A reinforcing method for high-speed worm grinding wheel

Abstract

The application discloses a reinforcing method for high-speed worm grinding wheel, which comprises the following steps: 1) a worm grinding wheel blank is prepared by using a dynamic balance forming technology, and the worm grinding wheel blank is dried and sintered; 2) a ceramic binder sol is prepared; 3) the ceramic binder sol prepared in the step 2) is uniformly impregnated around a central hole of the worm grinding wheel prepared in the step 1), and the worm grinding wheel for gear grinding is obtained after sintering. The worm grinding wheel prepared by the method has a static unbalance weight of less than or equal to 10 g, and the use linear speed of the worm grinding wheel can reach 80 m / s to 100 m / s through the impregnation reinforcement of the ceramic binder sol, so that the method has the advantages of simple production process, high grinding efficiency and high grinding precision.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of grinding wheel manufacturing, and particularly relates to a reinforcing method for high-speed worm grinding wheel for gear grinding. BACKGROUND

[0002] In recent years, with the rapid development of new energy vehicles in China, the machining precision and grinding efficiency of traditional automobile gearbox gears cannot meet the requirements of new energy vehicles on gear precision, meshing, running noise, running stability and service life. In order to improve the machining precision and grinding efficiency, the domestic gear industry has successively introduced Hoefler, Reishauer, Kapp and Gleason high-precision, high-speed and high-efficiency worm gear grinding machines from developed countries such as Germany, Switzerland and the United States. With the continuous improvement of worm grinding machines and the development of grinding technology, worm grinding wheels are also forced to develop in the direction of high strength and high linear speed, so as to match the high-efficiency gear grinding machines. However, the strength of all domestic and part of imported worm grinding wheels used in the domestic gear industry is low, the maximum linear speed is 80 m / s, and the advantages of imported worm gear grinding machines cannot be fully utilized, which seriously affects the precision and production efficiency of gear machining in China.

[0003] The traditional method for improving the strength of worm grinding wheels is to increase the amount of binder and improve the molding density. Although this method can improve the strength of worm grinding wheels, the worm grinding wheels prepared by this method have high hardness and low porosity, and the problem of workpiece burning may occur during high-speed grinding. Chinese patent CN103862393A discloses a ceramic microcrystalline abrasive gear grinding wheel, which comprises a center reinforcing part and a grinding use part. The preparation method of the grinding wheel disclosed in the patent inevitably causes the center reinforcing part to extrude the outer grinding use part during the pressing process, resulting in the intersection of the core material and the outer material. This situation may cause two problems in the sintered grinding wheel: first, the grinding wheel is not balanced, and the tooth shape and tooth direction cannot meet the requirements when the grinding speed is increased, and more seriously, the grinding wheel may be broken; second, the center reinforcing part has large density and the grinding use part has small density, and large internal stress may be generated due to the inconsistent shrinkage of the inside and outside during high-temperature sintering, resulting in cracks in the grinding wheel. SUMMARY

[0004] The present application aims to provide a reinforcing method for high-speed worm grinding wheel, which uses abrasive, binder, adhesive, wetting agent and pore-forming agent as raw materials, and uses dynamic balance forming technology to prepare worm grinding wheel, and uses ceramic binder sol to impregnate the center of worm grinding wheel, and then sintering to improve the overall strength and linear speed of the grinding wheel.

[0005] To achieve the above object, the present application uses the following technical scheme:

[0006] A reinforcing method for high-speed worm grinding wheel, comprising the following steps:

[0007] (1) Preparation of worm grinding wheel: pour the molding material into the rotating mold, use the abrasive dynamic balance forming technology to make the molding material evenly distributed in the mold, then press into a grinding wheel blank, dry and sinter to obtain the worm grinding wheel;

[0008] (2) Preparation of ceramic binder sol: add borax to aluminum sol to obtain sol A; add lithium salt to silicon sol to obtain sol B; mix sol A and sol B evenly, then add nano-ZrO2 and nano-ZnO, stir evenly to obtain ceramic binder sol, wherein the weight fraction of each raw material is shown in the following table:

[0009] Aluminum sol Silica sol Borax Lithium salt nano-ZrO2 Nano-ZnO 20~40 parts 30~60 parts 5~10 parts 1~5 parts 2~5 parts 2~5 parts

[0010] (3) Pour the ceramic binder sol prepared in step (2) into the inner hole of the grinding wheel to impregnate the inner hole of the grinding wheel in the ceramic binder, the impregnation time is 20-40 min, and then sinter to obtain the high-speed worm grinding wheel for gear grinding.

[0011] The principle of the abrasive dynamic balance forming technology is: during the forming of the abrasive, after the processes of feeding, raking and scraping, the sensor detects the phase and size of the radial imbalance of the molding material in the rotating mold, and the corresponding amount of molding material is added or subtracted by manual or auxiliary device to improve the radial mass distribution of the molding material in the mold relative to the axis, so as to achieve the purpose of dynamic balance of the molding material in the mold, thereby greatly reducing the imbalance value after the formation of the grinding wheel and improving the balance of the grinding wheel itself.

[0012] Preferably, the rotation rate of the abrasive in step (1) is 10-50 rpm / min.

[0013] Preferably, the drying temperature of the grinding wheel blank in step (1) is 100-120℃, the heating rate is 0.1-0.5℃ / min, and the holding time is 2-4h.

[0014] Preferably, the sintering temperature of the grinding wheel blank in step (1) is 1000-1300℃, the heating rate is 1-5℃ / min, and the holding time is 2-4h.

[0015] Preferably, the solid content of the aluminum sol in step (2) is 15-35wt%, and the colloidal particle size is 20-80nm; the solid content of the silicon sol is 20-50wt%, and the colloidal particle size is 50-100nm.

[0016] Preferably, the lithium salt in step (2) is LiNO3, Li2CO3, Li2SO4, or a mixture of two or more thereof in any ratio; the particle size of nano-ZrO2 is 1-100nm, and the particle size of nano-ZnO is 1-100nm.

[0017] Preferably, the sintering temperature in step (3) is 800-1000℃, the heating rate is 1-5℃ / min, and the holding time is 1-2h.

[0018] The forming material is a prior art, such as the following formula, in mass percentage: abrasive 80-90%, binder 10-20%, added with binder 2-4%, humectant 2-4%, and pore-forming agent 1-5%, based on the total weight of the abrasive and the binder.

[0019] The abrasive is one or a mixture of more than one of white corundum, chromium corundum, single crystal corundum, and ceramic microcrystalline corundum. Preferably, the particle size of the abrasive is 80-100 mesh.

[0020] The binder is a boron-lithium low-temperature binder, consisting of, in parts by weight: clay 20-35 parts, feldspar 25-40 parts, boron glass 15-30 parts, and lithium carbonate 1-6 parts.

[0021] The binder is dextrin powder.

[0022] The humectant is a sucrose aqueous solution or a dextrin aqueous solution, with a weight fraction of 30%. The pore-forming agent is refined naphthalene or walnut powder.

[0023] The beneficial effects of the present application are: (1) the present application adopts the abrasive tool dynamic balance forming technology, the prepared worm gear grinding wheel has good balance, avoids the poor balance caused by the extrusion intersection of the core material and the outer material in the patent CN103862393A, and avoids the cracking and breaking problems caused by the inconsistent inner and outer shrinkage. (2) the ceramic binder sol is used to impregnate the center hole of the worm gear grinding wheel, can fully fill each gap, effectively connects each abrasive, improves the holding force of the binder to the abrasive, and the prepared worm gear grinding wheel has the characteristics of low density and high strength, compared with other worm gear grinding wheels without reinforcing method, the strength is obviously improved, can be matched with imported high-speed grinding gear machine tool, improves the machining precision and production efficiency. DETAILED DESCRIPTION

[0024] The present application will be further explained in combination with specific embodiments. In each of the following examples and comparative examples, the composition of the molding material is: 84wt% 80 mesh white corundum and 16wt% binder, and then 3% dextrin powder 3% dextrin liquid (30wt%), 1% refined naphthalene is added, accounting for the total weight of white corundum and binder; the composition of the binder is: clay 29 parts by weight, feldspar 38 parts by weight, boron glass 29 parts by weight, lithium carbonate 4 parts by weight. In the ceramic binder sol of each of the following examples, the particle size of the colloidal particles in the sol and the silica sol is 50 nm, and the particle size of the nano ZrO2 and the nano ZnO is 80 nm.

[0025] Example 1

[0026] A reinforcing method for high-speed worm grinding wheel for gear grinding, the specific steps are as follows:

[0027] (1) Preparation of worm grinding wheel: pour the molding material into the mold with a rotation speed of 30 rpm / min, use the abrasive tool dynamic balance forming technology to make the molding material uniformly distributed in the mold, then perform pressure forming, and dry and sinter to obtain the worm grinding wheel. The pressure of the pressure forming is 5MPa, and the pressure holding time is 20s; the drying temperature is 120℃, the heating rate is 0.5℃ / min, and the holding time is 4h. The sintering temperature is 1300℃, the heating rate is 5℃ / min, and the holding time is 4h.

[0028] (2) Preparation of ceramic binder sol: 10 parts by weight of borax is added to 20 parts by weight of aluminum sol with a solid content of 25wt%, and after sufficient dissolution, sol A is obtained; 3 parts by weight of LiNO3 is added to 60 parts by weight of silica sol with a solid content of 25wt%, and after sufficient sol, sol B is obtained; 30 parts by weight of sol A and 63 parts by weight of sol B are mixed uniformly, then 3 parts by weight of nano ZrO2 and 2 parts by weight of nano ZnO are added in turn and stirred uniformly to obtain the ceramic binder sol.

[0029] (3) Pour the ceramic binder sol prepared in step (2) into the inner hole of the grinding wheel in step (1) to immerse the inner hole of the grinding wheel in the ceramic binder, the immersion time is 30 min, and the high-speed worm grinding wheel for gear grinding is obtained after sintering, the thickness of the ceramic binder layer is 15 mm, wherein the sintering temperature is 850°C, the heating rate is 5°C / min, and the holding time is 1 h.

[0030] Example 2

[0031] A reinforcing method for a high-speed worm grinding wheel for gear grinding, the specific steps are as follows:

[0032] (1) Preparation of worm grinding wheel: Pour the molding material into the mold with a rotation speed of 30 rpm / min, uniformly distribute the molding material in the mold by using the dynamic balance molding technology of grinding tool, then perform press molding, and dry and sinter to obtain the worm grinding wheel. The pressure of the press is 5 MPa, the pressure holding time is 20 s; the drying temperature is 120°C, the heating rate is 0.5°C / min, and the holding time is 4 h. The sintering temperature is 1300°C, the heating rate is 5°C / min, and the holding time is 4 h.

[0033] (2) Preparation of ceramic binder sol: 8 parts by weight of borax is added to 25 parts by weight of aluminum sol with a solid content of 20wt%, and after sufficient dissolution, sol A is obtained; 2 parts by weight of Li2SO4 is added to 55 parts by weight of silicon sol with a solid content of 30wt%, and after sufficient dissolution, sol B is obtained; 33 parts by weight of sol A and 57 parts by weight of sol B are mixed uniformly, then 2 parts by weight of nano ZrO2 and 3 parts by weight of nano ZnO are added in turn and stirred uniformly to obtain the ceramic binder sol.

[0034] (3) Pour the ceramic binder sol prepared in step (2) into the inner hole of the grinding wheel in step (1) to immerse the inner hole of the grinding wheel in the ceramic binder, the immersion time is 30 min, and the high-speed worm grinding wheel for gear grinding is obtained after sintering, the thickness of the ceramic binder layer is 15 mm, wherein the sintering temperature is 950°C, the heating rate is 5°C / min, and the holding time is 1 h.

[0035] Example 3

[0036] A reinforcing method for a high-speed worm grinding wheel for gear grinding, the specific steps are as follows:

[0037] (1) Preparation of the worm grinding wheel: Pour the molding material into the mold with a rotation speed of 30 rpm / min, and use the abrasive tool dynamic balance molding technology to make the molding material evenly distributed in the mold, then perform press molding, and dry and sinter it to obtain the worm grinding wheel. The pressure of the press molding is 5 MPa, the pressure retention time is 20 s; the drying temperature is 120°C, the temperature rising rate is 0.5°C / min, and the holding time is 4 h. The sintering temperature is 1300°C, the temperature rising rate is 5°C / min, and the holding time is 4 h.

[0038] (2) Preparation of the ceramic bond sol: 6 parts by weight of borax is added to 35 parts by weight of aluminum sol with a solid content of 15wt%, and after being fully dissolved, sol A is obtained; 3 parts by weight of LiNO3 is added to 45 parts by weight of silicon sol with a solid content of 35wt%, and after being fully dissolved, sol B is obtained; 41 parts by weight of sol A and 48 parts by weight of sol B are mixed uniformly, and then 3 parts by weight of nano ZrO2 and 4 parts by weight of nano ZnO are added and stirred uniformly to obtain the ceramic bond sol.

[0039] (3) Pour the ceramic bond sol prepared in step (2) into the inner hole of the grinding wheel in step (1) to immerse the inner hole of the grinding wheel in the ceramic bond, the immersion time is 30 min, and after sintering, the high-speed worm grinding wheel for gear grinding is obtained, the thickness of the ceramic bond layer is 15 mm, and the sintering temperature is 1000°C, the temperature rising rate is 5°C / min, and the holding time is 1 h.

[0040] Comparative Example

[0041] (1) Preparation of the worm grinding wheel: Pour the molding material into the mold with a rotation speed of 30 rpm / min, and use the abrasive tool dynamic balance molding technology to make the molding material evenly distributed in the mold, then perform press molding, and dry and sinter it. The pressure of the press molding is 5 MPa, the pressure retention time is 20 s; the drying temperature is 120°C, the temperature rising rate is 0.5°C / min, and the holding time is 4 h. The sintering temperature is 1300°C, the temperature rising rate is 5°C / min, and the holding time is 4 h.

[0042] The static unbalance (according to the national standard GB / T 2492-2017 "Solidified Abrasive Delivered Grinding Wheel Allowable Unbalance") and the maximum linear speed (according to the national standard GB / T 2493-2013 "Rotary Test Method for Grinding Wheel") of the worm grinding wheel for gear grinding prepared in Examples 1-3 and Comparative Example are tested, and the test results are shown in the following table:

[0043]

[0044] The ceramic bond sol of the worm grinding wheel for grinding teeth in examples 1-3 is soaked and sintered, and a layer of ceramic bond can be further included around the abrasive and the periphery of the bond around the center hole of the worm grinding wheel, which can better bond the abrasive and improve the holding force of the bond on the abrasive. In addition, the addition of nano ZrO2 can not only adjust the fluidity of the ceramic bond, but also convert from tetragonal phase to monoclinic phase when stressed, utilize phase change toughening to absorb strain energy to hinder crack propagation, and through volume expansion to promote crack closure, further improve the toughness of the ceramic bond. Nano ZnO can reduce the refractoriness of the ceramic bond sol and increase its melting fluidity. Compared with the comparative example without ceramic bond impregnation reinforcement, the static unbalance grams of the worm grinding wheel in the examples decrease by 71% at the highest, and the highest linear speed can be increased by 35%.

[0045] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles of the present application, other improvements can also be made, which are considered to be within the scope of protection of the present application.

Claims

1. A method of reinforcing a high-speed worm grinding wheel for gear grinding, characterized in that, The method comprises the following steps: (1) Preparation of worm grinding wheel: pour the molding material into a rotating mold to make the molding material evenly distributed in the mold, then press into a grinding wheel blank, and dry and sinter the grinding wheel blank to obtain the worm grinding wheel; (2) Preparation of ceramic binder sol: add borax to the aluminum sol to obtain sol A; add lithium salt to the silicon sol to obtain sol B; mix sol A and sol B uniformly, then add nano-ZrO2 and nano-ZnO in sequence, and stir uniformly to obtain the ceramic binder sol, wherein the weight fractions of the raw materials are shown in the following table: (3) Pour the ceramic binder sol prepared in step (2) into the inner hole of the worm grinding wheel to immerse the inner hole of the worm grinding wheel in the ceramic binder, the immersion time is 20-40 min, and then sinter to obtain the high-speed worm grinding wheel for gear grinding.

2. The method of claim 1, wherein: The rotation rate of the mold in step (1) is 10-50 rpm / min.

3. The method of claim 1, wherein: The drying temperature of the grinding wheel blank in step (1) is 100-120℃, the heating rate is 0.1-0.5℃ / min, and the holding time is 2-4h.

4. The method of claim 1, wherein: The sintering temperature of the grinding wheel blank in step (1) is 1000-1300℃, the heating rate is 1-5℃ / min, and the holding time is 2-4h.

5. The method of claim 1, wherein: The solid content of the aluminum sol in step (2) is 15-35wt%, and the colloidal particle size is 20-80nm; the solid content of the silicon sol is 20-50wt%, and the colloidal particle size is 50-100nm.

6. The method of claim 1, wherein: The lithium salt in step (2) is one or a mixture of two or more of LiNO3, Li2CO3 and Li2SO4 in any proportion; the particle size of nano-ZrO2 is 1-100nm, and the particle size of nano-ZnO is 1-100nm.

7. The method of claim 1, wherein: The sintering temperature in step (3) is 800-1000℃, the heating rate is 1-5℃ / min, and the holding time is 1-2h.

Images