AU2020101912A4 - Resistance Brazing Method for Shield Machine Cutter - Google Patents
Resistance Brazing Method for Shield Machine Cutter Download PDFInfo
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- AU2020101912A4 AU2020101912A4 AU2020101912A AU2020101912A AU2020101912A4 AU 2020101912 A4 AU2020101912 A4 AU 2020101912A4 AU 2020101912 A AU2020101912 A AU 2020101912A AU 2020101912 A AU2020101912 A AU 2020101912A AU 2020101912 A4 AU2020101912 A4 AU 2020101912A4
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K1/00—Soldering, e.g. brazing, or unsoldering
- B23K1/0004—Resistance soldering
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K1/00—Soldering, e.g. brazing, or unsoldering
- B23K1/0008—Soldering, e.g. brazing, or unsoldering specially adapted for particular articles or work
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550 degrees C
- B23K35/3006—Ag as the principal constituent
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
- B23K35/362—Selection of compositions of fluxes
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Abstract
The present invention relates to the technical field of welding, in particular to a
resistance brazing method for a shield machine cutter. The resistance brazing
5 method for the shield machine cutter of the present invention comprises the steps of:
performing a resistance brazing to an assembly assembled from a cutter body, an
alloy and a silver-based brazing filler metal, wherein an electrode material for the
resistance brazing comprises a graphite felt. According to the present invention,
resistance brazing is applied to the brazing of the shield machine cutter, such that a
.0 reliable and efficient brazing connection between the cutter body and an alloy cutter
bit can be better realised, the brazing strength can be improved, and the service life
of the shield machine cutter can be prolonged.
FIG. 1
.5
1/1
Drawings
alloy
silver-based brazingfiller metal
cutter body
Fig. 1
Description
1/1
Drawings
alloy
silver-based brazingfillermetal
cutter body
Fig. 1
Description
Resistance brazing method for shield machine cutter
This application claims priority from CN application No. 202010030585.7 filed on 13 January 2020, the contents of which are to be taken as incorporated herein by this reference.
Technical Field The present invention relates to the technical field of welding, in particular to a resistance brazing method for a shield machine cutter.
Background Art In the field of underground engineering, tunnel construction with a shield tunnelling machine (shield machine) has the characteristics of a high level of automation, manpower saving, a fast construction speed, one-time tunnel formation, weatherproofing, controllable ground settlement during excavation, reduction of influence on ground buildings and no influence on ground traffic during underwater excavation, etc., and thus the application of shield construction is becoming increasingly wider. Under the condition of a long tunnel line and a deep buried depth, it is more economical and reasonable to use a shield machine for construction. A shield cutterhead and cutter are the parts that directly contact with cuttings and rocks, and are easily damaged. A shield cutter and a substrate are mainly connected by means of brazing, and the brazing quality directly affects the quality of a shield alloy cutter, as well as the cutting effect and tunnelling speed of the shield machine. This requires a high welding quality of the shield alloy cutter.
There are two main brazing processes for traditional alloy cutter a shield machine. In the first brazing process, a medium-frequency induction brazing process is used for direct brazing, wherein a cutter body and a cemented carbide are heated by medium-frequency induction, a sheet silver-based brazing filler metal is brought to the melting temperature by heat conduction and then the brazing is performed. Due to the skin effect of induction heating, the heating is uneven, and the temperature of the cemented carbide and the matrix in the middle area of a cemented carbide cutter for a shield tunnelling heading machine is low. In order to ensure the brazing quality, only long-time heating can be performed, causing part of the cemented carbide is overheated. However, the cemented carbide has a low linear expansion coefficient, a high hardness, a high brittleness and a small thermal conductivity, and thus a long-time and high-temperature heating can easily cause the breaking and cracking of the cemented carbide ball teeth and the shedding of the cemented carbide, causing the damage of the cutter and thus an impossibility of tunnelling. In the second brazing process, a composite process of medium frequency brazing and flame brazing is used, wherein the cutter body and cemented carbide are heated by medium frequency induction. However, due to the skin effect of induction heating, the heating is uneven, and the temperature of the cemented carbide and the matrix in the middle area of the cemented carbide cutter for the shield tunnelling heading machine is low, and the flame brazing is mainly used to heat the area with a low temperature. This brazing process is complex and difficult to realise automatic production.
The difficulty of a shield cutter brazing project lies in realizing a reliable and efficient brazing connection between a steel matrix and a cemented carbide cutter bit. At present, the induction heating brazing is widely used in the industry. Due to the skin effect of induction heating, the temperature difference between the inside and outside of a workpiece is large, which brings two fatal problems: 1) due to the inconsistent linear expansion in the heating process, the cutter has a larger internal stress; and 2) heating and heat transfer for a long time are necessary, which leads to external overheating and brazing filler metal turbulence. On the other hand, they lead to severe cutter oxidation.
In view of the above, the present invention has been proposed.
Summary The present invention relates to a resistance brazing method for a shield machine cutter, comprising the steps of: performing a resistance brazing on an assembly assembled from a cutter body, an alloy and a silver-based brazing filler metal, wherein an electrode material for the resistance brazing comprises a graphite felt.
The present invention departs from the traditional method for brazing of a carbide cutter of a shield machine wherein a medium-frequency brazing apparatus is used and the cutter body and cemented carbide are heated in the air as well as the sheet silver-based brazing filler metal is heated to a melting temperature for direct brazing. In addition, the present invention intends to solve the problems that some cemented carbide in the welding seam after brazing is overheated and while being heated at a high temperature for a long time, the cemented carbide ball teeth are prone to break, crack, and be oxidised to include slag, due to a low coefficient of linear expansion, high hardness, high brittleness and low thermal conductivity of the cemented carbide, causing the cemented carbide shedding. Furthermore, the present method can improve the strength and efficiency of brazing.
Compared with the prior art, the beneficial effects of the present invention are: according to the present invention, resistance brazing is applied to shield machine brazing, and a graphite felt is used as an electrode, such that the shield machine cutter can be better brazed, and the welding strength of the cutter of and the efficiency of the shield machine can be further improved.
Brief Description of the Drawings In order to illustrate the technical solutions in the particular embodiments of the present invention or in the prior art more clearly, the accompanying drawings to be used in the description of the particular embodiments or the prior art will be briefly introduced below; obviously, the accompanying drawings in the following description show some of the embodiments of the present invention, and those of ordinary skill in the art may still derive other drawings from these accompanying drawings without creative effort. Fig. 1 is a schematic diagram of the assembly position relationship among the cutter body, silver-based brazing filler metal and alloy of the present invention.
Detailed Description of Embodiments The embodiments of the present invention will be described in detail with reference to embodiments below; however, it would be understood by those skilled in the art that the embodiments below are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. If the specific conditions are not indicated in the embodiments, the conventional conditions or the conditions suggested by the manufacturer shall be followed. Any reagents or instruments used, unless the manufacture stated, are conventional products that can be obtained by market purchase.
The present invention relates to a resistance brazing method for a shield machine cutter, comprising the steps of: performing a resistance brazing to an assembly assembled from a cutter body, an alloy and a silver-based brazing filler metal, wherein an electrode material for the resistance brazing comprises a graphite felt.
The basic principle of resistance brazing relates to a high current, a low voltage and an electrode with a high resistance circuit, that is, a high current generates high resistance heat through a carbon electrode, which is directly conducted to a brazing joint, such that the brazing filler metal in the joint is melted after reaching the melting temperature. During performing the brazing, a certain pressure should be applied to the brazing site, and under the action of the pressure, a firm brazing joint is formed after solidification. This method has the advantages of rapid heating, a high productivity, a small heat influence on the surrounding due to concentrated heating, a simple process, good labour conditions and an easy automation of a welding process, etc.
The resistance brazing apparatus of the present invention is a traditional resistance brazing apparatus which is provided with a sealed shell, with one end being provided with an air inlet channel, and the other end being provided with an air outlet channel and an oxygen partial pressure test channel. The upper and lower electrodes of the resistance brazing apparatus are graphite felts.
The shield cutter has a curved face or a special-shaped surface, the graphite electrode is in a hard contact with the shield cutter during resistance brazing, and cracks will occur on the graphite electrode under the action of a pressure; the graphite felt used in the present invention is softer, and has the characteristics of a good conductivity and plasticity, a high temperature resistance (resistance to temperatures above 700°C), etc.
The assembly method of the assembly in the present invention is specifically as follows: arranging a silver-based brazing filler metal above a cutter body, and arranging an alloy above the silver-based brazing filler metal. The schematic diagram of their positional relationship is shown in Fig. 1.
Preferably, during the resistance brazing process, an oxygen content is 0.01-20 ppm, and a pressure is 5-40 kN.
According to the present invention, the air inlet channel is opened at the beginning of brazing, the oxygen content of an oxygen partial pressure meter is controlled to be 0.01-20 ppm, and then a power supply is turned on for pressurization with a pressure of 5-40 kN. If the oxygen partial pressure is too high, an oxide film that is not easy to move will be produced on the surface of the base metal, which will prevent the brazing filler metal from wetting the base metal. Therefore, by controlling the oxygen content of the oxygen partial pressure meter and the pressure, the resistance brazing can be better completed and the welding strength can be improved.
Preferably, the alloy is a cemented carbide and/or a PDC composite sheet (polycrystalline diamond compact, PDC for short).
The alloy of the invention can be a traditional cemented carbide or a PDC composite sheet. The PDC composite sheet is preferred. The PDC composite sheet is a new functional material, which is made by sintering a diamond micro-powder and a cemented carbide substrate under ultra-high pressure and high temperature conditions. The PDC composite sheet not only has the high hardness, high wear resistance and thermal conductivity of diamond, but also has the strength and impact toughness of the cemented carbide, and thus is an ideal material for manufacturing cutters, drilling bits and other wear-resistant tools.
Preferably, the silver-based brazing filler metal is a sheet silver-based brazing filler metal; and preferably, the sheet silver-based brazing filler metal comprises BAg50Cu2OZn28Ni2 and/orBAg49Cul6Zn23Ni4.5Mn7.5.
The silver-based brazing filler metal used in the present invention has excellent technological properties, a low melting point, a good wettability and a gap-filling performance, and has excellent strength, plasticity, conductivity and corrosion resistance.
Preferably, the silver-based brazing filler metal is a composite brazing filler metal sheet; and preferably, the composite brazing filler metal sheet comprises 50%-60% of an intermediate layer and 20%-25% of each of alloy layers on either side thereof by mass percentage; wherein the intermediate layer of the composite brazing filler metal sheet is an ZnCuAgMn alloy, and the alloy layers on either side thereof are an AgCuLi alloy, respectively; preferably, the mass percentages of Zn, Cu, Ag and Mn in the ZnCuAgMn alloy are 50%-60%,l0%-15%,15%-25% and 0.01%-15%, respectively; more preferably, the ZnCuAgMn alloy is Zn57Cul4Agl5Mnl4; preferably, the mass percentages of Ag, Cu and Li in the AgCuLi alloy are 65.7%-75%,24.99%-34% and 0.01%-0.3%, respectively; preferably, the cutter body is sprayed with a layer of nickel or a nickel-cobalt alloy with a thickness of 0.001-0.1 mm at the location where the alloy is arranged. More preferably, the AgCuLi alloy is Ag72Cu27.8LiO.2.
During performing the brazing, AgCuLi on one side can form a good metallurgical bond with the cutter body, and AgCuLi on the other side can also be better bonded with the alloy (cutter bit).
In one embodiment, the intermediate layer accounts for 50%-60% by mass percentage of the composite brazing filler metal sheet, such as 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58% or 59%.
In one embodiment, each of the alloy layers on either side of the intermediate layer accounts for 20%-25% by mass percentage of the composite brazing filler metal sheet, such as 21%, 22%, 23% or 24%.
In one embodiment, before assembling the cutter body, the alloy and the silver-based brazing filler metal, a layer of nickel or a nickel-cobalt (NiCo10) alloy with a thickness of 0.001-0.1mm is sprayed on the surface (where the alloy sheet is arranged) of the cutter body.
In one embodiment, the alloy is a PDC composite sheet and the brazing filler metal is a composite brazing filler metal sheet. If the cemented carbide is directly replaced with the PDC composite sheet, the wear resistance will be greatly improved, but the diamond begins to suffer different degrees of damage at a temperature above 700°C, as shown by: surface graphitization, and appearance of cracks or fragmentations etc., in the particles, which leads to reductions in performances such as cuttings, impact and wear resistance. Due to the strength requirement, the commonly used brazing filler metals for the shield cutter are BAg50Cu2OZn28Ni2 (a melting temperature of 660°C-705°C) and BAg49Cul6Zn23Ni4.5Mn7.5 (a melting temperature of 680°C-705°C), and the brazing temperature is about 750°C, causing the graphitization of the diamond in the PDC composite sheet. In the present invention , the melting point of the inner layer of the composite brazing filler metal sheet used is slightly lower than that of the outer layer, such that the strength of the welded point can be further improved. The alloy composition of a brazing seam is BAg50Cu2OZn28Ni2LiCo and BAg49Cul6Zn23Ni4.5Mn7.5LiCo.
Preferably, the surfaces of the cutter body and the alloy of the assembly body are coated with a flux paste; preferably, the flux paste comprises a QJ102 flux paste; preferably, the flux paste comprises the following components in parts by weight: 75-85 parts of a QJ102 flux paste, 1-4 parts of a boron powder and 10-15 parts of a wetting agent, more preferably, the wetting agent comprises a colloid and/or water.
In one embodiment, the QJ102 flux paste is 75-85 parts, such as 76 parts, 77 parts, 78 parts, 79 parts, 80 parts, 81 parts, 82 parts, 83 parts or 84 parts.
In one embodiment, the boron powder is 1-4 parts, such as 1.5 parts, 2 parts, 2.5 parts, 3 parts or 3.5 parts.
In one embodiment, the wetting agent is 10-15 parts, such as 11 parts, 12 parts, 13 parts or 14 parts.
After the assembly of the present invention is formed, a small amount of the flux paste is applied to prevent oxidation in a high temperature environment and reduce the oxidation of the welding seam. A flow blocking agent is applied on the surface of the cutter body below the cemented carbide, wherein the flow blocking agent comprises an alumina paste, an alumina emulsion, a graphite paste or a graphite emulsion.
The QJ102 flux paste comprises the following components in percentage by mass: 42% of potassium fluoride, 23% of potassium fluoborate and 35% of boron anhydride.
Preferably, in the assembly, the surface of the cutter body outside the alloy is coated with a brazing coating; preferably, the brazing coating is prepared from the following components in parts by weight: 5-35 parts of a diamond micro-powder, 5-15 parts of the QJ102 flux paste, 20-35 parts of a silver-based brazing filler metal powder, 25-40 parts of carbide particles and 10-35 parts of an adhesive; in order to improve the welding quality of the shield machine cutter, it is necessary to brazing a wear-resistant coating after welding. The method of brazing first and then surfacing the wear-resistant layer has a complicated process, a high heating temperature and a large thermal damage, which makes it difficult to realise automatic production. According to the present invention, the brazing process is carried out at the same time of resistance brazing. Thereby a shield machine cutter with better performance is obtained.
In one embodiment, the diamond micro-powder is 5-35 parts, such as 10 parts, 15 parts, 20 parts, 25 parts or 30 parts.
In one embodiment, the QJ102 flux paste is 5-15 parts, such as 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts or 14 parts.
In one embodiment, the silver-based brazing filler metal powder is 20-35 parts, such as 25 parts or 30 parts.
In one embodiment, the carbide particle is 25-40 parts, such as 30 parts or 35 parts.
In one embodiment, the adhesive is 10-35 parts, such as 15 parts, 20 parts, 25 parts or 30 parts.
According to the present invention, the brazed coating obtained by combining various components has excellent wear resistance and strength.
Preferably, the brazed coating is prepared from the following components in parts by weight: 10-20 parts of the diamond micro-powder, 7-12 parts of the QJ102 flux paste, 22-30 parts of the silver-based brazing filler metal powder, 28-35 parts of the carbide particle and 15-30 parts of the adhesive.
The wear resistance and strength of the coating can be further improved by further optimizing the raw material ratio of the coating.
Preferably, the silver-based brazing filler metal powder comprises BAg50Cu2OZn28Ni2and/orBAg49Cul6Zn23Ni4.5Mn7.5; preferably, the carbide includes titanium carbide and/or chromium carbide.
Preferably, the particle size of the diamond micro-powder is 140-325 meshes.
In one embodiment, the particle size range of the diamond micro-powder is 140-325 meshes, such as 170 meshes, 200 meshes, 230 meshes, 250 meshes, 270 meshes or 300 meshes.
Preferably, the particle size of the diamond micro-powder is 200-300 meshes.
Preferably, the particle size of the carbide particle is 30-100 meshes.
In one embodiment, the particle size of the carbide particle is 30-100 meshes, such as 40 meshes, 50 meshes, 60 meshes, 70 meshes or 80 meshes.
Preferably, the particle size of the carbide particle is 40-60 meshes; Preferably, the particle size of the silver-based brazing filler metal powder is 180-300 meshes.
In one embodiment, the particle size range of the silver-based brazing filler metal powder is 180-300 meshes, such as 170 meshes, 200 meshes, 230 meshes, 250 meshes, or 270 meshes.
Preferably, the particle size of the silver-based brazing filler metal powder is 200-250 meshes.
According to the present invention, the traditional cemented carbide is replaced with the PDC composite sheet, and the traditional surfacing tungsten carbide particle is replaced with the brazed diamond micro-powder, such that the welding temperature is reduced, the thermal damage is small, the brazing and the wear-resistant layer welding are integrated, and the efficiency and the product quality are improved.
Preferably, the resistance brazing process includes a process of preheating and heating; preferably, the assembly is preheated to 490°C-520°C with the temperature maintained for 1-60 s, and heated to 725°C-800°C with the temperature maintained for 30-120 s; preferably, after heating, the assembly is cooled to a temperature of 180°C-250 0 C.
In one embodiment, the assembly is cooled to a temperature of 180°C-250°C, such as 190°C, 200°C, 210°C, 220°C, 230°C or 240°C.
Preferably, the heating process is performed by medium frequency induction heating.
In order to achieve the comparison purpose with the induction welding, the side of the shield cutter is drilled with a hole having a depth of 90 mm, and in the case that a real-time temperature is monitored with a thermocouple during the heating process, the following operations are performed: a weldment is preheated with a resistance welder in advance, so that the temperature of the weldment can reach 490°C-520°C and then the temperature is maintained for 1-60 s; and the weldment is heated again, and the temperature and temperature rise are recorded, and the temperature is raised to 725°C-800°C and maintained for 30-120 s until the brazing filler metal is melted. Resistance heating or medium frequency induction heating can be used in the heating process.
In one embodiment, the brazing of the shield cutter comprises two stages, wherein in the first stage, a resistance heating is performed for overall preheating, and in the second stage, a medium frequency induction heating is performed mainly for heating the weld area to improve the efficiency and quality of brazing, and reduce the energy consumption.
The present invention will be further explained with reference to specific examples below.
Example 1 A resistance brazing method for a shield machine cutter, comprising the steps of:
(a) performing a sand blasting treatment to a cutter body, a cemented carbide and a sheet silver-based brazing filler metal BAg50Cu2Zn28Ni2; (b) assembling the cutter body, the cemented carbide and the sheet silver-based brazing filler metal into an assembly, coating a surface of the cemented carbide with a QJ102 flux paste, and coating a surface of the cutter body below the cemented carbide with an alumina paste; (c) performing a resistance brazing to the assembly, wherein the resistance brazing apparatus of the present invention is provided with a sealed shell at the outside, with one end being provided with an air inlet channel for introducing nitrogen or argon for protection, and the other end being provided with an air outlet channel and an oxygen partial pressure test channel (connected with an oxygen partial pressure tester). The upper and lower electrodes of the resistance brazing apparatus are graphite felts, and the power of the resistance brazing apparatus is 80-200 kW. The assembly is placed between the upper and lower electrodes of the resistance brazing apparatus, and the air inlet channel is opened such that the oxygen content of the oxygen partial pressure meter reaches 20 ppm; a power supply is then turned on for pressurization with a pressure of 40 kN; the side of the shield cutting tool is drilled with a hole depth of 90 mm; and a real-time temperature is monitored with a thermocouple during the heating process, wherein a weldment is preheated with a resistance welder in advance, such that the temperature of the weldment can reach 500°C and then the temperature is maintained for 30 s, the weldment is heated again, and the temperature and temperature rise are recorded, and the temperature is raised to 725°C and maintained for 1 min until the brazing filler metal is melted; and (d) cooling the assembly to 180°C in a sealing apparatus and then taking out the assembly.
Example 2 A resistance brazing method for a shield machine cutter, comprising the steps of:
(a) performing a sand blasting treatment to a cutter body, a cemented carbide and a sheet silver-based brazing filler metal BAg49Cul6Zn23Ni4.5Mn7.5; (b) assembling the cutter body, the cemented carbide and the sheet silver-based brazing filler metal into an assembly, with the surface of the cemented carbide being coated with a QJ102 flux paste, wherein a small amount of the QJ102 flux paste is applied after the assembly is formed; and the surface of the cutter body below the cemented carbide is coated with an alumina emulsion; (c) performing a resistance brazing to the assembly, wherein the resistance brazing/induction brazing composite apparatus of the present invention is a resistance brazing apparatus which is provided with a sealed shell at the outside, with one end being provided with an air inlet channel for introducing nitrogen or argon for protection, and the other end being provided with an air outlet channel and an oxygen partial pressure test channel (connected with an oxygen partial pressure tester). The upper and lower electrodes of the resistance brazing apparatus are graphite felts with a medium frequency induction heating coil being arranged therebetween. The power of the resistance brazing apparatus is 200 kW. The assembly is placed between the upper and lower electrodes of the resistance brazing apparatus, and the air inlet channel is opened such that the oxygen content of the oxygen partial pressure meter reaches 10 ppm; a power supply is then turned on for pressurization with a pressure of 5kN; in order to achieve the comparison purpose with the induction welding, the side of the shield cutting tool is drilled with a hole depth of 90 mm, the real-time temperature is monitored with a thermocouple during the heating process, a weldment is preheated with a resistance welder in advance, such that the temperature of the weldment can reach 520°C and then the temperature is maintained for 20 s; the medium frequency induction heating is turned on, and the temperature and temperature rise are recorded, the temperature is then raised to 800°C and maintained for 30 s until the brazing filler metal is melted; and (d) cooling the assembly to 250°C in a sealing apparatus and then taking out the assembly.
Example 3 A resistance brazing method for a shield machine cutter, comprising the steps of: (a) performing a sand blasting treatment to a cutter body, a PDC composite sheet and a composite brazing filler metal sheet BAg72Cu27.8LiO.2/ Zn57Cul4Ag15Mn14/BAg72Cu27.8LiO.2, wherein the composite brazing filler metal sheet comprises 50% of an intermediate layer Zn57Cul4Agl5Mnl4 and 25% of each of layers Ag72Cu27.8Li.2 on either side thereof by mass percentage; (b) applying a nickel-cobalt alloy layer (NiCo10) with a thickness of 0.01 mm onto the PDC composite sheet and a groove of the cutter body (where the PDC composite sheet is placed); (c) assembling the cutter body, the PDC composite sheet and the sheet silver-based brazing filler metal into an assembly, which is then coated with a small amount of the flux paste and subjected to a resistance brazing, wherein the resistance brazing apparatus is the same as Example 1, and the flux paste comprises the following components in parts by weight: 75-85 parts of the QJ102 flux paste, 1-4 parts of the boron powder and 10-15 parts of water, and wherein the power of the resistance brazing apparatus is 80-200 kW, the side of the shield cutter is drilled with a hole having a depth of 90 mm, the real-time temperature is monitored with a thermocouple in the heating process, a weldment is preheated with a resistance welder in advance, such that the temperature of the weldment can reach 510°C and then the temperature is maintained for 40 s, the weldment is heated again, and the temperature and the temperature rise are recorded, and the temperature is raised to 670°C and maintained for 2 mins until the brazing filler metal is melted and fully dispersed for reaction; and (d) cooling the assembly to 210°C in a sealing apparatus and then taking out the assembly.
Example 4
A resistance brazing method for a shield machine cutter differs from that in Example 3 in that: the composite brazing filler metal sheet comprises 60% of the intermediate layer Zn57Cul4Agl5Mnl4 and 20% of each of layers Ag72Cu27.8Li.2 on either side thereof by mass percentage. The other operations are the same as in Example 3.
Example 5 A resistance brazing method for a shield machine cutter in this example differs from that in Example 3 in that: the composite brazing filler metal sheet comprises 56% of the intermediate layer Zn57Cul4Agl5Mnl4 and 22% of each of layers Ag72Cu27.8Li.2 on either side thereof by mass percentage. Other operations are the same as in Example 3.
Example 6 A resistance brazing method for a shield machine cutter, comprising the steps of: (a) performing a sand blasting treatment to a cutter body, a PDC composite sheet and a sheet silver-based brazing filler metal BAg50Cu2Zn28Ni2; (b) assembling the cutter body, the PDC composite sheet and the sheet silver-based brazing filler metal BAg50Cu2OZn28Ni2 into an assembly; applying a small amount of the flux paste after the assembly is formed; and applying a brazed coating onto the PDC composite sheet and the surface of the cutter body below the PDC composite sheet, wherein the brazed coating is prepared from the following components in parts by weight: 5 parts of a diamond micro-powder, 15 parts of a QJ102 flux paste, 20 parts of a silver-based brazing filler metal powder, 40 parts of carbide particles and 35 parts of an adhesive, wherein the silver-based brazing filler metal powder comprises BAg50Cu2Zn28Ni2, and the carbide is titanium carbide. The particle size of the diamond micro-powder is 150-200 meshes; the particle size of the carbide particle is 50-60 meshes; and the particle size of the silver-based brazing filler metal powder is 200-300 meshes;
(c) performing a brazing to the assembly with the same resistance brazing apparatus as in Example 1, wherein the power of the resistance brazing apparatus is 150 kW, the assembly is placed between the upper and lower electrodes of the resistance brazing apparatus, and the air inlet channel is opened such that the oxygen content of the oxygen partial pressure meter reaches 0.01 ppm; a power supply is then turned on for pressurization with a pressure of 30kN; the side of the shield cutter is drilled with a hole depth of 90 mm; the real-time temperature is monitored with a thermocouple during the heating process, a weldment is preheated with a resistance welder in advance, such that the temperature of the weldment can reach 500°C and then the temperature is maintained for 30 s, the weldment is heated again, and the temperature and temperature rise are recorded, and the temperature is raised to 780°C and maintained for 2 mins until the brazing filler metal is melted; and (d) cooling the assembly to 210°C in a sealing apparatus and then taking out the assembly.
Example 7 A resistance brazing method for a shield machine cutter in this example differs from that in Example 6 in that: the brazed coating is prepared from the following components in parts by weight: 35 parts of the diamond micro-powder, 5 parts of the QJ102 flux paste, 35 parts of the silver-based brazing filler metal powder, 25 parts of the carbide particle and 10 parts of the adhesive; the silver-based brazing filler metal powder comprises BAg49Cul6Zn23Ni4.5Mn7.5, and the carbide is chromium carbide; and the particle size of the diamond micro-powder is 300 meshes, the particle size of the carbide particles is 30-40 meshes, and the particle size of the silver-based brazing filler metal powder is 180-200 meshes. Other operations are the same as in Example 6.
According to Examples 1-7 of the present invention, the resistance brazing is used for performing the brazing to the shield machine cutter, and a graphite felt is used as an electrode, such that the shield machine cutter can be better brazed, and the welding strength and service life of the shield machine cutter can be further improved.
In Example 1, the cutter body, the cemented carbide and the sheet silver-based brazing filler metal BAg50Cu2OZn28Ni2 are assembled, and the brazing strength can be better improved by resistance brazing.
In Example 2, the cutter body, the cemented carbide and the sheet silver-based brazing filler metal BAg49Cul6Zn23Ni4.5Mn7.5 are assembled, and medium frequency induction brazing is incorporated in the resistance brazing process, i.e., resistance heating is used in the first stage for overall preheating, and the medium frequency induction heating is used in the second stage, which focuses on heating the weld area to improve the efficiency and quality of brazing, and reduce the energy consumption.
In Examples 3-5, the cutter body, the PDC composite sheet and the composite brazing filler metal sheet are assembled, wherein the composite brazing filler metal sheet is composed of three layers of alloys, and the melting point of the inner layer is slightly lower than that of the outer layer; by means of specific resistance brazing operation, the inner and outer layers of alloys are fused and diffused to the base metal in the brazing process, thus realizing in-situ metallurgical synthesis of new alloys and obtaining high-strength brazing seams.
In Examples 6 and 7, the cutter body, the PDC composite sheet and the sheet silver-based brazing filler metal are assembled and resistance brazed, and brazed coating is carried out at the same time; the brazing strength and service life of the shield cutter are further improved by combining the specific brazed coating composition with the resistance brazing process.
It should be finally noted that, the above embodiments are merely used for illustrating, rather than limiting, the technical solutions of the present invention.
Although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the field that the technical solutions specified in the foregoing embodiments could still be modified, or some or all of the technical features thereof may be equivalently s replaced; and the modifications or replacements do not make the essence of corresponding technical solutions depart from the scope of the technical solution of the embodiments of the present invention.
Claims (5)
1. A resistance brazing method for a shield machine cutter, comprising the steps of: performing a resistance brazing to an assembly assembled from a cutter body, an alloy and a silver-based brazing filler metal, wherein an electrode material for the resistance brazing comprises a graphite felt, wherein during the resistance brazing process, an oxygen content is 0.01-20 ppm and a pressure is 5-40 kN, and wherein the alloy is a cemented carbide and/or a PDC composite sheet.
2. The resistance brazing method for the shield machine cutter according to claim 1, wherein the silver-based brazing filler metal is a sheet silver-based brazing filler metal, and wherein the sheet silver-based brazing filler metal includes BAg50Cu2OZn28Ni2and/orBAg49Cul6Zn23Ni4.5Mn7.5.
3. The resistance brazing method for the shield machine cutter according to claim 1 or 2, wherein the silver-based brazing filler metal is a composite brazing filler metal sheet, the composite brazing filler metal sheet comprising 50%-60% of an intermediate layer and 20%-25% of each of alloy layers on either side thereof by mass percentage, the intermediate layer of the composite brazing filler metal sheet being formed of an ZnCuAgMn alloy and the alloy layers on either side being formed of an AgCuLi alloy, wherein the mass percentages of Zn, Cu, Ag and Mn in the ZnCuAgMn alloy are 50%-60%,l0%-15%,15%-25% and 0.01%-15%, respectively, and wherein the mass percentages of Ag, Cu and Li in the AgCuLi alloy are 65.7%-75%,24.99%-34% and 0.01%-0.3%, respectively.
4. The resistance brazing method for the shield machine cutter according to any one of claims 1-3, further comprising coating a flux paste onto surfaces of the cutter body and alloy of the assembly, wherein the flux paste comprises the following components in parts by weight: 75-85 parts of a QJ102 flux paste, 1-4 parts of a boron powder and 10-15 parts of a wetting agent, the wetting agent comprising a colloid and/or water.
5. The resistance brazing method for the shield machine cutter according to claim 4, further comprising coating a brazing coating onto the surface of the cutter body outside the alloy in the assembly, wherein the brazing coating is prepared from the following components in parts by weight: 5-35 parts of a diamond micro-powder, 5-15 parts of a QJ102 flux paste, 20-35 parts of a silver-based brazing filler metal powder, 25-40 parts of carbide particles and 10-35 parts of an adhesive, wherein the silver-based brazing filler metal powder includes BAg50Cu2OZn28Ni2 and/or BAg49Cul6Zn23Ni4.5Mn7.5, wherein the carbide includes titanium carbide and/or chromium carbide, and wherein a particle size of the diamond micro-powder is 140-325 meshes.
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| CN202010030585.7A CN111037021B (en) | 2020-01-13 | 2020-01-13 | Resistance brazing method for shield machine cutter |
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| CN113004865A (en) * | 2021-03-05 | 2021-06-22 | 河南晶锐新材料股份有限公司 | Polycrystalline diamond compact vacuum packaging flow choking agent and flow choking structure |
| CN113579386B (en) * | 2021-08-12 | 2023-02-21 | 郑州机械研究所有限公司 | Brazing flux-free brazing method for hard alloy cutter |
| CN114589468A (en) * | 2022-04-02 | 2022-06-07 | 合肥聚能电物理高技术开发有限公司 | Repair process and joint of water-cooled cable |
| CN114850646B (en) * | 2022-05-24 | 2023-10-03 | 湖南威盾新材料技术有限责任公司 | Resistance welding method between hard alloy sheet and metal matrix |
| CN116117258A (en) * | 2023-02-07 | 2023-05-16 | 哈尔滨工业大学 | Rapid resistance brazing method with carbon material intermediate layer as heat source |
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| JP5837779B2 (en) * | 2010-09-07 | 2015-12-24 | 日本特殊陶業株式会社 | Tool assembly, cutting tool using the same, and method for manufacturing the tool assembly |
| CN103008993B (en) * | 2012-11-29 | 2015-06-24 | 洛阳九久技术开发有限公司 | Manufacturing method of shield machine scraper |
| CN104259610B (en) * | 2014-08-27 | 2016-05-11 | 郑州机械研究所 | A kind of resistance brazing method and device thereof that adopts graphite electrode |
| CN104646852B (en) * | 2014-12-31 | 2017-06-23 | 苏州铜宝锐新材料有限公司 | Pricker applies cream and its application |
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| CN109465561B (en) * | 2018-12-13 | 2021-04-02 | 郑州机械研究所有限公司 | Gradient sandwich brazing filler metal for hard alloy brazing |
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