CN111560532A - Preparation method and application of novel shield tunneling machine scraper - Google Patents
Preparation method and application of novel shield tunneling machine scraper Download PDFInfo
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/05—Mixtures of metal powder with non-metallic powder
- C22C1/051—Making hard metals based on borides, carbides, nitrides, oxides or silicides; Preparation of the powder mixture used as the starting material therefor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/17—Metallic particles coated with metal
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
- B22F3/1003—Use of special medium during sintering, e.g. sintering aid
- B22F3/1007—Atmosphere
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/10—Sintering only
- B22F3/1017—Multiple heating or additional steps
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C29/00—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides
- C22C29/02—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides
- C22C29/06—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds
- C22C29/08—Alloys based on carbides, oxides, nitrides, borides, or silicides, e.g. cermets, or other metal compounds, e.g. oxynitrides, sulfides based on carbides or carbonitrides based on carbides, but not containing other metal compounds based on tungsten carbide
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
- E21D9/00—Tunnels or galleries, with or without linings; Methods or apparatus for making thereof; Layout of tunnels or galleries
- E21D9/06—Making by using a driving shield, i.e. advanced by pushing means bearing against the already placed lining
- E21D9/08—Making by using a driving shield, i.e. advanced by pushing means bearing against the already placed lining with additional boring or cutting means other than the conventional cutting edge of the shield
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
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- B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
- B22F2005/001—Cutting tools, earth boring or grinding tool other than table ware
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
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Abstract
The invention discloses a preparation method of a novel shield machine scraper, which comprises the steps of coating a cobalt metal layer on the surface of tungsten carbide powder with the particle size of 4-6 mu m by adopting a novel powder coating technology-chemical plating method, and uniformly mixing the obtained WC-Co composite powder with a certain amount of additives to obtain WC-Cr3C2Preparing WC-Cr from-TaC-Co composite powder by a vacuum sintering process3C2-TaC-Co cemented carbide tool bit, finally welded by medium and high frequency inductionThe technique is to use silver-based solder as a brazing connecting material to carry out the brazing of WC-Cr3C2the-TaC-Co hard alloy cutter head is fixedly arranged on a cutter base body made of 42CrMo steel. The cutting tool device designed by the invention has a simple structure, the preparation technology of the hard alloy powder material is novel, the cutting performance, the structural strength, the wear resistance and the shock resistance of the shield cutter can be improved, the service life of the shield cutter can be effectively prolonged, and the cutting tool device has a good application prospect in the direction of the shield cutter.
Description
Technical Field
The invention belongs to the field of material processing engineering, and particularly relates to a preparation method and application of a novel shield tunneling machine scraper.
Background
With the increasing scale of urban rail transit construction in China, the shield construction technology is more and more important in the construction of urban subways, railway and highway traffic, energy transmission, underground tunnels and other heavy projects due to the reliability, safety and high efficiency of the shield construction technology. When the shield machine is pushed forwards, the scraper generates axial shearing force and radial cutting force on the soil body on the excavation surface along with the rotation of the cutter head, and the cutting edge and the cutter head part are inserted into the stratum under the rotation of the cutter head to continuously cut the soil body in front of excavation. The edge scraper and the front scraper pay special attention to the wear resistance and simultaneously give consideration to the impact resistance. Therefore, by discussing the wear mechanism of the shield cutter, corresponding solution suggestions are further provided, and new material cutter heads are researched and designed, so that the method has very important engineering significance on the shield technology.
Cemented carbide is an alloy material made of hard phase (high hardness, refractory metal carbide powder, such as WC, TiC, etc.) by using Co, Fe, Ni, etc. as binder phase through powder metallurgy process. The hard alloy has high hardness, good strength and toughness, and excellent wear resistance, heat resistance and other properties, so that the hard alloy has the reputation of industrial teeth. The tool bit of the traditional shield cutter used in the current engineering is made of WC-Co hard alloy by a mechanical ball milling method, while the WC-Co composite hard alloy tool bit coated and synthesized by a chemical plating surface treatment process is adopted in the invention. The tungsten carbide-based hard alloy cutter material is prepared by a vacuum sintering method by Zhilan and the like, and the influence of different modification methods on the structure and the performance of the tungsten carbide-based hard alloy cutter material is researched, and the result shows that the relative density, the hardness, the compressive strength and the wear resistance of the hard alloy cutter material can be effectively improved by chemically plating and coating the bonding metal cobalt on the surface of the tungsten carbide; zhu et al used a new chemical plating process, plating a layer of cobalt metal on the tungsten carbide powder, coating the composite WC-Co composite powder on the steel surface with laser, studied the influence of the operating parameters on the WC-Co coating, and compared with the wear resistance of the industrial WC-Co powder coating, the results showed that the coating using the novel composite WC-Co powder had good texture and good wear resistance; the cobalt metal layer is coated on the surface of the tungsten carbide particles by adopting a low-temperature chemical plating method and ultrasonic-assisted chemical plating respectively by Zhuliu, Wangjinfang and the like, and the result shows that the metal cobalt distributed along the grain boundary of the tungsten carbide not only plays a role of a binder, but also plays a role of an inhibitor to hinder the growth of the grains, the sintered alloy grains are uniformly distributed, and the hardness and the fracture toughness are also effectively improved; the influence of additives TiC and TaC on the relevant performance of the WC-Co hard alloy cutter head is researched by Wangzhou and the like, and the research result shows that the structural Hardness (HRA) of the treated cutter head can reach 87 which is far higher than 65 of the national standard for the cutter head of a coal mining machine, and the fracture toughness is also improved. At present, the research on preparing WC-Co hard alloy by a chemical plating method mostly stays in the research stage of a laboratory, but the research on really using the WC-Co hard alloy prepared by the chemical plating method in engineering practice is few, and the bit material of the shield cutter head is formed by sintering WC-Co hard alloy powder prepared by the chemical plating method and adding a proper amount of additives (chromium carbide and tantalum carbide).
The existing shield cutter has various structures so as to realize high cutting force and high bonding strength. The optimal design of the shield cutter is an important factor for determining the working capacity of the shield machine.
Disclosure of Invention
The purpose of the invention is as follows: in order to solve the technical problems in the prior art, the invention aims to provide a preparation method of a shield machine scraper, so that the wear resistance and the shock resistance of a scraper cutter in the propelling process of a shield machine are improved, the working efficiency of the shield machine is improved, and the service life of the shield machine is prolonged.
The technical scheme is as follows: in order to achieve the technical purpose, the invention provides a preparation method of a shield machine scraper, which comprises the following steps:
(1) coating a cobalt metal layer on the surface of tungsten carbide by using tungsten carbide powder as a raw material through a chemical plating surface treatment process to prepare WC-Co composite powder;
(2) adding a certain amount of additive into the WC-Co composite powder obtained in the step (1), and uniformly mixing to obtain WC-Cr3C2-TaC-Co composite powder, wherein the additives are chromium carbide and tantalum carbide;
(3) WC-Cr obtained in step (2)3C2After glue blending, granulation and cold press molding, the-TaC-Co composite powder is subjected to vacuum sintering in a vacuum furnace to prepare WC-Cr3C2-TaC-Co cemented carbide, which is cut to form the design insert;
(4) the WC-Cr prepared in the step (3)3C2The TaC-Co hard alloy tool bit is fixedly arranged on the tool base body.
In the step (1), the particle size range of the tungsten carbide is 4-6 μm.
In the step (1), the surface treatment process by the chemical plating method is a process method for chemically plating cobalt-coated tungsten carbide based on cobalt salt activation. In one particular embodiment, the method disclosed in patent 2017112500064 may be employed: taking a certain amount of tungsten carbide powder with the average particle size of 4-6 microns, placing the tungsten carbide powder in a certain amount of hydrofluoric acid-nitric acid mixed aqueous solution, and roughening the tungsten carbide powder under the ultrasonic dispersion condition for 30min, wherein the concentration of hydrofluoric acid is 60ml/L, the concentration of nitric acid is 40ml/L, and the roughening time is 30 min. Filtering and drying the powder, and soaking the powder in a cobalt sulfate-sodium hypophosphite activation solution in an ultrasonic dispersion environment, wherein the content of cobalt sulfate heptahydrate and the content of sodium hypophosphite monohydrate in the activation solution are 40g/L and 60min respectively. And then putting the soaked powder into a crucible and heating the powder by using a box furnace, wherein the heating rate is 10 ℃/min, the heat treatment temperature is 180 ℃, and after the heating treatment, the cobalt sulfate-sodium hypophosphite activating solution attached to the surface of the powder can generate a thermal oxidation reduction reaction, so that the surface of the tungsten carbide is activated. And (3) putting the activated powder into a prepared chemical plating solution, wherein the content of cobalt sulfate heptahydrate is 50g/L, the content of sodium hypophosphite monohydrate is 40g/L, the content of sodium citrate dihydrate is 70g/L, the content of boric acid is 25g/L, the pH value is adjusted to 9, the water bath temperature is controlled to be 80 ℃, the rotating speed of a stirring rod is 350r/min, and the plating time is 15 min. And filtering and drying the powder after chemical plating to obtain the tungsten carbide particles with uniform cobalt metal plated on the surfaces.
In the step (1), the mass of Co in the WC-Co composite powder prepared by the chemical plating surface treatment process accounts for 7-9 wt% of the mass of the composite powder.
In the step (2), WC-Cr3C2The mass fraction of chromium carbide in the-TaC-Co composite powder is 0.5-0.7%, and the mass fraction of tantalum carbide is 0.3-0.5%.
In the step (3), the vacuum sintering process comprises the following specific processes: weighing a proper amount of WC-Cr3C2Mixing TaC-Co composite powder and a forming agent in a certain proportion and drying the mixture appropriately, wherein the forming agent is paraffin, granulating the mixture by using a screen, and then putting the mixture into a graphite die for compaction forming, and preferably, the pressure is 100 MPa; and then, placing the graphite mold into a sintering cavity, vacuumizing to about 1-5 Pa, and then, heating and sintering.
Specifically, in the sintering process, the furnace temperature is increased from room temperature to 200 ℃ at the speed of 3 ℃/min, the temperature is kept for 0.5h, then is increased to 470 ℃ at the speed of 2 ℃/min, the temperature is kept for 1.5h, then is increased to 900 ℃ at the speed of 6 ℃/min, the temperature is kept for 30min, then is increased to 1250 ℃ at the speed of 7 ℃/min, the temperature is kept for 30min, and finally is increased to 1450 ℃ at the speed of 2.5 ℃/min, and the temperature is kept for 1 h; and in the cooling stage, the temperature in the furnace is reduced to room temperature in a furnace cooling mode.
In the step (4), the hard alloy cutter head adopts a medium-high frequency induction welding technology, and silver-based brazing filler metal is used as a brazing connecting material and is fixedly arranged on the cutter handle.
The invention further provides an application of the shield tunneling machine scraper prepared from the cutter material.
Has the advantages that: the invention provides a preparation method of a profile shield machine scraper material, which improves the cutting performance and the structural strength of a shield machine scraper cutter, effectively prolongs the service life of the shield machine scraper cutter and has better application prospect in the direction of the shield cutter.
Detailed Description
The following are preferred embodiments of the present invention, which are intended to be illustrative only and not limiting, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Example 1
(1) Taking tungsten carbide powder with the particle size range of 4 mu m as a raw material, and coating a cobalt metal layer on the surface of the tungsten carbide through a chemical plating surface treatment process, wherein the chemical plating surface treatment process comprises the following steps: taking a certain amount of tungsten carbide powder with the average particle size of 4-6 microns, placing the tungsten carbide powder in a certain amount of hydrofluoric acid-nitric acid mixed aqueous solution, and roughening the tungsten carbide powder under the ultrasonic dispersion condition for 30min, wherein the concentration of hydrofluoric acid is 60ml/L, the concentration of nitric acid is 40ml/L, and the roughening time is 30 min. Filtering and drying the powder, and soaking the powder in a cobalt sulfate-sodium hypophosphite activation solution in an ultrasonic dispersion environment, wherein the content of cobalt sulfate heptahydrate and the content of sodium hypophosphite monohydrate in the activation solution are 40g/L and 60min respectively. And then putting the soaked powder into a crucible and heating the powder by using a box furnace, wherein the heating rate is 10 ℃/min, the heat treatment temperature is 180 ℃, and after the heating treatment, the cobalt sulfate-sodium hypophosphite activating solution attached to the surface of the powder can generate a thermal oxidation reduction reaction, so that the surface of the tungsten carbide is activated. And (3) putting the activated powder into a prepared chemical plating solution, wherein the content of cobalt sulfate heptahydrate is 50g/L, the content of sodium hypophosphite monohydrate is 40g/L, the content of sodium citrate dihydrate is 70g/L, the content of boric acid is 25g/L, the pH value is adjusted to 9, the water bath temperature is controlled to be 80 ℃, the rotating speed of a stirring rod is 350r/min, and the plating time is 15 min. And filtering and drying the powder after chemical plating to obtain the tungsten carbide particles with uniform cobalt metal plated on the surfaces.
(2) Uniformly mixing a proper amount of the WC-Co composite powder obtained in the step (1) with a certain amount of chromium carbide and tantalum carbide to obtain WC-Cr3C2-TaC-Co composite powder, wherein the content of chromium carbide is 0.6% and the content of tantalum carbide is 0.4%.
(3) Taking a proper amount of WC-Cr obtained in the step (2)3C2Mixing the-TaC-Co composite powder with a proper amount of forming agent (paraffin)And after being dried properly, the mixture is granulated by a screen, then the mixture is put into a graphite die for compaction forming (the pressure is 100MPa), and a pressure head is placed to complete die assembly. Then placing the die into a sintering cavity and vacuumizing, wherein the vacuum degree is about 1Pa, then starting to heat and sinter, in the sintering process, raising the furnace temperature from room temperature to 200 ℃ at the speed of 3 ℃/min, preserving heat for 0.5h, raising the furnace temperature to 470 ℃ at the speed of 2 ℃/min, preserving heat for 1.5h, raising the furnace temperature to 900 ℃ at the speed of 6 ℃/min, preserving heat for 30min, raising the furnace temperature to 1250 ℃ at the speed of 7 ℃/min, preserving heat for 30min, and finally raising the furnace temperature to 1450 ℃ at the speed of 2.5 ℃/min, preserving heat for 1 h; in the cooling stage, the temperature in the furnace is reduced to room temperature by adopting a furnace cooling mode, and finally WC-Cr is prepared3C2-TaC-Co cemented carbide. And cutting and processing the hard alloy obtained by vacuum sintering into a cutter head with a specific size and shape.
(4) The WC-Cr prepared in the step (3)3C2the-TaC-Co hard alloy tool bit adopts a medium-frequency and high-frequency induction welding technology, silver-based brazing filler metal is used as a brazing connecting material and fixedly arranged on a tool base body, a surfacing wear-resistant layer is arranged on the top of the tool, the thickness of the surfacing wear-resistant layer is 5mm, and the edge of the tool is blunt. Finally, the prepared scraper (14 # cutter in table 1) is installed on a cutter head B spoke of a shield machine used in a subway shield tunneling project and compared with the traditional scraper cutter used in the project (4 # cutter material components and performances in table 1 are shown in table 2) and the scrapers prepared in other embodiments for the practical application performance of the project, and the obtained cutter wear condition statistical table is shown in table 1.
Example 2
(1) The method is characterized in that tungsten carbide powder with the particle size range of 4 mu m is used as a raw material, a cobalt metal layer is coated on the surface of the tungsten carbide through a chemical plating method surface treatment process, the chemical plating method surface treatment process is a process method for chemically plating cobalt to coat the tungsten carbide based on cobalt salt activation, and the specific implementation steps are the same as those in example 1.
(2) Uniformly mixing a proper amount of the WC-Co composite powder obtained in the step (1) with a certain amount of additives (chromium carbide and tantalum carbide) to obtain WC-Cr3C2-TaC-Co composite powder, wherein the content of chromium carbide is 0.8% and the content of tantalum carbide is 0.6%.
(3) GetProper amount of WC-Cr obtained in the step (2)3C2Mixing the-TaC-Co composite powder with a proper amount of forming agent (paraffin), drying the mixture properly, granulating the mixture by using a screen, putting the mixture into a graphite die to perform compaction forming (the pressure is 100MPa), and placing a pressure head to complete die assembly. Then placing the die into a sintering cavity and vacuumizing, wherein the vacuum degree is about 1Pa, then starting to heat and sinter, in the sintering process, raising the furnace temperature from room temperature to 200 ℃ at the speed of 3 ℃/min, preserving heat for 0.5h, raising the furnace temperature to 470 ℃ at the speed of 2 ℃/min, preserving heat for 1.5h, raising the furnace temperature to 900 ℃ at the speed of 6 ℃/min, preserving heat for 30min, raising the furnace temperature to 1250 ℃ at the speed of 7 ℃/min, preserving heat for 30min, and finally raising the furnace temperature to 1450 ℃ at the speed of 2.5 ℃/min, preserving heat for 1 h; in the cooling stage, the temperature in the furnace is reduced to room temperature by adopting a furnace cooling mode, and finally WC-Cr is prepared3C2-TaC-Co cemented carbide. And cutting and processing the hard alloy obtained by vacuum sintering into a tool bit.
(4) The WC-Cr prepared in the step (3)3C2the-TaC-Co hard alloy tool bit adopts a medium-frequency and high-frequency induction welding technology, silver-based brazing filler metal is used as a brazing connecting material and fixedly arranged on a tool base body, a surfacing wear-resistant layer is arranged on the top of the tool, the thickness of the surfacing wear-resistant layer is 5mm, and the edge of the tool is blunt. Finally, the prepared scraper (7 # cutter in the table) is arranged on a cutter head B spoke of a shield machine used in the shield tunneling engineering of the subway, the practical engineering application performance of the prepared scraper is compared with that of a traditional scraper (4 # cutter in the table) used in the engineering and the prepared scrapers of other embodiments, and the obtained cutter wear condition statistical table is shown in table 1.
Example 3:
(1) the method is characterized in that tungsten carbide powder with the particle size range of 4 mu m is used as a raw material, a cobalt metal layer is coated on the surface of the tungsten carbide through a chemical plating method surface treatment process, the chemical plating method surface treatment process is a process method for chemically plating cobalt to coat the tungsten carbide based on cobalt salt activation, and the specific implementation steps are the same as those in example 1.
(2) Uniformly mixing a proper amount of the WC-Co composite powder obtained in the step (1) with a certain amount of additives (chromium carbide and tantalum carbide) to obtain WC-Cr3C2-TaC-Co composite powder, wherein the content of chromium carbide is 0.6% and the content of tantalum carbide is 0.4%。
(3) Taking a proper amount of WC-Cr obtained in the step (2)3C2Mixing the-TaC-Co composite powder with a proper amount of forming agent (paraffin), drying the mixture properly, granulating the mixture by using a screen, putting the mixture into a graphite die to perform compaction forming (the pressure is 100MPa), and placing a pressure head to complete die assembly. Then placing the die into a sintering cavity and vacuumizing, wherein the vacuum degree is about 5Pa, then starting heating and sintering, in the sintering process, raising the furnace temperature from room temperature to 200 ℃ at the speed of 3 ℃/min, preserving heat for 0.5h, raising the furnace temperature to 470 ℃ at the speed of 2 ℃/min, preserving heat for 1.5h, raising the furnace temperature to 900 ℃ at the speed of 6 ℃/min, preserving heat for 30min, raising the furnace temperature to 1250 ℃ at the speed of 7 ℃/min, preserving heat for 30min, and finally raising the furnace temperature to 1450 ℃ at the speed of 2.5 ℃/min, preserving heat for 1 h; in the cooling stage, the temperature in the furnace is reduced to room temperature by adopting a furnace cooling mode, and finally WC-Cr is prepared3C2-TaC-Co cemented carbide. And cutting and processing the hard alloy obtained by vacuum sintering into a tool bit.
(4) The WC-Cr prepared in the step (3)3C2the-TaC-Co hard alloy tool bit adopts a medium-frequency and high-frequency induction welding technology, silver-based brazing filler metal is used as a brazing connecting material and fixedly arranged on a tool base body, a surfacing wear-resistant layer is arranged on the top of the tool, the thickness of the surfacing wear-resistant layer is 5mm, and the edge of the tool is blunt. Finally, the prepared scraper (12 # in the table) is installed on a cutter head B spoke of a shield machine used in a subway shield tunneling project and is compared with the traditional scraper (4 # in the table) used in the project and the scrapers prepared in other embodiments in the practical application performance of the project, and the obtained cutter wear condition statistical table is shown in table 1.
Example 4:
(1) the method is characterized in that tungsten carbide powder with the particle size range of 4 mu m is used as a raw material, a cobalt metal layer is coated on the surface of the tungsten carbide through a chemical plating method surface treatment process, the chemical plating method surface treatment process is a process method for chemically plating cobalt to coat the tungsten carbide based on cobalt salt activation, and the specific implementation steps are the same as those in example 1.
(2) Uniformly mixing a proper amount of the WC-Co composite powder obtained in the step (1) with a certain amount of additives (chromium carbide and tantalum carbide) to obtain WC-Cr3C2-TaC-Co composite powder, wherein chromium carbide0.6% and tantalum carbide 0.4%.
(3) Taking a proper amount of WC-Cr obtained in the step (2)3C2Mixing the-TaC-Co composite powder with a forming agent (paraffin) according to a certain proportion, drying the mixture properly, granulating the mixture by using a screen, then putting the mixture into a graphite die to be compacted and formed (the pressure is 100MPa), and placing a pressure head to finish die assembly. Then placing the die into a sintering cavity and vacuumizing, wherein the vacuum degree is about 1Pa, then starting to heat and sinter, in the sintering process, raising the furnace temperature from room temperature to 200 ℃ at the speed of 3 ℃/min, preserving heat for 0.5h, raising the furnace temperature to 470 ℃ at the speed of 2 ℃/min, preserving heat for 1.5h, raising the furnace temperature to 900 ℃ at the speed of 6 ℃/min, preserving heat for 30min, raising the furnace temperature to 1250 ℃ at the speed of 7 ℃/min, preserving heat for 30min, and finally raising the furnace temperature to 1450 ℃ at the speed of 2.5 ℃/min, preserving heat for 1 h; in the cooling stage, the temperature in the furnace is reduced to room temperature by adopting a furnace cooling mode, and finally WC-Cr is prepared3C2-TaC-Co cemented carbide. And cutting and processing the hard alloy obtained by vacuum sintering into a tool bit.
(4) The WC-Cr prepared in the step (3)3C2the-TaC-Co hard alloy tool bit adopts a medium-frequency and high-frequency induction welding technology, silver-based brazing filler metal is used as a brazing connecting material and fixedly arranged on a tool base body, a surfacing wear-resistant layer is arranged on the top of the tool, the thickness of the surfacing wear-resistant layer is 2mm, and the edge of the tool is blunt. Finally, the prepared scraper (16 # knife in the table) is installed on a cutter head B spoke of a shield machine used in a subway shield tunneling project and is compared with the traditional scraper cutter (4 # knife in the table) used in the project and the scrapers prepared in other embodiments in the practical application performance of the project, and the obtained cutter wear condition statistical table is shown in table 1.
TABLE 1 statistic table for abrasion of B spoke scraper of shield machine cutter head in shield tunneling engineering of subway
TABLE 2 composition and Properties of cemented carbide materials for conventional scraper tools
Table 1 shows a statistical table of wear conditions of cutter blades of a cutter head B spoke scraper of a shield machine used in a shield tunneling project of a subway, in which 14# new type scraper is a scraper prepared by the method of example 1, 7# cutter is a scraper prepared by the method of example 2, 12# cutter is a scraper prepared by the method of example 3, and 16# cutter is a scraper prepared by the method of example 4. It can be seen from table 2 that the wear coefficient of the 14# new blade is significantly lower than that of the original blade and the comparative blade, and the wear coefficient of the 14# new blade is reduced by nearly 50% to the maximum. The abrasion resistance of the novel scraper is superior to that of the original scraper and the comparative cutter, and the feasibility and the superiority of the novel shield cutter material and the preparation process are also proved.
Claims (9)
1. A preparation method of a novel shield tunneling machine scraper is characterized by comprising the following steps:
coating a cobalt metal layer on the surface of tungsten carbide by using tungsten carbide powder as a raw material through a chemical plating surface treatment process to prepare WC-Co composite powder;
adding a certain amount of additive into the WC-Co composite powder obtained in the step (1), and uniformly mixing to obtain WC-Cr3C2-TaC-Co composite powder, wherein the additives are chromium carbide and tantalum carbide;
WC-Cr obtained in step (2)3C2After glue blending, granulation and cold press molding, the-TaC-Co composite powder is subjected to vacuum sintering in a vacuum furnace to prepare WC-Cr3C2-TaC-Co cemented carbide, which is cut to form the design insert;
the WC-Cr prepared in the step (3)3C2The TaC-Co hard alloy tool bit is fixedly arranged on the tool base body.
2. The method according to claim 1, wherein in the step (1), the tungsten carbide has a particle size of 4 to 6 μm.
3. The method according to claim 1, wherein in the step (1), the electroless surface treatment process is a cobalt salt activation-based electroless cobalt-coated tungsten carbide process.
4. The preparation method of the novel shield tunneling machine scraper according to claim 1, wherein in the step (1), the mass of Co in the WC-Co composite powder prepared by the chemical plating surface treatment process accounts for 7wt% -9 wt% of the mass of the composite powder.
5. The method according to claim 1, wherein in the step (2), WC-Cr3C2The mass fraction of chromium carbide in the-TaC-Co composite powder is 0.5-0.7%, and the mass fraction of tantalum carbide is 0.3-0.5%.
6. The preparation method according to claim 1, wherein in the step (3), the vacuum sintering process comprises the following specific steps: weighing a proper amount of WC-Cr3C2Mixing the TaC-Co composite powder with a forming agent in a certain proportion, drying the mixture properly, granulating the mixture by using a screen, and then putting the mixture into a graphite die for compaction forming; and then, placing the graphite mold into a sintering cavity, vacuumizing to about 1-5 Pa, and then, heating and sintering.
7. The preparation method according to claim 6, wherein in the sintering process, the furnace temperature is increased from room temperature to 200 ℃ at a speed of 3 ℃/min, the temperature is kept for 0.5h, then increased to 470 ℃ at a speed of 2 ℃/min, the temperature is kept for 1.5h, then increased to 900 ℃ at a speed of 6 ℃/min, the temperature is kept for 30min, then increased to 1250 ℃ at a speed of 7 ℃/min, the temperature is kept for 30min, and finally increased to 1450 ℃ at a speed of 2.5 ℃/min, the temperature is kept for 1 h; and in the cooling stage, the temperature in the furnace is reduced to room temperature in a furnace cooling mode.
8. The manufacturing method according to claim 1, wherein in the step (4), the hard alloy tool bit is fixedly arranged on the tool shank by using a silver-based brazing filler metal as a brazing connecting material by adopting a medium-high frequency induction welding technology.
9. A shield tunneling machine scraper is characterized by being prepared from the cutter material prepared by the preparation method of any one of claims 1-8.
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| CN109338197A (en) * | 2018-11-06 | 2019-02-15 | 河海大学 | A kind of preparation method of high-compactness WC/Co composite material hard alloy |
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Application publication date: 20200821 |