Wear-resistant device for striking wheel of coal mill and preparation method of wear-resistant device

Abstract

The invention belongs to the technical field of coal mills, and particularly relates to a coal mill striking wheel wear-resistant device and a preparation method thereof. The wear-resistant device for the striking wheel of the coal mill comprises a manganese steel base material and a wear-resistant layer welded on the surface of the manganese steel base material, and the wear-resistant layer comprises a manganese element and a chromium element. The coal mill striking wheel wear-resisting device has the beneficial effects that the coal mill striking wheel wear-resisting device contains manganese elements and chromium elements and has high impact resistance and wear resistance and long service life, the service life of the coal mill striking wheel wear-resisting device is prolonged to 2000 h from 1000 h compared with a traditional coal mill striking wheel, the reliability of equipment is improved, maintenance manpower and material resources are reduced, the maintenance cost is reduced, and the service life of the coal mill striking wheel wear-resisting device is prolonged. And the maintenance operation risk is reduced, and the production cost is greatly reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of coal mills, and particularly relates to a coal mill impact wheel wear-resistant device and a preparation method thereof. BACKGROUND

[0002] In recent years, due to the influence of factors such as gangue and sundries in incoming coal, the existing impact wheel protection device has poor tolerance to coal types, and in the use process, the wear-resistant layer of the impact wheel protection device locally falls off, causing insufficient output of the coal mill and leading to intensified vibration of the bearing of the coal mill. The operation cycle of the existing coal mill is averagely 1000h, and because the operation cycle is relatively short, a large amount of manpower and material resources need to be invested in the maintenance of the pulverizing system, thus causing problems such as frequent fan coal mill maintenance work, high risk, heavy task and high maintenance cost. SUMMARY

[0003] The application provides a coal mill impact wheel wear-resistant device and a preparation method thereof, and aims to solve the problems of poor wear resistance and relatively short service life of the existing coal mill impact wheel.

[0004] The first aspect of the application provides a coal mill impact wheel wear-resistant device, which comprises a manganese steel base material and a wear-resistant layer welded on the surface of the manganese steel base material.

[0005] The wear-resistant layer comprises manganese elements and chromium elements.

[0006] According to some embodiments of the coal mill impact wheel wear-resistant device provided in the application, the thickness of the wear-resistant layer is 18-20mm.

[0007] According to some embodiments of the coal mill impact wheel wear-resistant device provided in the application, the content of the Mn element in the wear-resistant layer is 11wt%-14wt%.

[0008] According to some embodiments of the coal mill impact wheel wear-resistant device provided in the application, the content of the Cr element in the wear-resistant layer is 10wt%-12wt%.

[0009] The second aspect of the application provides a preparation method of the coal mill impact wheel wear-resistant device according to the first aspect of the application, which comprises the following steps:

[0010] (1) preheating the manganese steel base material;

[0011] (2) using a welding wire containing manganese elements and chromium elements to perform multi-pass welding on the surface of the preheated manganese steel base material to form a coal mill impact wheel wear-resistant device containing a wear-resistant layer.

[0012] According to some embodiments of the preparation method of the coal mill impact wheel wear-resistant device provided in the application, in step (1), the preheating temperature is 50-100℃, and the preheating time is 15-30min.

[0013] According to some embodiments of the preparation method of the coal mill hammer wheel wear-resistant device, the manganese element is derived from manganese metal and / or manganese compounds.

[0014] According to some embodiments of the preparation method of the coal mill hammer wheel wear-resistant device, the manganese element is derived from manganese metal.

[0015] According to some embodiments of the preparation method of the coal mill hammer wheel wear-resistant device, the chromium element is derived from chromium metal and / or chromium compounds.

[0016] According to some embodiments of the preparation method of the coal mill hammer wheel wear-resistant device, the chromium element is derived from chromium metal.

[0017] According to some embodiments of the preparation method of the coal mill hammer wheel wear-resistant device, the welding method includes gas shielded welding.

[0018] According to some embodiments of the preparation method of the coal mill hammer wheel wear-resistant device, the protective gas used in the gas shielded welding includes carbon dioxide and argon in a volume ratio of 1: (3-4).

[0019] According to some embodiments of the preparation method of the coal mill hammer wheel wear-resistant device, the welding includes multi-layer repeated welding.

[0020] According to some embodiments of the preparation method of the coal mill hammer wheel wear-resistant device, the thickness of the wear-resistant layer obtained by each layer of welding is ≤4mm.

[0021] According to some embodiments of the preparation method of the coal mill hammer wheel wear-resistant device, the welding current is 180-220A, the welding voltage is 24-28V, and the welding temperature is 180-200℃.

[0022] According to some embodiments of the preparation method of the coal mill hammer wheel wear-resistant device, the preparation method of the coal mill hammer wheel wear-resistant device further includes cooling treatment of the product after welding.

[0023] According to some embodiments of the preparation method of the coal mill hammer wheel wear-resistant device, the cooling treatment includes natural cooling.

[0024] The beneficial effects of the present application include that the coal mill hammer wheel wear-resistant device contains manganese and chromium elements, has high impact resistance, wear resistance and long service life, and the service life of the traditional coal mill hammer wheel is increased from 1000h to 2000h, which improves the reliability of the equipment, reduces the labor and material of maintenance, reduces the risk of maintenance operation, and greatly reduces the production cost. DETAILED DESCRIPTION

[0025] Embodiments of the present application are described in detail below, examples of which are exemplary and intended to explain the present application, and are not to be understood as limiting the present application.

[0026] In the present application, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative expressions of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0027] The embodiment of the present application provides a coal mill hitting wheel wear-resistant device, which comprises a manganese steel base material and a wear-resistant layer welded on the surface of the manganese steel base material; the wear-resistant layer comprises manganese elements and chromium elements.

[0028] The coal mill hitting wheel wear-resistant device described in the present application upgrades the chemical composition of the hitting wheel on the premise of retaining the original design size of the coal mill hitting wheel, and improves the strength of the manganese steel base material. The manganese elements and the chromium elements are added in the hitting wheel, so that the hitting wheel contains the manganese elements and the chromium elements. Since the manganese elements and the chromium elements have good tensile strength and impact absorption energy performance, the tensile strength of the coal mill hitting wheel wear-resistant device is greater than or equal to 735Mpa, and the impact absorption energy is greater than or equal to 80J.

[0029] The coal mill hitting wheel wear-resistant device described in the present application adopts a double-alloy process fusion casting, which guarantees high wear resistance and sufficient toughness buffer to impact of impurities in coal, ensures that the wear-resistant layer of the hitting wheel will not fall off, and improves the service life of the hitting wheel.

[0030] In some embodiments of the present application, the thickness of the wear-resistant layer is 18-20mm; for example, 18mm, 18.5mm, 19mm, 19.6mm, 20mm, etc.

[0031] In some embodiments of the present application, the content of the Mn element in the wear-resistant layer is 11wt%-14wt%; for example, 11wt%, 12wt%, 12.5wt%, 13.2wt%, 14wt%, etc.

[0032] In some embodiments of the present application, the content of Cr element in the wear-resistant layer is 10wt%-12wt%, such as 10wt%, 10.5wt%, 11.2wt%, 11.5wt%, 12wt% and the like.

[0033] If only Mn element is added, it will lead to poor hardening effect of the wear-resistant layer in static wear. Chromium element can form chromium carbide (such as Cr7C3 or Cr 23 C6) with carbon, and the hardness can reach 1200HV-1800HV, which can greatly improve the wear resistance of the wear-resistant layer.

[0034] Although the carbon element in the manganese steel base material can form carbide with chromium or manganese to improve the hardness of the base material, if the chromium element and the manganese element are added in excess, the toughness will be reduced. The addition of manganese element makes the wear-resistant layer maintain austenitic structure at room temperature, and has high toughness; under impact load, the austenite is transformed into martensite (the surface hardness of the wear-resistant layer increases from 200HB to 500HB).

[0035] The present application also provides a preparation method of the wear-resistant device of the coal mill impact wheel according to the first aspect of the present application, comprising the following steps:

[0036] (1) preheating the manganese steel base material;

[0037] (2) using a welding wire containing manganese element and chromium element to perform multi-pass welding on the surface of the preheated manganese steel base material to form a wear-resistant device of the coal mill impact wheel containing a wear-resistant layer.

[0038] In some embodiments of the present application, in step (1), the preheating temperature is 50-100℃, such as 50℃, 65℃, 78℃, 83℃, 95℃ and the like, and the preheating time is 15-30min, such as 15min, 18min, 22min, 27min, 30min and the like.

[0039] In some embodiments of the present application, the manganese element is derived from metallic manganese and / or manganese compounds.

[0040] In some embodiments of the present application, the manganese element is derived from metallic manganese.

[0041] In some embodiments of the present application, the chromium element is derived from metallic chromium and / or chromium compounds.

[0042] In some embodiments of the present application, the chromium element is derived from metallic chromium.

[0043] In some embodiments of the present application, the welding method includes gas shielded welding.

[0044] In some embodiments of the present application, the protective gas used in the gas shielded welding includes carbon dioxide and argon in a volume ratio of 1:3-4. During the welding process, the welding quality needs to be strictly controlled, and the invasion of air needs to be minimized to prevent the generation of pores.

[0045] In some embodiments of the present application, the welding includes multi-layer repeated welding; during the welding process, a plurality of welds form a wear-resistant layer, the thickness of the wear-resistant layer obtained by each welding is ≤4 mm, and repeated welding obtains a wear-resistant layer with a thickness of 18-20 mm. During the welding process, after each weld is completed, the weld is lightly struck with a round hammer (suitable for thick plates or rigid structures) to eliminate residual stress. The use of this welding method improves the toughness and wear resistance of the wear-resistant layer of the impact wheel wear-resistant device.

[0046] In some embodiments of the present application, the welding current is 180-220 A, for example, 180 A, 190 A, 200 A, 210 A, 220 A, etc., the welding voltage is 24-28 V, for example, 24 V, 25 V, 26 V, 28 V, etc., and the welding temperature is 180-200℃, for example, 180℃, 185℃, 193℃, 196℃, 200℃, etc. The welding temperature is controlled at 180-200℃ to avoid embrittlement caused by high-temperature residence.

[0047] In some embodiments of the present application, the method for preparing the impact wheel wear-resistant device of the coal mill further includes cooling treatment of the product after welding.

[0048] In some embodiments of the present application, the cooling treatment includes natural cooling.

[0049] The technical solutions of the present application will be further described below in combination with specific embodiments.

[0050] Embodiment 1

[0051] A method for preparing an impact wheel wear-resistant device of a coal mill includes the following steps:

[0052] A manganese steel base material (ZGMn 13 ) is preheated for 20 min in an environment with a temperature of 60℃; YD256 welding wire (the content of manganese element in the welding wire is 11wt%, and the mass content of chromium element is 12wt%) is used for gas shielded welding on the surface of the preheated manganese steel base material (the protective gas used is carbon dioxide and argon in a volume ratio of 1:4), the welding current is 180 A, and the voltage is 25 V; after each weld is completed, the weld is lightly struck with a round hammer, a plurality of welds form a wear-resistant layer with a thickness of 3 mm, when the temperature of the wear-resistant layer reaches below 200℃ (180℃ in this embodiment), repeated welding is performed to form a wear-resistant layer with a thickness of 18 mm, after the welding is completed, natural cooling is performed, and the impact wheel wear-resistant device of the coal mill is obtained.

[0053] Example 2

[0054] The difference between the preparation method of the coal mill impact wheel wear-resistant device according to the embodiment 2 and the embodiment 1 is that the content of the manganese element in the YD256 welding wire is 9wt% during the preparation process of the coal mill impact wheel wear-resistant device according to the embodiment 2.

[0055] The specific operation steps include:

[0056] The manganese steel base material (ZGMn 13 ) is preheated for 20 minutes in an environment with a temperature of 60℃; the YD256 welding wire (the content of the manganese element in the welding wire is 9wt%, and the mass content of the chromium element is 12wt%) is used for gas shielded welding on the surface of the preheated manganese steel base material (the protective gas used is carbon dioxide and argon with a volume ratio of 1:4), the welding current is 180A, and the voltage is 25V; when each welding pass is completed, the welding seam is lightly hit with a round head hammer, and a plurality of welding passes form a wear-resistant layer with a thickness of 3mm; when the temperature of the wear-resistant layer reaches below 200℃ (180℃ in this embodiment), repeated welding is performed to form a wear-resistant layer with a thickness of 18mm; after the welding is completed, the wear-resistant layer is naturally cooled to obtain the coal mill impact wheel wear-resistant device.

[0057] Example 3

[0058] The difference between the preparation method of the coal mill impact wheel wear-resistant device according to the embodiment 3 and the embodiment 1 is that the content of the manganese element in the YD256 welding wire is 14wt% during the preparation process of the coal mill impact wheel wear-resistant device according to the embodiment 3.

[0059] Example 4

[0060] The difference between the preparation method of the coal mill impact wheel wear-resistant device according to the embodiment 4 and the embodiment 1 is that the content of the manganese element in the YD256 welding wire is 16wt% during the preparation process of the coal mill impact wheel wear-resistant device according to the embodiment 4.

[0061] Example 5

[0062] The difference between the preparation method of the coal mill impact wheel wear-resistant device according to the embodiment 5 and the embodiment 1 is that the content of the chromium element in the YD256 welding wire is 10wt% during the preparation process of the coal mill impact wheel wear-resistant device according to the embodiment 5.

[0063] The specific operation steps include:

[0064] The manganese steel base material (ZGMn 13) is placed in an environment with a temperature of 60°C for preheating treatment for 20 min; YD256 welding wire (the content of manganese element in the welding wire is 11wt%, the content of chromium element is 10wt%) is used for gas shielded welding on the surface of the preheated manganese steel base material (the protective gas used is carbon dioxide and argon with a volume ratio of 1:4), the welding current is 180A, the voltage is 25V, when each welding pass is completed, the weld is lightly hit with a round head hammer, and multiple welding passes form a wear-resistant layer with a thickness of 3mm, when the temperature of the wear-resistant layer reaches below 200°C (180°C in this embodiment), repeated welding is performed to form a wear-resistant layer with a thickness of 18mm, after welding is completed, natural cooling is performed, and the coal mill impact wheel wear-resistant device is obtained.

[0065] Example 6

[0066] The difference between the preparation method of the coal mill impact wheel wear-resistant device in Example 6 and Example 1 is only that the content of chromium element in the YD256 welding wire in the preparation process of the coal mill impact wheel wear-resistant device in Example 6 is 8wt%.

[0067] Example 7

[0068] The difference between the preparation method of the coal mill impact wheel wear-resistant device in Example 7 and Example 1 is only that the content of chromium element in the YD256 welding wire in the preparation process of the coal mill impact wheel wear-resistant device in Example 7 is 15wt%.

[0069] Comparative Example 1

[0070] The difference between the preparation method of the coal mill impact wheel wear-resistant device in Comparative Example 1 and Example 1 is only that the welding wire does not contain manganese element in the preparation process of the coal mill impact wheel wear-resistant device in Comparative Example 1.

[0071] The specific operation steps include:

[0072] The manganese steel base material (ZGMn 13 ) is placed in an environment with a temperature of 60°C for preheating treatment for 20 min; YD256 welding wire (the content of chromium element in the welding wire is 12wt%) is used for gas shielded welding on the surface of the preheated manganese steel base material (the protective gas used is carbon dioxide and argon with a volume ratio of 1:4), the welding current is 180A, the voltage is 25V, when each welding pass is completed, the weld is lightly hit with a round head hammer, and multiple welding passes form a wear-resistant layer with a thickness of 3mm, when the temperature of the wear-resistant layer reaches below 200°C (180°C in this embodiment), repeated welding is performed to form a wear-resistant layer with a thickness of 18mm, after welding is completed, natural cooling is performed, and the coal mill impact wheel wear-resistant device is obtained.

[0073] Comparative Example 2

[0074] The preparation method of the mill hammer wheel wear-resistant device of Comparative Example 2 is different from that of Example 1 only in that the welding wire does not contain chromium element in the preparation process of the mill hammer wheel wear-resistant device of Comparative Example 2.

[0075] The specific operation steps include:

[0076] The manganese steel base material (ZGMn 13 ) is preheated for 20 min in an environment with a temperature of 60°C; YD256 welding wire (the content of manganese element in the welding wire is 11wt%) is used for gas shielded welding on the surface of the preheated manganese steel base material (the protective gas used is carbon dioxide and argon with a volume ratio of 1:4), the welding current is 180A, and the voltage is 25V; when each welding pass is completed, the welding seam is lightly hit with a round head hammer, and a plurality of welding passes form a wear-resistant layer with a thickness of 3mm; when the temperature of the wear-resistant layer reaches below 200°C (180°C in this example), repeated welding is performed to form a wear-resistant layer with a thickness of 18mm; after welding is completed, natural cooling is performed to obtain the mill hammer wheel wear-resistant device.

[0077] Performance research of the mill hammer wheel wear-resistant devices of Examples 1-7 and Comparative Examples 1-2

[0078] Test method: the mill hammer wheel wear-resistant devices of Examples 1-7 and Comparative Examples 1-2 are tested for service life of the wear-resistant layer under the condition of 500r / min, and the results are shown in Table 1.

[0079] Table 1

[0080]

[0081]

[0082] As can be seen from Table 1, the service life of the mill hammer wheel wear-resistant device of the present application under the condition of 500r / min can reach 2000h, which is much higher than the service life of 1000h of the existing mill hammer wheel wear-resistant device. If 68 sets of hammer wheel protective devices are used per year, only 34 sets of hammer wheel protective devices are needed to be used per year if the mill hammer wheel wear-resistant device of the present application is used instead of the traditional mill hammer wheel, and the cost of each set of hammer wheel protective device is 50,000 yuan, which can save 1.7 million yuan per year.

[0083] As can be seen from Comparative Examples 1-4, when the content of manganese element in the wear-resistant layer of the mill hammer wheel wear-resistant device is 11wt%-14wt%, the service life of the wear-resistant layer obtained is longer.

[0084] As can be seen from Comparative Example 1 and Examples 5-7, when the content of chromium element in the wear-resistant layer of the wear-resistant device of the coal mill impact wheel is 10wt%-12wt%, the service life of the wear-resistant layer obtained is longer.

[0085] Although the above-mentioned embodiments have been shown and described, it is to be understood that the above-mentioned embodiments are exemplary and are not to be construed as limiting the present application, and any changes, modifications, replacements and variations made by those of ordinary skill in the art to the above-mentioned embodiments are within the protection scope of the present application.

Claims

1. A coal mill beater wheel wear protection device characterised in that, The wear-resistant layer comprises manganese and chromium elements. The content of the Mn element in the wear-resistant layer is 11wt%-14wt%, and the content of the Cr element in the wear-resistant layer is 10wt%-12wt%.

2. The coal mill beater wheel wear protection device of claim 1, wherein, The thickness of the wear-resistant layer is 18-20mm.

3. The method of manufacturing a wear assembly for a coal pulverizer beater wheel as defined in any one of claims 1-2, wherein, The method comprises the following steps: (1) preheating the manganese steel base material; (2) performing multi-pass welding on the surface of the preheated manganese steel base material by using a welding wire containing manganese and chromium elements to form a wear-resistant device for a coal mill impact wheel.

4. The method of claim 3, wherein the method further comprises the step of: In step (1), the preheating temperature is 50-100℃, and the preheating time is 15-30min. ​ 5. The method of claim 3, wherein the method further comprises the step of: The manganese element is derived from manganese metal and / or a manganese compound; ​ The chromium element is derived from chromium metal and / or a chromium compound.

6. The method of claim 3, wherein the method further comprises the step of: The welding method comprises gas shielded welding. ​ The protective gas used in the gas shielded welding comprises carbon dioxide and argon in a volume ratio of 1:(3-4).

7. The method of claim 3, wherein the method further comprises the step of: The welding comprises multi-layer repeated welding, and the thickness of the wear-resistant layer obtained by each layer of welding is ≤4mm. ​ 8. The method of claim 3, wherein the method further comprises the step of: 5 providing a plurality of wear plates having a plurality of wear elements attached thereto. The welding current is 180-220A, the welding voltage is 24-28V, and the welding temperature is 180-200℃.

9. The method of claim 3, wherein the method further comprises the steps of: providing a plurality of wear plates; and attaching the plurality of wear plates to the plurality of arms. The method for preparing the wear-resistant device for the coal mill impact wheel further comprises cooling the welded product. The cooling process comprises natural cooling.

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