Grinding unit for high speed train and preparation method of grinding unit
A technology for high-speed EMUs and abrasives, which can be used in vehicle maintenance, vehicle cleaning, metal processing equipment, etc., and can solve the problems that the application is not fully mature.
Active Publication Date: 2018-11-20
中申(上海)管道工程股份有限公司
6 Cites 19 Cited by
AI-Extracted Technical Summary
Problems solved by technology
[0006] However, since the grinding sub-products are only used on specific high-speed train models, they have not been fully popularized ...
Method used
In the present invention, contriver finds through long-term study, when powdered acrylonitrile-butadiene rubber is nanoscale, the friction material distribution of the grinder of preparation is uniform, and each physics and mechanical property, friction performance have obvious improvement: inventor It is found that, compared with non-nano-scale powdered nitrile rubber, the grinding wheel is prepared by using nano-scale powdered nitrile rubber, the stability of its friction coefficient is increased by two times, the thermal stability is increased by 1.5 times, the friction noise is reduced by 20%, and it is not easy to produce cracks. Blocks and metal inlays, no abnormal wear on the frictional dual surfaces.
In the present invention, the contriver finds through long-term research, and the raw material of described friction material comprises reduced iron powder; When milling child and wheel contact friction, described reduced iron powder and oxidized particle can adhere to wheel surface, It will improve the adhesion of the wheel, so as to achieve the purpose of thickening; at the same time, the iron powder is conducive to improving the thermal conductivity of the product, reducing the friction surface temperature, and improving the friction stability; using the reduced iron powder in the above range, the prepared abrasive Well, the loss of the wheel is small, the wheel is protected from deformation, and a balance can be achieved between the modification and the loss; specifically, the invention selects different iron powder contents according to the wheel material, vehicle speed and ambient temperature, and obtains the prepared grinding wheel A balance is achieved between wheel cleaning and wheel wear; the present invention is optimized, and the Fe3O4 content in the reduced iron powder needs to be more than 91%; the present invention is optimized, and the reduced iron powder consumption is 56%.
In the present invention, the contriver finds through long-term research, described metal fiber is taken from one or more in the metal fiber such as copper or iron, solves the high strength, high elasticity that the prepared abrasive sub-requires Good modulus, thermal stability, good adsorption, anti-fatigue and anti-wear performance requirements, and eliminate the problems of metal inlay and wheel tread thermal cracks of the prepared grinding wheel.
In the present invention, the contriver finds through long-term study, what described mineral fib...
Abstract
The invention provides a grinding unit for a high speed train and a preparation method of the grinding unit. The grinding unit is composed of a friction material and a steel backing, wherein the friction material is composed of phenolic resins having specific physical properties, reinforced fibers, fillers and the like; the components of the friction material need to be pretreated such as mixing and drying; the steel backing needs to be pretreated such as abrasive blasting and resin glue spraying; the pretreated friction material and steel backing are subjected to special hot press molding, heat treatment and other processes, thereby obtaining the grinding unit. According to the grinding unit disclosed by the invention, by improving the thermal stability and enhancing the shock strength, the performance of the grinding unit in aspects such as metal inlaying, crack chipping, wheel shaping, friction noise and the like are improved, damage to the wheel tread is small, the phenomena such as hot cracks and severe wave furrowed abrasion are difficultly caused, and the grinding unit has important application value and wide market prospects in the field of high-speed trains.
Application Domain
Metal-working apparatusVehicle cleaning
Technology Topic
Hot pressHigh speed train +10
Image
Examples
- Experimental program(8)
Example Embodiment
[0054] The present invention provides a method for preparing a grinding wheel for high-speed EMUs, which includes the following steps: selected raw materials are made by weighing, mixing, steel back surface treatment, spraying, hot pressing, and heat treatment according to the ratio. The specific steps are as follows :
[0055] 1) Weighing:
[0056] According to the ratio of the raw materials of the grinding parts, use an electronic scale with a suitable range and precision to accurately weigh the required amount of materials; different raw materials are placed in different labeled material boxes and recorded for easy traceability.
[0057] 2) Mixing:
[0058] a) The plow-type mixer is used for the mixing of the present invention, which can solve the mixing uniformity problems of most non-asbestos mineral fibers and organic fibers with fillers, resins, and powder rubbers.
[0059] b) Put the prepared materials into the mixer and close the feed inlet; set the coulter to run for 20-25 minutes, and the high-speed stirring knife to run for 15-18 minutes;
[0060] c) After the mixing is finished, sample the mixture to visually inspect the uniformity, and it is required to mix evenly without obvious fiber agglomeration.
[0061] d) Dry the mixture in an oven at a temperature of 85±10°C.
[0062] 3) Steel back surface treatment and glue spraying:
[0063] In order to remove impurities such as oil and rust on the steel back and improve the adhesion of the spray glue, the steel back needs to be sandblasted, and then the resin glue is evenly sprayed on the contact surface between the steel back and the friction material (resin: alcohol weight ratio = 1:1~1 :2. Adjust according to temperature), dry naturally, and prevent dust and other impurities from polluting the spray surface.
[0064] 4) Hot pressing:
[0065] Clean the cavity of the mold with compressed air before pressing, then preheat the mold on the heating platform, after preheating to the set temperature, spray the water-based release agent evenly on the cavity of the mold, and then evenly add the mixture obtained from step 2) , And then put the steel back treated from step 3) lightly on top of the mixture in the mold cavity, start the program, start to press, press after the pressure-holding-exhaust cycle and then hold and solidify until the program is completed, take out the product, After passing the inspection, transfer to the next process.
[0066] A 200T ton four-column hydraulic press is used for the grinding mill. The specific pressing parameters are as follows: pressing temperature 150~160℃; press pressure: 4~5Mpa; pressure holding-exhausting parameters: holding time 40~50 seconds, exhaust time 10~15 Seconds, hold pressure-exhaust 4-6 times; hold pressure curing time: 1200-1500 seconds.
[0067] Phenolic resin undergoes polycondensation reaction at a certain pressing temperature and becomes an infusible and insoluble cured product with a network cross-linked structure. This process is irreversible; if the pressing temperature is too high, the resin will cure too fast and the fluidity of the rubber compound will decrease. It can be cured before the cavity is evenly filled, resulting in defects or looseness in the corners of the product, and the mechanical strength is affected; the temperature is too low, the curing speed is too slow, the production efficiency is low, the product is soft, and the internal moisture and total volatile vapors Under the action of pressure, bubble defects appear; therefore, temperature control is very important; the present invention is optimized, and the pressing temperature is 150-160°C.
[0068] The pressing pressure and the molding temperature are equally important. If the pressure is too low, the product will have poor compactness, loose texture, uneven thickness, and corner defects; too high pressure will not only make the product hardness too high, the compression modulus will be too large, which will affect the performance, but also Increase the energy consumption, cause damage to the mold and the press and the edge of the product to be scrapped; the present invention is optimized, and the pressing pressure is 4-5Mpa.
[0069] After the first pressurization, the pressure needs to be released, and the moisture, free formaldehyde, ammonia and other volatiles generated in the rubber compound and during the curing process are discharged out of the mold, so as to avoid defects such as foaming, swelling, and cracking of the product under the action of huge vapor pressure. This operation is called exhaust. At this time, the rubber is in a plastic state; exhaust is too late, because the phenolic resin has solidified, the high-pressure gas is difficult to discharge, causing internal swelling and cracking. The pressure-holding curing time after exhausting needs to be calculated according to the thickness of the product. The thicker the product, the slower the internal heating, and the longer the time to fully cure; the pressure-holding-exhausting parameter is: pressure-holding time 40 ~50 seconds, exhaust time 10-15 seconds, pressure-exhaust 4-6 times; pressure-hold curing time: 1200-1500 seconds.
[0070] This pressing parameter is a preferred parameter. It has been verified by experiments that the synthetic abrasive has excellent friction and wear performance and good thermal stability.
[0071] 5) Heat treatment:
[0072] The pressed grindstones are flatly discharged in the solidification furnace material rack with a minimum interval of 10mm to ensure smooth flow of hot air and uniform temperature throughout the furnace. Run in accordance with the set heat treatment curve program, the heat treatment program described in accordance with the attached figure 1 The parameters set the heat treatment process. After the program runs, let it cool to below 50°C and open the furnace door to take out the product.
[0073] After the heat treatment, check the appearance of the grindstone and there should be no defects such as blistering, cracks, delamination, looseness, warpage, etc.; the friction material and the steel back should be closely integrated.
[0074] The purpose of the heat treatment: (1) to completely cure the resin in the product to stabilize its performance; (2) to eliminate the thermal stress of the product after hot pressing and prevent the product from warping and deformation; (3) to reduce the thermal expansion of the product.
[0075] The parameter requirements of the heat treatment curve program of the grinder of the present invention need to meet the attached figure 1 The curve shown.
[0076] In the present invention, in the step 4) hot pressing, during the pressing process, the pressing time, temperature, pressure and other parameters should be controlled, and the surface of the product should be smooth and flat, and the friction body should not have cracks or cracks. For defects such as bubbles, delamination, looseness and warpage, the friction material and the steel back should be tightly combined; the pressing time is too short, it will cause the product to become soft, the texture is coarse, blistering, swelling, cracks, etc.; If the temperature is too high, it will cause defects in the edges and corners of the product, uneven texture, blistering, swelling, and cracks on the surface; if the pressing temperature is too low, it will cause the product to become soft, whitish, dull, and affect the appearance; If the number of times is less than the specified number, it will cause defects such as cracks, blistering, delamination, porosity, and warpage; the exhaust time less than the specified time will cause defects such as cracks, blistering, delamination, porosity, and warpage.
[0077] In step 5) of the present invention, during the heat treatment, the temperature rise rate is faster than that of the attached figure 1 Curve speed, the product will foam and deform; holding time is less than attached figure 1 During the period, the product becomes soft, coarse in texture, blisters, swelling, cracks, etc.
[0078] The invention provides a grinder for a high-speed EMU and a preparation method thereof. The grinder is composed of a steel back and a friction material, and the steel back and the friction material are bonded together by hot pressing. The steel back is made of steel plate with mechanical properties not lower than Q235-A. The friction material is mainly made of phenolic resin, reinforcing fibers and fillers through weighing, mixing, hot pressing, and heat treatment. It does not contain asbestos, cadmium, and mercury. , Chromium or its compounds, and other materials that may generate harmful gases and dust; the prepared grinder has no cracks or lumps, low wear, low braking noise, no metal inlay, good repairability to the wheel, and damage to the wheel tread Small, no thermal cracks, serious wave furrow-like wear and other phenomena.
Example Embodiment
[0082] Embodiment 1. An abrasive for high-speed EMUs and its preparation method
[0083] An abrasive for high-speed EMUs. The abrasive is composed of a steel back and a friction material. The friction material includes the following raw materials and weight ratios, as shown in Table 1.
[0084] Table 1. Raw materials and weight ratio of friction materials
[0085] Serial number
[0086] The method for preparing an abrasive for high-speed EMUs includes the following steps: the selected raw materials are made by weighing, mixing, steel back surface treatment, spraying, hot pressing, and heat treatment according to the weight ratio. Proceed as follows:
[0087] 1) Weighing:
[0088] According to the ratio of friction material raw materials, use an electronic scale with appropriate range and accuracy to accurately weigh the required amount of material; different raw materials are placed in different labeled material boxes and recorded for easy traceability.
[0089] 2) Mixing:
[0090] a) Put the prepared materials into the rake mixer and close the feed inlet; set the coulter to run for 20 minutes and the high-speed stirring knife to run for 18 minutes;
[0091] b) Dry the mixture in an oven at a drying temperature of 75°C.
[0092] 3) Steel back surface treatment and glue spraying:
[0093] Sandblast the steel back, and then evenly spray resin glue (resin:alcohol weight ratio = 1:1) on the contact surface of the steel back and the friction material, and dry it naturally to prevent dust and other impurities from polluting the spray surface.
[0094] 4) Hot pressing:
[0095] Clean the cavity of the mold with compressed air before pressing, and then preheat the mold on the heating platform. After preheating to the set temperature, spray the water-based release agent evenly on the cavity of the mold, and then evenly add the 1.24kg mixture, and then Put the grinder holder into the mold cavity lightly, start the program, start pressing, after pressing the pressure-holding-exhaust cycle, the pressure is maintained and solidified until the program is completed, the product is taken out, and the inspection is passed to the next process.
[0096] A 200T ton four-column hydraulic press is used for the pressing. The pressing parameters are as follows: pressing temperature 150°C; press pressure: 4Mpa; pressure-holding-exhaust parameters: pressure-holding time 40 seconds, exhaust time 10 seconds, pressure-holding-exhausting 4 times; Holding pressure curing time: 1200 seconds.
[0097] 5) Heat treatment:
[0098] Place the pressed grinder in the solidification furnace rack to ensure that the hot air flows smoothly and the temperature in the furnace is uniform; run according to the set heat treatment curve program, and the heat treatment curve program parameters must meet the attached figure 1 Requirement of the curve; after the program runs, open the furnace door and take out the product after cooling to below 50℃.
Example Embodiment
[0099] Embodiment 2. A grinding wheel for high-speed EMUs and its preparation method
[0100] An abrasive for high-speed EMUs. The abrasive is composed of a steel back and a friction material. The friction material includes the following raw materials and weight ratios, as shown in Table 2.
[0101] Table 2. The raw material and weight ratio of friction materials
[0102] Serial number
[0103] The method for preparing an abrasive for high-speed EMUs includes the following steps: the selected raw materials are made by weighing, mixing, steel back surface treatment, spraying, hot pressing, and heat treatment according to the weight ratio. Proceed as follows:
[0104] 1) Weighing:
[0105] According to the ratio of friction material raw materials, use an electronic scale with appropriate range and accuracy to accurately weigh the required amount of material; different raw materials are placed in different labeled material boxes and recorded for easy traceability.
[0106] 2) Mixing:
[0107] a) Put the prepared materials into the rake mixer and close the feed inlet; set the coulter to run for 25 minutes and the high-speed stirring knife to run for 15 minutes;
[0108] b) After the mixing is finished, the mixing should be uniform without obvious fiber agglomeration; otherwise, return to step a) for processing again.
[0109] c) Dry the mixture in an oven at a drying temperature of 80°C.
[0110] 3) Steel back surface treatment and glue spraying:
[0111] Sandblast the steel back, and then evenly spray resin glue (resin: alcohol weight ratio = 1:2) on the contact surface of the steel back with the friction material, and let it dry naturally to prevent dust and other impurities from polluting the spray surface.
[0112] 4) Hot pressing:
[0113] Clean the cavity of the mold with compressed air before pressing, and then preheat the mold on the heating platform. After preheating to the set temperature, spray the water-based release agent evenly on the cavity of the mold, and then evenly add the 1.23kg mixture, and then Put the grinder holder into the cavity lightly, start the program, and start pressing. After pressing the pressure-holding-exhaust cycle, the pressure is maintained and solidified until the program is completed, the product is taken out, and the inspection is passed to the next process.
[0114] A 200T ton four-column hydraulic press is used for the pressing. The pressing parameters are as follows: pressing temperature 160°C; press pressure: 5Mpa; pressure-holding-exhausting parameters: pressure-holding time 50 seconds, exhaust time 15 seconds, pressure-holding-exhausting 6 times; Holding pressure curing time: 1500 seconds.
[0115] 5) Heat treatment:
[0116] Place the pressed grinder in the solidification furnace rack to ensure that the hot air flows smoothly and the temperature in the furnace is uniform; run according to the set heat treatment curve program, and the heat treatment curve program parameters must meet the attached figure 1 Requirement of the curve; after the program runs, open the furnace door and take out the product after cooling to below 50℃.
PUM
| Property | Measurement | Unit |
| Liquidity | 25.0 ~ 40.0 | mm |
| Fineness | >= 100.0 | mesh |
| Fineness | >= 325.0 | mesh |
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