layer working surface. This manufacturing method has low work efficiency and surfacing welding The quality of layers is difficult to control.

Contents of the invention

In order to solve the deficiencies in the above research, this application proposes a manufacturing method of the coal grinding liner, which can significantly improve the production efficiency of the coal grinding liner, improve the quality of the coal grinding liner, and prolong the service life of the coal grinding liner .

The embodiment of the present application provides a method for manufacturing a coal grinding liner, including the following steps:

Step 1: Simultaneously smelting the wear-resistant material and the carbon steel material to obtain molten wear-resistant material and carbon steel material;

Step 2: pouring the molten wear-resistant material at the first temperature from the bottom of the sand mold into the sand mold through the bottom return pouring system, so that the bottom of the sand mold is filled with the molten wear-resistant material;

Step 3: pour the molten carbon steel material of the second temperature from the top of the sand mold into the sand mold through the rain pouring system, so that the molten carbon steel material and the molten wear-resistant material are mutually melted and combined, and poured until the molten carbon steel material is full Riser, the molten carbon steel material in the riser feeds the casting in the sand mold, and after cooling, a liner blank with a metallurgical combination of the wear-resistant layer and the carbon steel layer is obtained;

Step 4: Cut and remove the risers and runners on the liner blank, and perform overall heat treatment on the blank to obtain a coal grinding liner;

Step 5: Cut the coal grinding liner into pieces, and machine the carbon steel layer of each coal grinding liner to meet the matching requirements of the coal grinding machine.

In one of the implementations, in the manufacturing method of the coal grinding liner provided in the embodiment of the present application, the time when the molten carbon steel material starts pouring in the third step is the same as the time when the molten wear-resistant material is poured in the second step. The interval between times does not exceed 1 minute.

In one of the implementation manners, the first temperature is 1380-1430°C in the manufacturing method of the coal grinding liner provided in the examples of the present application.

In one of the implementation manners, the second temperature is 1500-1520° C. in the manufacturing method of the coal grinding liner provided in the examples of the present application.

In one of the implementation manners, in the method for manufacturing the coal grinding liner provided in the embodiment of the present application, the wear-resistant material is high-chromium cast iron.

In one of the implementations, in the method for manufacturing a coal grinding liner provided in the examples of this application, the carbon steel material is ZG25 carbon steel.

In one of the implementations, in the manufacturing method of the coal grinding liner provided in the embodiment of the present application, the heat treatment of the liner blank in the step 4 includes: heating the liner blank to 960-1000°C, holding the temperature for 1-8 Hours; then slowly cool to 700-750°C, keep warm for 4-10 hours; then slowly cool to below 600°C and take out the oven for air cooling or furnace cooling.

The beneficial effects of the present invention are: adopting the composite casting method, the materials of the wear-resistant layer and the carbon steel layer are simultaneously smelted and poured at the same time, and the metallurgical combination of the two materials is realized at high temperature, the production efficiency is high, and the overall quality of the wear-resistant layer is good. It avoids metallurgical defects caused by repeated fusion during surfacing welding, such as cracks, slag inclusions and pores, etc. After a certain standard heat treatment, that is, "quenching + softening annealing" heat treatment, the hardness of the wear-resistant layer meets the technical requirements, and finally makes the wear-resistant layer meet the technical requirements. The working life of the coal roller is extended.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present application. Those skilled in the art can also obtain other drawings based on these drawings without any creative effort.

Fig. 1 is the schematic diagram of the sand mold in the manufacturing method of the coal grinding liner provided by the embodiment of the present application;

Fig. 2 is the actual picture of the sand mold in Fig. 1;

Fig. 3 is a schematic diagram of a coal grinding liner in the manufacturing method of the coal grinding liner provided by the embodiment of the present application;

Figure 4 is a real shot of the coal grinding liner in Figure 3;

Fig. 5 is a split view of the coal grinding liner in the manufacturing method of the coal grinding liner provided by the embodiment of the present application;

Fig. 6 is a split real shot of the coal grinding liner in Fig. 5 .

Explanation of reference signs:

10-sand mold;

11- upper box;

12 - lower box;

13- Bottom return pouring system;

14-Rain pouring system;

15 - Riser;

16-liner wood mold;

20- pulverized coal liner;

20a-grinding coal lining plate;

21 - carbon steel layer;

22 - wear layer.

Detailed ways

Coal mills are important equipment in coal-fired units in thermal power plants and power steam boilers in petrochemical plants. The stability of their operation is directly related to the "long, full and stable" production and operation and economic benefits of power plants and petrochemical enterprises.

The coal grinding liner is the core part of the coal mill. The lump coal is rolled, rolled and ground by the coal grinding roller and the liner of the coal mill, and after being turned into powder, it is transported to the boiler by high-pressure airflow. Full combustion can significantly increase the combustion rate of coal, thereby increasing steam pressure and power generation efficiency. While saving energy and increasing efficiency, it can also significantly reduce smoke and dust emissions, which has certain environmental protection significance.

The bottom of the coal grinding liner is made of carbon steel, which has excellent machinability. It is easy to match with the bottom plate after machining. The upper part is a wear-resistant layer with high hardness, which is used for grinding and crushing coal or ore. At present, the coal grinding liner is manufactured by surfacing welding process, that is, a layer of wear-resistant material is surfacing on the processed circular steel plate to form a wear-resistant layer working surface. This manufacturing method requires special welding equipment, and the work efficiency is low. Due to the need for repeated metallurgical melting during the surfacing process, it is easy to produce welding micro-cracks, and the quality of the surfacing layer is difficult to be effectively controlled, which brings hidden dangers to the service life of the workpiece. In actual use, micro-cracks are prone to expand and cause durability. The grinding layer falls off, which seriously affects the service life of the coal grinding roller. According to statistics, the working life of the general surfacing welding manufacturing coal grinding liner is about 10 months, and the manufacturing period of this forming method is long, and the market price is correspondingly high. . Moreover, the wear-resistant layer manufactured by the surfacing process needs to be machined to meet the technical requirements, but due to the high hardness of the wear-resistant layer, it is not convenient for machining.

Based on this, this application proposes a bimetallic composite casting method for coal-grinding lining boards. The composite casting process is used to smelt and cast the wear-resistant layer material and the carbon steel layer material at the same time. The two materials are metallurgically combined at high temperature. high productivity. The overall quality of the wear-resistant layer is good, which avoids the metallurgical defects caused by repeated fusion during surfacing, such as cracks, slag inclusions and pores. After a certain standard heat treatment, that is, "quenching + softening annealing" heat treatment, the hardness of the wear-resistant layer meets the technical requirements, and finally the working life of the coal grinding roller is extended.

In addition, since the wear-resistant layer is cast and formed, no mechanical processing is required, and the processing of the wear-resistant layer is eliminated. Instead, only the carbon steel layer needs to be processed. The carbon steel layer itself has good processing performance. The machine tool can realize processing, so it can reduce processing difficulty and improve processing efficiency.

In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below in conjunction with the drawings in the preferred embodiments of the present application. In the drawings, the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of the application. The embodiments described below by referring to the figures are exemplary, and are intended to explain the present application, and should not be construed as limiting the present application. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

Referring to Figures 1-6, the manufacturing method of the coal grinding liner provided by the embodiment of the present application, the structure of the sand mold 10 used includes an upper box 11 and a lower box 12, and the sand mold 10 is equipped with a bottom return pouring system 13 and rain The pouring pouring system 14 forms a mold cavity through the wooden mold 16 of the liner board. The sprue channel of the bottom return gating system 13 is passed vertically downwards from the upper box 11 to the lower box 12, and then turns upwards to be connected to the bottom of the cavity. The pouring channel of the deluge pouring system 14 passes vertically downwards into the lower case 12 from the upper case 11 and then turns upwards to communicate with the bottom top of the cavity, and the upper case 11 is provided with a riser 15 .

The manufacturing method of the coal grinding liner provided in the embodiment of the present application includes the following steps:

Step 1: Simultaneously smelting the wear-resistant material and the carbon steel material to obtain the wear-resistant material and the carbon steel material in molten state. In the embodiment of this application, high chromium cast iron is used as the wear-resistant material, and ZG25 carbon steel is used as the carbon steel material.

Step 2: pouring molten high-chromium cast iron at a temperature of 1380-1430°C from the bottom of the sand mold 10 into the sand mold 10 through the bottom return pouring system 13, so that the bottom of the sand mold 10 is filled with molten high-chromium cast iron, and the pouring quality of the high-chromium cast iron is The quality of the wear-resistant layer 22 that needs to be produced;

Step 3: Pour molten ZG25 carbon steel at a temperature of 1500-1520°C from the top of sand mold 10 into sand mold 10 through the rain pouring system 14, so that the molten ZG25 carbon steel and molten high-chromium cast iron are mutually melted and combined, and poured to Molten ZG25 carbon steel fills the riser 15. Since the thermal joint of the riser 15 is greater than that of the coal grinding liner 20, the riser 15 is finally solidified relative to the liner body, so the molten ZG25 carbon steel in the riser 15 can be The castings in the sand mold 10 are fed and cooled to obtain the liner blank metallurgically combined with the wear-resistant layer 22 and the carbon steel layer 21. The pouring quality of ZG25 carbon steel is the weight of the required carbon steel layer 21 and riser 15. Sum. The solidification sequence of the entire coal grinding liner 20 is as follows: the wear-resistant material poured first solidifies to form the wear-resistant layer 22, followed by the solidification of the carbon steel material to form the carbon steel layer 21, and finally the riser 15 feeds the carbon steel layer 21 and finally solidification.

In addition, since the wear-resistant material is high-chromium cast iron with a low melting point, and the carbon steel material is ZG25 carbon steel with a high melting point, the tapping temperature of carbon steel is about 200°C higher than that of high-chromium cast iron, and the wear-resistant material is located at the bottom , the carbon steel material is located on the upper part, so that the carbon steel layer 21 can be used to feed the wear-resistant layer 22 .

In actual production, it was found that the pouring temperature of ZG25 carbon steel was too high, although it was beneficial to the overall feeding, but it would cause sticky sand defects, and the castings were not easy to clean. Under the premise of ensuring that the carbon steel layer 21 does not stick to sand, the pouring temperature of the high-chromium cast iron should be as high as possible, and the pouring interval of the two materials should be as short as possible, so as to avoid the solidification of the high-chromium cast iron at the bottom when the carbon steel is poured. The upper carbon steel cannot liquid feed the lower high chromium cast iron.

Therefore, after many times of field practice, it is concluded that the tapping temperature of high-chromium cast iron is controlled at 1480-1500°C, and the actual pouring temperature is controlled at 1380-1430°C. The tapping temperature of ZG25 carbon steel is controlled at 1640-1620°C, and the actual pouring temperature is controlled at 1500-1520°C. In order to realize pouring in the above temperature range, the time interval between two pourings should not exceed 1 minute (generally, the temperature drops by about 100°C in 1 minute after tapping). At such a temperature, the ZG25 carbon steel will not cause sand sticking defects due to excessive temperature, and the hardness of the wear-resistant layer 22 will decrease due to excessive mutual melting, and the hardness of the carbon steel layer 21 will increase.

Step 4: Cut and remove the risers 15 and runners on the liner blank, and perform overall heat treatment on the blank after finishing treatment to obtain the coal grinding liner 20 (see Fig. 3 and Fig. 4 ).

Among them, the heat treatment adopts "quenching + softening annealing", specifically: heating the liner blank to 960-1000°C and keeping it warm for 1-8 hours. Then slowly cool to 700-750°C, keep warm for 4-10 hours; then slowly cool to below 600°C and take out the furnace for air cooling or furnace cooling. After heat treatment, the hardness of the wear-resistant layer 22 of the workpiece reaches above HRC56, so that the wear-resistant layer 22 of the workpiece has both Good hardness, but also has a certain toughness to prevent brittle fall off.

After testing, the metallographic structure of the wear-resistant layer 22 is eutectic carbide M7C3+secondary carbide+martensite+retained austenite. Two kinds of materials are casted at the same time to replace the surfacing manufacturing process. The wear-resistant layer 22 is integrally formed after smelting and pouring. The internal quality is better than that of surfacing, and there are few metallurgical defects such as cracks, slag inclusions and pores. The production efficiency of composite casting is obviously better than that of surfacing. Welding production efficiency.

Step 5: According to the technical requirements, the coal-grinding liner 20 is cut into pieces (see Figures 5 and 6), and the carbon steel layer 21 of each coal-milling liner 20a is machined so that the coal-milling liner 20 is It meets the matching requirements of the coal mill. Compared with the whole coal-grinding liner 20 , processing in blocks is more convenient, and facilitates the subsequent installation of the coal-milling liner 20 in blocks.

In addition, since the wear-resistant layer 22 is cast and formed, no mechanical processing is required, and the processing of the wear-resistant layer 22 is eliminated, but only the carbon steel layer 21 needs to be processed, and the carbon steel layer 21 itself has good processing performance , It can be processed with general machine tools, so it can reduce the processing difficulty and improve the processing efficiency.

In the description of the embodiments of the present application, it should be understood that, unless otherwise specified and limited, the terms "installation", "connection", and "connection" should be interpreted in a broad sense, for example, it can be fixed connection, or it can be An indirect connection through an intermediary may be an internal communication between two elements or an interaction relationship between two elements. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application according to specific situations. The orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer" etc. is based on The orientation or positional relationship shown in the drawings is only for the convenience of describing the present application and simplifying the description, and does 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 cannot be understood as Limitations on this Application. In the description of the present application, "plurality" means two or more, unless otherwise specified precisely.

The terms "first", "second", "third", "fourth" and the like in the description and claims of the present application and the above drawings are used to distinguish similar objects, but not necessarily to describe specific sequence or sequence. It is to be understood that the data so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein, for example, can be practiced in sequences other than those illustrated or described herein. Furthermore, the terms "comprising" and "having", as well as any variations thereof, are intended to cover a non-exclusive inclusion, for example, a process, method, system, product or device comprising a sequence of steps or elements is not necessarily limited to the expressly listed instead, may include other steps or elements not explicitly listed or inherent to the process, method, product or apparatus.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present application. scope.

Claims (7)

1. A manufacturing method of a coal grinding liner, comprising the steps of: Step 1: Simultaneously smelting the wear-resistant material and the carbon steel material to obtain molten wear-resistant material and carbon steel material; Step 2: pouring the molten wear-resistant material at the first temperature from the bottom of the sand mold into the sand mold through the bottom return pouring system, so that the bottom of the sand mold is filled with the molten wear-resistant material; Step 3: pour the molten carbon steel material of the second temperature from the top of the sand mold into the sand mold through the rain pouring system, so that the molten carbon steel material and the molten wear-resistant material are mutually melted and combined, and poured until the molten carbon steel material is full Riser, the molten carbon steel material in the riser feeds the casting in the sand mold, and after cooling, a liner blank with a metallurgical combination of the wear-resistant layer and the carbon steel layer is obtained; Step 4: Cut and remove the risers and runners on the liner blank, and perform overall heat treatment on the blank to obtain a coal grinding liner; Step 5: Cut the coal grinding liner into pieces, and machine the carbon steel layer of each coal grinding liner to meet the matching requirements of the coal grinding machine. 2. The manufacturing method of the coal grinding liner according to claim 1, characterized in that, the time when the molten carbon steel material starts pouring in the step 3 and the time when the molten wear-resistant material pouring is completed in the step 2 The interval between them should not exceed 1 minute. 3. The method for manufacturing a coal grinding liner according to claim 1, wherein the first temperature is 1380-1430°C. 4. The method for manufacturing a coal grinding liner according to claim 1, characterized in that the second temperature is 1500-1520°C. 5. The method for manufacturing a coal grinding liner according to claim 1, wherein the wear-resistant material is high chromium cast iron. 6. The manufacturing method of coal grinding liner according to claim 1, characterized in that, the carbon steel material is ZG25 carbon steel. 7. The method for manufacturing a coal grinding liner according to any one of claims 1-6, wherein the heat treatment of the liner blank in step 4 includes: heating the liner blank to 960-1000°C, Keep warm for 1-8 hours; then slowly cool to 700-750°C, keep warm for 4-10 hours; then slowly cool to below 600°C and take out of the oven for air cooling or furnace cooling.

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