Wheel shaping block for locomotive and preparation method of wheel shaping block

Abstract

The invention relates to the field of railway vehicle brake materials, in particular to a wheel shaping block for a locomotive and a preparation method of the wheel shaping block. The wheel shaping block for the locomotive comprises an upper-layer shaping part and a lower-layer supporting seat which are integrally connected, the shaping part comprises the following raw materials in parts by weight: 12-14 parts of phenolic resin, 2-4 parts of graphite, 10-12 parts of bauxite, 8-9 parts of silicon carbide, 5-8 parts of brass powder, 36-40 parts of iron powder, 10-16 parts of copper fibers, 5-7 parts of steel fibers, 2-3 parts of precipitated barium sulphate, 20-25 parts of nano SiO2 modified PEEK and 10-15 parts of graphene modified PPS; the supporting seat comprises the following raw materials in parts by weight: 80-85 parts of iron powder, 6-8 parts of copper powder, 2-3 parts of molybdenum powder, 4-6 parts of nickel powder and 1-2 parts of zinc stearate. The modification part in the modification block has a lower friction coefficient and higher impact strength and wear resistance, and is long in service life and high in safety.

Description

Technical Field

[0001] The invention relates to the field of rail vehicle brake materials, in particular to a locomotive wheel shaping block and a preparation method thereof. Background Art

[0002] Under locomotive wheel operation conditions, high-order wheel polygon wear can cause strong vibrations between the wheel and rail, impacting operational economy and safety. Therefore, locomotive wheels are typically equipped with a shaping part. During braking, the shaping part presses against the tread to clean it, ensuring that the wheel tread remains in good working condition.

[0003] To reduce wear caused by wheel flange contact with curved rails, lubricant is currently applied to the wheel tread via a lubricator. This can easily lead to wheel slippage and even derailment. Furthermore, the lubricant in the lubricator consumes quickly and has low impact resistance. Summary of the Invention

[0004] The purpose of the present invention is to address the problems existing in the background technology and propose a locomotive wheel shaping block and a preparation method thereof. The prepared shaping block has a low friction coefficient, high impact strength and wear resistance, a long service life and high safety.

[0005] In one aspect, the present invention provides a locomotive wheel trimming block comprising an integrally connected upper trimming portion and a lower support base. The trimming portion comprises the following raw materials, in parts by weight: 12-14 parts phenolic resin, 2-4 parts graphite, 10-12 parts bauxite, 8-9 parts silicon carbide, 5-8 parts brass powder, 36-40 parts iron powder, 10-16 parts copper fiber, 5-7 parts steel fiber, 2-3 parts precipitated barium sulfate, 20-25 parts nano-SiO2-modified PEEK, and 10-15 parts graphene-modified PPS. The support base comprises the following raw materials, in parts by weight: 80-85 parts iron powder, 6-8 parts copper powder, 2-3 parts molybdenum powder, 4-6 parts nickel powder, and 1-2 parts zinc stearate.

[0006] Preferably, when preparing nano-SiO2 modified PEEK, PEEK particles and modified SiO2 are premixed in a mixer for 10-12 minutes; the mixture is extruded through a twin-screw extruder, the feed section temperature of the twin-screw extruder is 320°C, the melting section temperature is 370°C, the homogenization section temperature is 380°C, and the head temperature is 350°C; the extruded strips are water-cooled and then pelletized and dried at 120°C for 4 hours.

[0007] Preferably, when preparing graphene-modified PPS, the PPS particles and reduced graphene oxide are dried at 130°C for 3 hours, respectively, and premixed in a mixer for 10 minutes, and the mixture is extruded through a twin-screw extruder, the feeding section temperature of the twin-screw extruder is 280°C, the melting section temperature is 300°C, the homogenizing section temperature is 305°C, and the head temperature is 290°C; the extruded strips are water-cooled and then pelletized and dried at 120°C for 4 hours.

[0008] Preferably, when preparing graphene-modified PPS, the graphene oxide is reduced by a side feeding method.

[0009] Preferably, when the nano-SiO2 modified PEEK and graphene modified PPS are extruded and granulated, vacuum devolatilization treatment is performed to remove volatiles.

[0010] In another aspect, the present invention provides a method for preparing the locomotive wheel shaping block, comprising the following steps:

[0011] S1, preparing a trimming blank, including the following steps S11-S13:

[0012] S11, raw material pretreatment:

[0013] The copper fiber and steel fiber were soaked in 5% silane coupling agent ethanol solution for 30 minutes and dried at 90°C. The nano-SiO2 modified PEEK was dried in an oven at 180°C for 3 hours. The graphene modified PPS was milled at low temperature to produce a powder with a particle size of less than 50 μm.

[0014] S12, Mixed:

[0015] Dry mixing stage: first add phenolic resin, graphite, bauxite, silicon carbide and precipitated barium sulfate into a mixer at a speed of 500 rpm and mix for 10-12 minutes; then add brass powder, iron powder, copper fiber and steel fiber and mix for 4-6 minutes;

[0016] Wet mixing stage: spray anhydrous ethanol and continue mixing for 15-17 minutes until the slurry is uniform, then add nano-SiO2 modified PEEK and graphene modified PPS, and mix at 200 rpm for 10-12 minutes to prepare a mixture;

[0017] S13, hot pressing:

[0018] The mold is preset to 160-170°C, the mixture is loaded, and pressurized in stages. The first stage is cured at 10MPa and 160°C for 30 minutes, which is pre-curing; the second stage is cured at 30MPa and 180°C for 60 minutes, which is full curing. After full curing, demoulding is performed to obtain the blank of the trimming part;

[0019] S2. Using powder metallurgy technology to prepare a support base blank, including the following steps S21-S24:

[0020] S21. Powder drying:

[0021] Iron powder, copper powder, molybdenum powder and nickel powder were dried under vacuum at 120°C for 2 hours;

[0022] S22, mixing:

[0023] Add the dried iron powder, copper powder, molybdenum powder and nickel powder to a mixer, mix at a speed of 30-50 rpm for 2-3 hours, then add zinc stearate and mix to obtain a mixture;

[0024] S23, compression molding:

[0025] The mixed material is pressed into shape using a hydraulic press at a pressure of 600-700 MPa and a holding time of 50-60 seconds to obtain a green material;

[0026] S24, sintering:

[0027] The green material is sintered in a vacuum sintering furnace in four stages: degreasing stage: 300°C, 1 hour; pre-sintering: 800°C, 1 hour; high temperature sintering: 1150°C, 2 hours; slow cooling: the vacuum sintering furnace is cooled to below 200°C and then taken out of the furnace to obtain the support base blank;

[0028] S3. Overall hot pressing:

[0029] Place the trimming part blank on the support base blank, and use a hot press to press it at 1000-2000 MPa. Heat the entire blank to 600-850°C and keep it warm for 30-35 minutes to obtain a trimming block semi-finished product.

[0030] S4. Overall curing:

[0031] The semi-finished product of the trimming block is placed in a curing oven and cured at 140-160° C. for 8-9 hours to obtain a finished product of the trimming block.

[0032] Preferably, the shaping portion blank preparation step further includes S14, post-processing: using a fiber laser to process a micron-scale pit array on the working surface, with the pit diameter being 100-110 μm, the depth being 40-50 μm, and the spacing being 200-220 μm.

[0033] Compared with existing technologies, the present invention offers the following beneficial technical advantages: the trimming portion of the trimming block exhibits low wear and friction coefficient. Nano-SiO2-modified PEEK enhances wear resistance and reduces wear rate, while graphene-modified PPS provides toughness and improved impact strength. Furthermore, graphene-modified PPS enhances the thermal conductivity of the trimming block, enabling efficient heat dissipation and reducing heat accumulation, resulting in a long service life and enhanced safety. The trimming block effectively reduces the out-of-roundness amplitude and surface roughness of wheels (such as those used in electric locomotives), resulting in excellent trimming results. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a polar coordinate comparison diagram before and after polygonal wheel shaping using the shaping block shaping portion of Example 1 of the present invention;

[0035] Figure 2 This is a comparison diagram of the non-ovalization amplitude before and after the wheel polygon is modified using the modifying block and modifying portion of Example 1 of the present invention;

[0036] Figure 3 Comparison of wheel circumferential roughness before and after wheel polygonal shaping. DETAILED DESCRIPTION

[0037] Example 1:

[0038] This embodiment proposes a locomotive wheel shaping block, comprising an integrally connected upper shaping portion and a lower support base. The shaping portion comprises the following raw materials, in parts by weight: 12 parts phenolic resin, 2 parts graphite, 11 parts bauxite, 9 parts silicon carbide, 8 parts brass powder, 36 parts iron powder, 10 parts copper fiber, 7 parts steel fiber, 3 parts precipitated barium sulfate, 25 parts nano-SiO2-modified PEEK, and 15 parts graphene-modified PPS. A connecting frame is welded to the back of the support base, through which it is secured to the brake caliper support frame of the bogie. The shaping portion has a concave center portion to adapt and shape the wheel. The thickness ratio of the support base to the shaping portion is 1:2-4. Phenolic resin serves as the bonding matrix, providing high-temperature stability. Graphite acts as a lubricant and friction reducer, reducing the coefficient of friction. Bauxite (Al2O3) is a low-cost, medium-hardness abrasive. Silicon carbide, the primary abrasive, possesses ultra-high hardness (Mohs hardness 9.5).

[0039] To prepare nano-SiO2-modified PEEK, PEEK (polyetheretherketone) particles and modified SiO2 are premixed in a mixer for 10 minutes. The mixture is extruded through a twin-screw extruder with feed section temperatures of 320°C, melt section temperatures of 370°C, homogenization section temperatures of 380°C, and die head temperatures of 350°C. The extruded strands are water-cooled, pelletized, and dried at 120°C for 4 hours. Nano-SiO2, as a hard phase (Mohs hardness 7), forms a protective film on friction surfaces, directly resisting wear.

[0040] To prepare graphene-modified PPS, PPS (polyphenylene sulfide) pellets and reduced graphene oxide are dried at 130°C for 3 hours and premixed in a mixer for 10 minutes. The reduced graphene oxide is fed sideways to prevent shear damage to the reduced graphene oxide structure caused by high temperatures in the main feeding zone. The mixture is extruded through a twin-screw extruder with a feed section temperature of 280°C, a melt section temperature of 300°C, a homogenization section temperature of 305°C, and a die head temperature of 290°C. The extruded strands are water-cooled, pelletized, and dried at 120°C for 4 hours. PPS has a melting point of 280°C and needs to be kept below 310°C to prevent oxidative crosslinking.

[0041] When the nano-SiO2 modified PEEK and graphene modified PPS were extruded and granulated, vacuum devolatilization treatment (-0.08 MPa) was performed to remove volatiles.

[0042] The support base is composed of the following raw materials, measured by weight: 82 parts iron powder, 6 parts copper powder, 2 parts molybdenum powder, 5 parts nickel powder, and 1 part zinc stearate. The support base is manufactured using powder metallurgy technology. Molybdenum powder solid-solution strengthens the iron matrix, improving high-temperature stability, while nickel powder improves toughness and inhibits crack propagation, thereby extending the support base's service life.

[0043] The preparation method of the locomotive wheel shaping block comprises the following steps:

[0044] S1, preparing a trimming blank, including the following steps S11-S14:

[0045] S11, raw material pretreatment:

[0046] The copper fiber and steel fiber were soaked in 5% silane coupling agent ethanol solution for 30 minutes and dried at 90°C. The nano-SiO2 modified PEEK was dried in an oven at 180°C for 3 hours. The graphene modified PPS was milled at low temperature to produce a powder with a particle size of less than 50 μm.

[0047] S12, Mixed:

[0048] Dry mixing stage: first add phenolic resin, graphite, bauxite, silicon carbide and precipitated barium sulfate into a mixer at a speed of 500 rpm and mix for 12 minutes; then add brass powder, iron powder, copper fiber and steel fiber and mix for 4 minutes;

[0049] Wet mixing stage: spray anhydrous ethanol and continue mixing for 15 minutes until the slurry is uniform, then add nano-SiO2 modified PEEK and graphene modified PPS, and mix at 200 rpm for 12 minutes to prepare a mixture;

[0050] S13, hot pressing:

[0051] The mold is preset to 170°C, the mixture is loaded, and pressurized in stages. The first stage is curing at 10MPa and 160°C for 30 minutes, which is pre-curing; the second stage is curing at 30MPa and 180°C for 60 minutes, which is full curing. After full curing, demoulding is carried out. After demoulding, curing is continued at 200°C for 2 hours.

[0052] S14, post-processing:

[0053] A fiber laser is used to machine an array of micron-scale pits on the working surface to produce a trimming blank. The pits have a diameter of 105μm, a depth of 43μm, and a spacing of 208μm, effectively reducing the friction coefficient of the trimming block. Furthermore, ion plating can be performed, and a diamond-like carbon film with a thickness of 2-4μm can be magnetron sputtered on the surface to further reduce adhesive wear.

[0054] S2, preparing a support base blank, including the following steps S21-S24:

[0055] S21. Powder drying:

[0056] Iron powder, copper powder, molybdenum powder and nickel powder were dried under vacuum at 120°C for 2 hours;

[0057] S22, mixing:

[0058] The dried iron powder, copper powder, molybdenum powder and nickel powder were added to a mixer, mixed at a speed of 50 rpm for 2 hours, and then zinc stearate was added and mixed to obtain a mixture;

[0059] S23, compression molding:

[0060] The mixed material was pressed into shape using a hydraulic press at a pressure of 700 MPa and a holding time of 50 seconds to obtain a green material.

[0061] S24, sintering:

[0062] The green material is sintered in four stages using a vacuum sintering furnace, namely: degreasing stage: 300℃, 1 hour; pre-sintering: 800℃, 1 hour; high temperature sintering: 1150℃, 2 hours; slow cooling: the vacuum sintering furnace is cooled to below 200℃ and then taken out of the furnace to obtain the support base blank.

[0063] S3. Overall hot pressing:

[0064] First, the support base blank is placed in the mold, and then the trimming part blank is placed on top of the support base blank. A hot press is used to press the blank at 2000MPa. The entire blank is heated to 850°C and held at this temperature for 30 minutes to obtain the trimming block semi-finished product. To enhance the final hot pressing effect, the support base surface can be sandblasted (Al2O3 sand, particle size 100μm) before hot pressing to increase the bonding area. A 6μm mixture of silane coupling agent and nano-SiO2 is sprayed on the surface and dried at 80°C.

[0065] S4. Overall curing:

[0066] The semi-finished product of the trimming block is placed in a curing oven and cured at 160° C. for 8 hours to obtain a finished product of the trimming block.

[0067] Example 2:

[0068] This embodiment provides a locomotive wheel shaping block, comprising an integrally connected upper shaping portion and a lower support base. The shaping portion comprises the following raw materials, by weight: 14 parts phenolic resin, 4 parts graphite, 10 parts bauxite, 8 parts silicon carbide, 5 parts brass powder, 40 parts iron powder, 16 parts copper fiber, 5 parts steel fiber, 2 parts precipitated barium sulfate, 22 parts nano-SiO2-modified PEEK, and 13 parts graphene-modified PPS. A connecting frame is welded to the back of the support base, through which it is secured to the brake caliper support frame of the bogie. The shaping portion has an inwardly recessed center to provide wheel conformity and shaping. The thickness ratio of the support base to the shaping portion is 1:2-4.

[0069] When preparing nano-SiO2 modified PEEK, PEEK particles and modified SiO2 are premixed in a mixer for 12 minutes; the mixture is extruded through a twin-screw extruder with a feed section temperature of 320°C, a melting section temperature of 370°C, a homogenizing section temperature of 380°C, and a die head temperature of 350°C; the extruded strips are water-cooled and pelletized, and then dried at 120°C for 4 hours.

[0070] When preparing graphene-modified PPS, PPS particles and reduced graphene oxide were dried at 130°C for 3 hours, respectively, and premixed in a mixer for 10 minutes. The reduced graphene oxide was side-fed, and the mixture was extruded through a twin-screw extruder with a feed section temperature of 280°C, a melting section temperature of 300°C, a homogenizing section temperature of 305°C, and a die head temperature of 290°C. The extruded strips were water-cooled and then pelletized and dried at 120°C for 4 hours.

[0071] When the nano-SiO2 modified PEEK and graphene modified PPS were extruded and granulated, vacuum devolatilization treatment (-0.08 MPa) was performed to remove volatiles.

[0072] The support base is composed of the following raw materials, measured by weight: 80 parts iron powder, 7 parts copper powder, 3 parts molybdenum powder, 6 parts nickel powder, and 2 parts zinc stearate. The support base is manufactured using powder metallurgy technology. Molybdenum powder solid-solution strengthens the iron matrix, improving high-temperature stability, while nickel powder improves toughness and inhibits crack propagation, thereby extending the support base's service life.

[0073] The method for preparing a locomotive wheel shaping block comprises the following steps:

[0074] S1, preparing a trimming blank, including the following steps S11-S14:

[0075] S11, raw material pretreatment:

[0076] The copper fiber and steel fiber were soaked in 5% silane coupling agent ethanol solution for 30 minutes and dried at 90°C. The nano-SiO2 modified PEEK was dried in an oven at 180°C for 3 hours. The graphene modified PPS was milled at low temperature to produce a powder with a particle size of less than 50 μm.

[0077] S12, Mixed:

[0078] Dry mixing stage: first add phenolic resin, graphite, bauxite, silicon carbide and precipitated barium sulfate into a mixer at a speed of 500 rpm and mix for 12 minutes; then add brass powder, iron powder, copper fiber and steel fiber and mix for 4 minutes;

[0079] Wet mixing stage: spray anhydrous ethanol and continue mixing for 15 minutes until the slurry is uniform, then add nano-SiO2 modified PEEK and graphene modified PPS, and mix at 200 rpm for 12 minutes to prepare a mixture;

[0080] S13, hot pressing:

[0081] The mold is preset to 170°C, the mixture is loaded, and pressurized in stages. The first stage is curing at 10MPa and 160°C for 30 minutes, which is pre-curing; the second stage is curing at 30MPa and 180°C for 60 minutes, which is full curing. After full curing, demoulding is carried out. After demoulding, curing is continued at 200°C for 2 hours.

[0082] S14, post-processing:

[0083] A fiber laser is used to machine an array of micron-scale pits on the working surface to produce a trimming blank. The pits have a diameter of 105μm, a depth of 43μm, and a spacing of 208μm, effectively reducing the friction coefficient of the trimming block. Furthermore, ion plating can be performed, and a diamond-like carbon film with a thickness of 2-4μm can be magnetron sputtered on the surface to further reduce adhesive wear.

[0084] S2, preparing a support base blank, including the following steps S21-S24:

[0085] S21. Powder drying:

[0086] Iron powder, copper powder, molybdenum powder and nickel powder were dried under vacuum at 120°C for 2 hours;

[0087] S22, mixing:

[0088] The dried iron powder, copper powder, molybdenum powder and nickel powder were added to a mixer, mixed at a speed of 30 rpm for 3 hours, and then zinc stearate was added and mixed to obtain a mixture;

[0089] S23, compression molding:

[0090] The mixed material was pressed and formed using a hydraulic press at a pressure of 600 MPa and a holding time of 60 seconds to obtain a green material.

[0091] S24, sintering:

[0092] The green material is sintered in four stages using a vacuum sintering furnace, namely: degreasing stage: 300℃, 1 hour; pre-sintering: 800℃, 1 hour; high temperature sintering: 1150℃, 2 hours; slow cooling: the vacuum sintering furnace is cooled to below 200℃ and then taken out of the furnace to obtain the support base blank.

[0093] S3. Overall hot pressing:

[0094] First, the support base blank is placed in the mold, and then the trimming part blank is placed on top of the support base blank. A hot press is used to press the blank at 1000MPa. The entire blank is heated to 650°C and held at this temperature for 32 minutes to obtain the trimming block semi-finished product. To enhance the final hot pressing effect, the support base surface can be sandblasted (Al2O3 sand, particle size 100μm) before hot pressing to increase the bonding area. At the same time, an 8μm mixture of silane coupling agent and nano-SiO2 is sprayed on it and dried at 80°C.

[0095] S4. Overall curing:

[0096] The semi-finished product of the trimming block was placed in a curing furnace and cured at 150° C. for 9 hours to obtain a finished product of the trimming block.

[0097] Example 3:

[0098] This embodiment proposes a locomotive wheel shaping block, comprising an integrally connected upper shaping portion and a lower support base. The shaping portion comprises the following raw materials, by weight: 13 parts phenolic resin, 3 parts graphite, 12 parts bauxite, 8 parts silicon carbide, 7 parts brass powder, 38 parts iron powder, 14 parts copper fiber, 6 parts steel fiber, 2 parts precipitated barium sulfate, 20 parts nano-SiO2-modified PEEK, and 10 parts graphene-modified PPS. A connecting frame is welded to the back of the support base, through which it is secured to the brake caliper support frame of the bogie. The shaping portion has an inwardly recessed center to adapt and shape the wheel. The thickness ratio of the support base to the shaping portion is 1:2-4.

[0099] When preparing nano-SiO2 modified PEEK, PEEK particles and modified SiO2 are premixed in a mixer for 11 minutes; the mixture is extruded through a twin-screw extruder with a feed section temperature of 320°C, a melting section temperature of 370°C, a homogenizing section temperature of 380°C, and a die head temperature of 350°C; the extruded strips are water-cooled and pelletized, and then dried at 120°C for 4 hours.

[0100] When preparing graphene-modified PPS, PPS particles and reduced graphene oxide were dried at 130°C for 3 hours, respectively, and premixed in a mixer for 10 minutes. The reduced graphene oxide was side-fed, and the mixture was extruded through a twin-screw extruder with a feed section temperature of 280°C, a melting section temperature of 300°C, a homogenizing section temperature of 305°C, and a die head temperature of 290°C. The extruded strips were water-cooled and then pelletized and dried at 120°C for 4 hours.

[0101] When the nano-SiO2 modified PEEK and graphene modified PPS were extruded and granulated, vacuum devolatilization treatment (-0.08 MPa) was performed to remove volatiles.

[0102] The support base is composed of the following raw materials, measured by weight: 85 parts iron powder, 8 parts copper powder, 2 parts molybdenum powder, 4 parts nickel powder, and 1 part zinc stearate. The support base is manufactured using powder metallurgy technology. Molybdenum powder solid-solution strengthens the iron matrix, improving high-temperature stability, while nickel powder improves toughness and inhibits crack propagation, thereby extending the support base's service life.

[0103] The method for preparing a locomotive wheel shaping block comprises the following steps:

[0104] S1, preparing a trimming blank, including the following steps S11-S14:

[0105] S11, raw material pretreatment:

[0106] The copper fiber and steel fiber were soaked in 5% silane coupling agent ethanol solution for 30 minutes and dried at 90°C. The nano-SiO2 modified PEEK was dried in an oven at 180°C for 3 hours. The graphene modified PPS was milled at low temperature to produce a powder with a particle size of less than 50 μm.

[0107] S12, Mixed:

[0108] Dry mixing stage: first add phenolic resin, graphite, bauxite, silicon carbide and precipitated barium sulfate into a mixer at a speed of 500 rpm and mix for 12 minutes; then add brass powder, iron powder, copper fiber and steel fiber and mix for 4 minutes;

[0109] Wet mixing stage: spray anhydrous ethanol and continue mixing for 15 minutes until the slurry is uniform, then add nano-SiO2 modified PEEK and graphene modified PPS, and mix at 200 rpm for 12 minutes to prepare a mixture;

[0110] S13, hot pressing:

[0111] The mold is preset to 170°C, the mixture is loaded, and pressurized in stages. The first stage is curing at 10MPa and 160°C for 30 minutes, which is pre-curing; the second stage is curing at 30MPa and 180°C for 60 minutes, which is full curing. After full curing, demoulding is carried out. After demoulding, curing is continued at 200°C for 2 hours.

[0112] S14, post-processing:

[0113] A fiber laser is used to machine an array of micron-scale pits on the working surface to produce a trimming blank. The pits have a diameter of 105μm, a depth of 43μm, and a spacing of 208μm, effectively reducing the friction coefficient of the trimming block. Furthermore, ion plating can be performed, and a diamond-like carbon film with a thickness of 2-4μm can be magnetron sputtered on the surface to further reduce adhesive wear.

[0114] S2, preparing a support base blank, including the following steps S21-S24:

[0115] S21. Powder drying:

[0116] Iron powder, copper powder, molybdenum powder and nickel powder were dried under vacuum at 120°C for 2 hours;

[0117] S22, mixing:

[0118] The dried iron powder, copper powder, molybdenum powder and nickel powder were added to a mixer, mixed at a rotation speed of 35 rpm for 2 hours, and then zinc stearate was added and mixed to obtain a mixture.

[0119] S23, compression molding:

[0120] The mixture was pressed and formed by a hydraulic press at a pressure of 650 MPa and a holding time of 55 seconds to obtain a green body.

[0121] S24, sintering:

[0122] The green material is sintered in four stages using a vacuum sintering furnace, namely: degreasing stage: 300℃, 1 hour; pre-sintering: 800℃, 1 hour; high temperature sintering: 1150℃, 2 hours; slow cooling: the vacuum sintering furnace is cooled to below 200℃ and then taken out of the furnace to obtain the support base blank.

[0123] S3. Overall hot pressing:

[0124] First, the support base blank is placed in the mold, and then the trimming part blank is placed on top of the support base blank. A hot press is used to press the blank at 1600MPa. The entire blank is heated to 600°C and held at this temperature for 35 minutes to obtain the trimming block semi-finished product. To enhance the final hot pressing effect, the support base surface can be sandblasted (Al2O3 sand, particle size 100μm) before hot pressing to increase the bonding area. A 7μm-thick mixture of silane coupling agent and nano-SiO2 is sprayed on the surface and dried at 80°C.

[0125] S4. Overall curing:

[0126] The semi-finished product of the trimming block is placed in a curing oven and cured at 140° C. for 8 hours to obtain a finished product of the trimming block.

[0127] Comparative Example:

[0128] This embodiment provides a locomotive wheel shaping block, comprising an upper shaping portion and a lower support seat integrally connected. The shaping portion comprises the following raw materials, measured by weight: 13 parts phenolic resin, 3 parts graphite, 10 parts bauxite, 8 parts silicon carbide, 7 parts brass powder, 38 parts iron powder, 14 parts copper fiber, 5 parts steel fiber, and 3 parts precipitated barium sulfate.

[0129] The support base includes the following raw materials in parts by weight: 83 parts of iron powder, 7 parts of copper powder and 1 part of zinc stearate. The support base is prepared by using powder metallurgy technology.

[0130] The method for preparing a locomotive wheel shaping block comprises the following steps:

[0131] S1, preparing a trimming blank, including the following steps S11-S13:

[0132] S11, raw material pretreatment:

[0133] The copper fiber and steel fiber were soaked in 5% silane coupling agent ethanol solution for 30 minutes and dried at 90°C;

[0134] S12, Mixed:

[0135] First, add phenolic resin, graphite, bauxite, silicon carbide and precipitated barium sulfate to a mixer at 500 rpm and mix for 10 minutes; then add brass powder, iron powder, copper fiber and steel fiber and mix for 4 minutes;

[0136] S13, hot pressing:

[0137] The mold is preset to 165°C, the mixture is loaded, and pressurized in stages. The first stage is curing at 10MPa and 160°C for 30 minutes, which is pre-curing; the second stage is curing at 30MPa and 180°C for 60 minutes, which is full curing. After full curing, demoulding is carried out. After demoulding, it is cured at 200°C for 2 hours.

[0138] S2, preparing a support base blank, including the following steps S21-S24:

[0139] S21. Powder drying:

[0140] The iron powder and copper powder were vacuum dried at 120 °C for 2 h;

[0141] S22, mixing:

[0142] The dried iron powder and copper powder were added to a mixer, mixed at a speed of 40 rpm for 2 hours, and then zinc stearate was added and mixed to obtain a mixture;

[0143] S23, compression molding:

[0144] The mixed material was pressed into shape using a hydraulic press at a pressure of 650 MPa and a holding time of 55 seconds to obtain a green material.

[0145] S24, sintering:

[0146] The green material is sintered in four stages using a vacuum sintering furnace, namely: degreasing stage: 300℃, 1 hour; pre-sintering: 800℃, 1 hour; high temperature sintering: 1150℃, 2 hours; slow cooling: the vacuum sintering furnace is cooled to below 200℃ and then taken out of the furnace to obtain the support base blank.

[0147] S3. Overall hot pressing:

[0148] First, place the support seat blank into the mold, then place the trimming part blank onto the support seat blank, and use a hot press to press it at 1200MPa. Heat the entire blank to 650°C and keep it warm for 32 minutes to obtain a trimming block semi-finished product.

[0149] S4. Overall curing:

[0150] The semi-finished product of the trimming block is placed in a curing oven and cured at 140° C. for 8 hours to obtain a finished product of the trimming block.

[0151] The trimming block samples prepared in Examples 1 to 3 and the comparative example were taken, and the trimming portions of the trimming block samples were subjected to performance tests of various indicators according to the test standards in Table 1. The specific test results are shown in Table 2.

[0152] Table 1: Test standards

[0153] Basic parameters Reference Standards Hardness (HRR) GB / T3398.2-2008 <![CDATA[Impact strength (kJ / m 2 )]]> GB / T1043.1-2008 Compression strength (MPa) GB / T1041-2008 <![CDATA[Density (g / cm 3 )]]> GB / T1033.1-2008 Wear GB5763-2008 Friction coefficient GB5763-2008

[0154] Table 2: Test results

[0155]

[0156] Compared with the shaping blocks of the comparative examples, the shaping blocks in Examples 1 to 3 of the present invention have lower wear and friction coefficients, as well as higher impact strength, good wear resistance, long service life, and high safety. In Examples 1 to 3, wear resistance is enhanced by modifying PEEK with nano-SiO2, and the wear rate is low. Toughening is achieved by modifying PPS with graphene, and the impact strength is improved. In addition, graphene-modified PPS can also improve the thermal conductivity of the shaping block, achieve efficient heat dissipation, and reduce heat accumulation. In the raw materials of the support seat, molybdenum powder can solid-solution strengthen the iron matrix and improve high-temperature stability, and nickel powder can improve toughness and inhibit crack propagation, thereby increasing the service life of the support seat.

[0157] The test results of using the shaping block of Example 1 to shape a locomotive wheel set are as follows: During the test, there are two control modes: in the first control mode, the initial speed is decelerated from 350km / h to 0, and the shaping part of the shaping block is used to continuously shape the wheel within the speed range of 350-30km / h, and this is repeated 95 times, with a polygon measurement performed every 5 times. In the second control mode, the initial speed is decelerated from 300km / h to 0, and the shaping part of the shaping block is used to continuously shape the wheel within the speed range of 300-30km / h, and this is repeated 80 times, with a polygon measurement performed every 5 times. Figure 1-Figure 3 As shown in the figure, under the action of the shaping part, after 175 braking shapings, the wave depth of the 18-order polygon generated in the actual operation of the wheel is reduced from 0.035mm to 0.020mm, the non-ovalization amplitude of the wheel is reduced from 0.016mm to 0.009mm, and the circumferential roughness of the wheel is reduced from 26dB to 19dB.

[0158] In summary, the shaping block effectively reduces the polygonal wave depth, non-elliptical amplitude and surface roughness of the wheel during operation, and has a good shaping effect.

[0159] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A locomotive wheel shaping block, characterized in that: It includes an upper shaping portion and a lower supporting seat integrally connected; The shaping part includes the following raw materials in parts by weight: 12-14 parts of phenolic resin, 2-4 parts of graphite, 10-12 parts of bauxite, 8-9 parts of silicon carbide, 5-8 parts of brass powder, 36-40 parts of iron powder, 10-16 parts of copper fiber, 5-7 parts of steel fiber, 2-3 parts of precipitated barium sulfate, 20-25 parts of nano-SiO2 modified PEEK and 10-15 parts of graphene modified PPS; The support seat comprises the following raw materials in parts by weight: 80-85 parts of iron powder, 6-8 parts of copper powder, 2-3 parts of molybdenum powder, 4-6 parts of nickel powder and 1-2 parts of zinc stearate.

2. The locomotive wheel shaping block according to claim 1, characterized in that: When preparing nano-SiO2 modified PEEK, PEEK particles and modified SiO2 are premixed in a mixer for 10-12 minutes; the mixture is extruded through a twin-screw extruder with a feed section temperature of 320°C, a melting section temperature of 370°C, a homogenizing section temperature of 380°C, and a die head temperature of 350°C; the extruded strips are water-cooled and pelletized, and then dried at 120°C for 4 hours.

3. The locomotive wheel shaping block according to claim 2, characterized in that: When preparing graphene-modified PPS, PPS particles and reduced graphene oxide were dried at 130°C for 3 hours, premixed in a mixer for 10 minutes, and extruded through a twin-screw extruder with a feed section temperature of 280°C, a melting section temperature of 300°C, a homogenizing section temperature of 305°C, and a die head temperature of 290°C. The extruded strips were water-cooled and pelletized, and then dried at 120°C for 4 hours.

4. The locomotive wheel shaping block according to claim 3, characterized in that: When preparing graphene-modified PPS, the graphene oxide was reduced using a side feeding method.

5. The locomotive wheel shaping block according to claim 3, characterized in that: During the extrusion granulation of nano-SiO2 modified PEEK and graphene modified PPS, vacuum devolatilization treatment is performed to remove volatiles.

6. A method for preparing a locomotive wheel shaping block according to claim 1, characterized in that: The following steps are involved: S1, preparing a trimming blank, including the following steps S11-S13: S11, raw material pretreatment: The copper fiber and steel fiber were soaked in 5% silane coupling agent ethanol solution for 30 minutes and dried at 90°C. The nano-SiO2 modified PEEK was dried in an oven at 180°C for 3 hours. The graphene modified PPS was milled at low temperature to produce a powder with a particle size of less than 50 μm. S12, Mixed: Dry mixing stage: first add phenolic resin, graphite, bauxite, silicon carbide and precipitated barium sulfate into a mixer at a speed of 500 rpm and mix for 10-12 minutes; then add brass powder, iron powder, copper fiber and steel fiber and mix for 4-6 minutes; Wet mixing stage: spray anhydrous ethanol and continue mixing for 15-17 minutes until the slurry is uniform, then add nano-SiO2 modified PEEK and graphene modified PPS, and mix at 200 rpm for 10-12 minutes to prepare a mixture; S13, hot pressing: The mold is preset to 160-170°C, the mixture is loaded, and pressurized in stages. The first stage is cured at 10MPa and 160°C for 30 minutes, which is pre-curing; the second stage is cured at 30MPa and 180°C for 60 minutes, which is full curing. After full curing, demoulding is performed to obtain the blank of the trimming part; S2, preparing a support base blank, including the following steps S21-S24: S21. Powder drying: Iron powder, copper powder, molybdenum powder and nickel powder were dried under vacuum at 120°C for 2 hours; S22, mixing: Add the dried iron powder, copper powder, molybdenum powder and nickel powder to a mixer, mix at a speed of 30-50 rpm for 2-3 hours, then add zinc stearate and mix to obtain a mixture; S23, compression molding: The mixed material is pressed into shape using a hydraulic press at a pressure of 600-700 MPa and a holding time of 50-60 seconds to obtain a green material; S24, sintering: The green material was sintered in four stages using a vacuum sintering furnace, namely: debinding stage: 300 °C, 1 hour; Pre-sintering: 800℃, 1 hour; high temperature sintering: 1150℃, 2 hours; Slow cooling: When the vacuum sintering furnace cools to below 200℃, the support base blank is obtained; S3. Overall hot pressing: Place the trimming part blank on the support base blank, and use a hot press to press it at 1000-2000 MPa. Heat the entire blank to 600-850°C and keep it warm for 30-35 minutes to obtain a trimming block semi-finished product. S4. Overall curing: The semi-finished product of the trimming block is placed in a curing oven and cured at 140-160° C. for 8-9 hours to obtain a finished product of the trimming block.

7. The preparation method according to claim 6, characterized in that The preparation steps of the blank of the trimming part also include S14, post-processing: using a fiber laser to process a micron-level pit array on the working surface, with a pit diameter of 100-110 μm, a depth of 40-50 μm, and a spacing of 200-220 μm.

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