阅读说明：本技术 一种汽车自动变速箱拨毂换挡齿轮及其制备方法 (Hub shifting gear of automatic transmission of automobile and preparation method thereof ) 是由 施昌旭 夏敏 刘桦 张艳伟 石小荣 于 2020-11-26 设计创作，主要内容包括：本发明公开一种汽车自动变速箱拨毂换挡齿轮及其制备方法。包括齿轮本体和外齿；齿轮本体的中部设置有压轴中心孔；外齿设置在齿轮本体的外圆周面上；齿轮本体的一侧成一体化设置有定位套,定位套上设置有第一凹槽；齿轮本体的另一侧依次设置有第二凹槽和第三凹槽；齿轮本体上还设置有连接孔和减重孔。制备：采用粉末冶金方法制备,包括如下过程：按照换挡齿轮的合金成分进行配料并混合→压制成型→烧结硬化→回火→检验包装入库。本发明的汽车自动变速箱拨毂换挡齿轮降低了拨毂总成装配难度、提高了组装效率、降低组件成本,利于汽车轻量化；本发明采用的粉末冶金制备方法,成本低,生产的齿轮满足自动变速箱拨毂换挡齿轮高精度、高品质的要求。(The invention discloses a hub shifting gear of an automatic gearbox of an automobile and a preparation method thereof. Comprises a gear body and external teeth; the middle part of the gear body is provided with a central hole of the pressing shaft; the outer teeth are arranged on the outer circumferential surface of the gear body; one side of the gear body is integrally provided with a positioning sleeve, and a first groove is formed in the positioning sleeve; a second groove and a third groove are sequentially formed in the other side of the gear body; the gear body is also provided with a connecting hole and a lightening hole. Preparation: the preparation method adopts a powder metallurgy method and comprises the following steps: mixing the materials according to the alloy components of the gear shifting wheel → pressing and forming → sintering and hardening → tempering → inspecting and packaging. The hub shifting gear of the automatic gearbox of the automobile reduces the assembly difficulty of the hub shifting assembly, improves the assembly efficiency, reduces the component cost and is beneficial to the light weight of the automobile; the powder metallurgy preparation method adopted by the invention has low cost, and the produced gear meets the requirements of high precision and high quality of the hub shifting gear of the automatic gearbox.)

1. A hub shifting gear of an automatic gearbox of an automobile is characterized by comprising a gear body (1) and external teeth (2); a central hole (3) of a pressing shaft is formed in the middle of the gear body (1); the external teeth (2) are arranged on the outer peripheral surface of the gear body (1); a positioning sleeve (4) is arranged on one side of the gear body (1), the positioning sleeve (4) and the gear body (1) are integrally arranged, and a first groove (5) is formed in the positioning sleeve (4); a second groove (6) and a third groove (7) for assembly are sequentially formed in the other side of the gear body (1), and the second groove (6) is communicated with the third groove (7); the gear body (1) is further provided with a plurality of connecting holes (8) and a plurality of lightening holes (9) for lightening the whole weight of the gear shifting gear.

2. The automotive automatic transmission hub shifting gear according to claim 1, characterized in that the number of the lightening holes (9) is 6 and the lightening holes are evenly distributed on the gear body (1).

3. The automotive automatic transmission hub shifting gear according to claim 2, characterized in that the lightening holes (9) are kidney-shaped holes.

4. The hub shifting gear of an automatic gearbox of an automobile according to claim 1, characterized in that the number of the connecting holes (8) is 3, and the connecting holes are uniformly distributed on the gear body (1).

5. The method for preparing the hub shifting gear of the automatic gearbox of the automobile according to any one of claims 1 to 4, wherein the hub shifting gear is prepared by a powder metallurgy method and comprises the following steps:

(1) mixing the materials according to the alloy components of the gear shifting gear: uniformly mixing powder metallurgy materials required by a hub shifting gear of an automatic gearbox of an automobile in a mixer, wherein the powder metallurgy materials comprise the following components in percentage by mass; c: 0.63-0.77%, Mo: 0.75-0.90%, Cr: 0-2.2%, Ni: 1.35-1.65%, Cu: 0.9-1.10%, Mn: 0-1.5%, Si: 0-1.5%, Ti: 0 to 1.5 percent; the balance of Fe and inevitable impurities;

(2) pressing and forming: putting the prepared powder metallurgy material into a die of a CNC (computerized numerical control) forming press to be pressed to obtain a formed gear shifting gear green body;

(3) sintering and hardening: placing the formed gear shifting gear green body into a sintering furnace, sintering in an oxygen-free environment, and then air-cooling and quenching to obtain a sintering hardened gear; gear hardness HRA 70-73, tooth profile shape deviation Ffa 0.002.002-0.003, tooth profile inclination deviation Fha 0.004-0.006, tooth direction shape deviation Ffb 0.003-0.004, tooth direction inclination deviation Fhb 0.013-0.015, tooth pitch cumulative total deviation Fp 0.018-0.019, and radial run-out deviation Fr 0.023-0.025;

(4) tempering: tempering the sintered and hardened gear, and recovering stress to obtain the hub shifting gear of the automatic gearbox of the automobile;

(5) and (3) inspecting and packaging: and inspecting, packaging and warehousing the hub shifting gear of the automatic gearbox of the automobile obtained after tempering.

6. The method for preparing the hub shifting gear of the automatic gearbox of the automobile according to the claim 5, wherein the powder metallurgy material in the step (1) comprises the following components in percentage by mass; c: 0.63-0.77%, Mo: 0.75-0.90%, Cr: 1.1-2.2%, Ni: 1.35-1.65%, Cu: 0.9-1.10%, Mn: 0.5-1.5%, Si: 0.9-1.5%, Ti: 0.85 to 1.5 percent; the balance being Fe and unavoidable impurities.

7. The method for preparing the hub shifting gear of the automatic gearbox of the automobile according to the claim 5, wherein the step (2) is carried out by pressing: placing the prepared powder metallurgy material into a die of a CNC forming press with 200 and 1000 tons for pressing to obtain a formed gear shifting gear green body; the tooth forming density is more than or equal to 7.0g/cm³The integral forming density is more than or equal to 6.9g/cm³The dividing density of each forming section is less than or equal to 0.2g/cm³。

8. The method for preparing the hub shifting gear of the automatic gearbox of the automobile according to the claim 5, wherein the step (3) is sintering and hardening: placing the formed gear shifting gear green body into a mesh belt type sintering furnace, and sintering for 30-45 minutes in a mixed atmosphere of hydrogen and nitrogen, wherein the sintering temperature is 1110-1130 ℃; and after sintering, cooling and quenching by taking nitrogen as a cooling medium to obtain the sinter-hardened gear.

9. The method for preparing the hub shifting gear of the automatic gearbox of the automobile according to claim 8, wherein the volume ratio of the hydrogen to the nitrogen is 1: 9; the cooling rate is 2.5-5 deg.C/sec.

10. The method for preparing the hub shifting gear of the automatic gearbox of the automobile according to the claim 5, wherein the step (4) tempering: and tempering the sintered and hardened gear in air at the temperature of 180-300 ℃ for 30-60 minutes, and recovering the stress to obtain the hub shifting gear of the automatic gearbox of the automobile.

Technical Field

The invention relates to the field of processing of automobile automatic transmission parts, in particular to a hub shifting gear of an automobile automatic transmission and a powder metallurgy preparation method thereof.

Background

The hub shifting gear of the automatic gearbox of the automobile needs to have the characteristics of high precision and high mechanical property. Meanwhile, along with the requirements of energy conservation and consumption reduction, automobiles are developing towards light weight. The traditional gearbox hub shifting gear is machined by a steel part and is assembled with a positioning guide sleeve of a die casting in a matching mode. Two parts machining cost height, product weight are heavy, are unfavorable for car lightweight, and the gear precision is low.

Disclosure of Invention

The invention aims to provide a hub shifting gear of an automatic gearbox of an automobile, and the hub shifting gear is characterized in that a gear body and a positioning sleeve are integrally arranged, a die casting positioning sleeve is omitted in assembly, the assembly difficulty of a hub shifting assembly is reduced, the assembly efficiency is improved, the assembly cost is reduced, and lightening holes are formed in the gear body on the premise of not influencing the compressive strength of the gear, so that the weight of the shifting gear is greatly reduced on the original basis, and the light weight of the automobile is facilitated; the invention also aims to provide a powder metallurgy preparation method of the hub shifting gear of the automatic gearbox of the automobile, wherein a powder metallurgy matrix has the characteristics of pores and self-lubrication, the reduction of the working noise of the shifting gear is facilitated, the performance of the gearbox is improved, and the hub shifting gear is produced by adopting a proper raw material formula and a sintering hardening method, so that the product has high strength and small deformation, and meets the use requirements of high precision and high strength.

The invention is realized by the following technical scheme:

a hub shifting gear of an automatic gearbox of an automobile is characterized by comprising a gear body and external teeth; a central hole of the pressing shaft is formed in the middle of the gear body; the outer teeth are arranged on the outer circumferential surface of the gear body; a positioning sleeve is arranged on one side of the gear body, the positioning sleeve and the gear body are integrally arranged, and a first groove is formed in the positioning sleeve; a second groove and a third groove for assembling the gear shifting gear are sequentially formed in the other side of the gear body, and the second groove is communicated with the third groove; the gear body is further provided with a plurality of connecting holes and a plurality of lightening holes for lightening the whole weight of the gear shifting gear. Specifically, the gear body and the positioning sleeve are integrally arranged, the die casting positioning sleeve is omitted in assembly, the assembly difficulty of the hub shifting assembly is reduced, the assembly efficiency is improved, the assembly cost is reduced, and the lightening holes are formed in the gear body on the premise that the compressive strength of the gear is not influenced, so that the weight of the gear shifting gear is greatly reduced on the original basis, and the light weight of an automobile is facilitated. Compared with the traditional steel part machining gear shifting gear and casting positioning sleeve combined assembly, the gear shifting gear and the positioning sleeve are designed into an integrated part, so that the number of parts is reduced, the assembly efficiency is improved, the product cost is reduced, and the precision and the performance of an assembly are improved.

Further, the number of the weight-reducing holes is 6, and the weight-reducing holes are evenly distributed on the gear body. Specifically, the 6 lightening holes are divided into 3 groups in pairs, and the lightening holes in each group are arranged on the gear body at equal intervals. The lightening holes are uniformly distributed on the gear body, so that the whole weight of the hub shifting gear of the automatic gearbox of the automobile is uniform, and the hub shifting gear of the automatic gearbox of the automobile is convenient to position stably during installation.

Furthermore, the lightening holes are kidney-shaped holes.

Furthermore, the number of the connecting holes is 3, and the connecting holes are uniformly distributed on the gear body. Specifically, the 3 connecting holes are respectively arranged between two adjacent groups of lightening holes; the connecting holes are round bolt holes, when the hub shifting gear of the automatic gearbox of the automobile is assembled, the connecting holes can be used for fixedly connecting the shifting gear through the connecting bolts, and 3 connecting holes are uniformly formed, so that the stress is more uniform.

A preparation method of a hub shifting gear of an automatic gearbox of an automobile is characterized by adopting a powder metallurgy method, and comprises the following steps:

(1) mixing the materials according to the alloy components of the gear shifting gear: uniformly mixing powder metallurgy materials required by a hub shifting gear of an automatic gearbox of an automobile in a mixer, wherein the powder metallurgy materials comprise the following components in percentage by mass; c: 0.63-0.77%, Mo: 0.75-0.90%, Cr: 0-2.2%, Ni: 1.35-1.65%, Cu: 0.9-1.10%, Mn: 0-1.5%, Si: 0-1.5%, Ti: 0 to 1.5 percent; the balance of Fe and inevitable impurities;

(2) pressing and forming: putting the prepared powder metallurgy material into a die of a CNC (computerized numerical control) forming press to be pressed to obtain a formed gear shifting gear green body; the joint of each part of the green body has no crack, and burrs are automatically brushed after the green body is demoulded;

(3) sintering and hardening: placing the formed gear shifting gear green body into a sintering furnace, sintering in an oxygen-free environment, and then air-cooling and quenching to obtain a sintering hardened gear; gear hardness HRA 70-73, tooth profile shape deviation Ffa 0.002.002-0.003, tooth profile inclination deviation Fha 0.004-0.006, tooth direction shape deviation Ffb 0.003-0.004, tooth direction inclination deviation Fhb 0.013-0.015, tooth pitch cumulative total deviation Fp 0.018-0.019, and radial run-out deviation Fr 0.023-0.025; the subsequent local high-frequency quenching is avoided by adopting a sintering hardening process to improve the hardness and the strength;

(4) tempering: tempering the sintered and hardened gear, and recovering stress to obtain the hub shifting gear of the automatic gearbox of the automobile;

(5) and (3) inspecting and packaging: and inspecting, packaging and warehousing the hub shifting gear of the automatic gearbox of the automobile obtained after tempering. The powder metallurgy preparation method for the hub shifting gear of the automatic gearbox of the automobile creatively adopts a proper powder metallurgy material and produces the hub shifting gear of the automatic gearbox of the powder metallurgy with high precision, high strength and low cost through a sintering hardening process; the sinter hardening is one-step production operation, can meet the mechanical property requirement of the product without subsequent high-frequency quenching or heat treatment, reduces heat treatment deformation, and is a process with great cost benefit; and the produced gear shifting gear meets the use requirements of high hardness and high precision of the hub of the automatic gearbox. The invention is manufactured by adopting a powder metallurgy method, effectively solves the production difficulties of high production cost, low tooth profile precision, high assembly noise, high bad proportion and the like of the traditional processing method, and fundamentally meets the requirements of high precision and high quality of the hub shifting gear of the automatic gearbox.

Further, the powder metallurgy material in the step (1) comprises the following components in percentage by mass; c: 0.63-0.77%, Mo: 0.75-0.90%, Cr: 1.1-2.2%, Ni: 1.35-1.65%, Cu: 0.9-1.10%, Mn: 0.5-1.5%, Si: 0.9-1.5%, Ti: 0.85 to 1.5 percent; the balance being Fe and unavoidable impurities.

Further, the step (2) is to press and form: placing the prepared powder metallurgy material into a die of a CNC forming press with 200 and 1000 tons for pressing to obtain a formed gear shifting gear green body; the tooth forming density is more than or equal to 7.0g/cm³The integral forming density is more than or equal to 6.9g/cm³The dividing density of each forming section is less than or equal to 0.2g/cm³. Preferably, the prepared powder metallurgy material is put into a die of a CNC forming press with 300-500 tons for pressing and forming.

Further, step (3) sinter hardening: placing the formed gear shifting gear green body into a mesh belt type sintering furnace, and sintering for 30-45 minutes in a mixed atmosphere of hydrogen and nitrogen, wherein the sintering temperature is 1110-1130 ℃; and after sintering, cooling and quenching by taking nitrogen as a cooling medium to obtain the sinter-hardened gear.

Further, the volume ratio of the hydrogen gas to the nitrogen gas is 1: 9; the cooling rate is 2.5-5 deg.C/sec.

Further, tempering in the step (4): and tempering the sintered and hardened gear in air at the temperature of 180-300 ℃ for 30-60 minutes, and recovering the stress to obtain the hub shifting gear of the automatic gearbox of the automobile.

The invention has the beneficial effects that:

(1) according to the hub shifting gear of the automatic gearbox of the automobile, the gear body and the positioning sleeve are formed by the integrated piece, so that the assembly difficulty of the hub shifting assembly is reduced, the assembly efficiency is improved, the assembly cost is reduced, and on the premise of not influencing the compressive strength of the gear, 6 waist-shaped lightening holes are formed in the gear body, so that the weight of the shifting gear is reduced by about 30% on the original basis, and the requirement of light weight of the automobile is met; compared with the traditional steel part machining gear shifting gear and casting positioning sleeve combined assembly, the gear shifting gear and the positioning sleeve are designed into an integrated part, so that the number of parts is reduced, the assembly efficiency is improved, the product cost is reduced, and the precision and the performance of an assembly are improved.

(2) The powder metallurgy preparation method effectively solves the production difficulties of high production cost, low tooth profile precision, high assembly noise, high poor proportion and the like of the traditional processing method, and fundamentally meets the requirements of high precision and high quality of the hub shifting gear of the automatic gearbox; the powder metallurgy substrate has the pore characteristics, has the functions of noise absorption and self-lubrication, and can reduce noise and prolong the service life of the gear by self-lubrication.

(3) According to the invention, through a special raw material formula and a sintering hardening process, the product has strong mechanical property and small deformation, and the gear has high hardness and high precision and meets the use requirement; the hardness HRA of the gear shifting gear is 70-73, the deviation of the tooth profile shape is Ffa 0.002.002-0.003, the deviation of the tooth profile inclination is Fha 0.004-0.006, the deviation of the tooth direction shape is Ffb 0.003-0.004, the deviation of the tooth direction inclination is Fhb 0.013-0.015, the cumulative total deviation of the tooth pitch Fp is 0.018-0.019, and the radial run-out deviation Fr is 0.023-0.025.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a front view of a hub shifting gear of an automatic transmission of an automobile of the present invention;

FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;

FIG. 3 is an external view of the hub shifting gear of the automatic transmission of the automobile.

In the figure: the gear comprises a gear body 1, outer teeth 2, a shaft pressing central hole 3, a positioning sleeve 4, a first groove 5, a second groove 6, a third groove 7, a connecting hole 8 and a lightening hole 9.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

As shown in fig. 1-3, a hub shifting gear of an automatic transmission of an automobile comprises a gear body 1 and external teeth 2; the middle part of the gear body 1 is provided with a pressing shaft center hole 3; the external teeth 2 are arranged on the outer circumferential surface of the gear body 1; a positioning sleeve 4 is arranged on one side of the gear body 1, the positioning sleeve 4 and the gear body 1 are formed by an integral piece, and a first groove 5 is formed in the positioning sleeve 4; a second groove 6 and a third groove 7 for assembling the hub shifting gear of the automatic gearbox of the automobile are sequentially arranged on the other side of the gear body 1, and the second groove 6 is communicated with the third groove 7; the gear body 1 is further provided with a connecting hole 8 (when the hub shifting gear of the automatic gearbox of the automobile is assembled, the connecting hole 8 can be connected with a bolt for fixing the shifting gear) and a lightening hole 9 for lightening the whole weight of the shifting gear. Preferably, there are 6 weight-reducing holes 9 uniformly distributed on the gear body 1 (the weight-reducing holes 9 are uniformly distributed on the gear body 1, so that the overall weight of the hub shifting gear of the automatic transmission of the automobile is uniform, and the position stability during installation of the hub shifting gear of the automatic transmission of the automobile is facilitated), and the weight-reducing holes 9 are kidney-shaped holes; the connecting holes 8 are provided with 3 and are uniformly distributed on the gear body 1. According to the hub shifting gear of the automatic gearbox of the automobile, the gear body 1 and the positioning sleeve 4 are formed by an integrated piece, so that the assembly difficulty of the hub shifting assembly is reduced, the assembly efficiency is improved, the component cost is reduced, and the precision and the performance of the assembly are improved; on the premise of not influencing the compressive strength of the gear, the gear body 1 is provided with 6 waist-shaped lightening holes 9, so that the weight of the gear to be shifted is reduced by about 30 percent on the original basis, and the light weight of an automobile is facilitated.

Example 2

A method for preparing a hub shifting gear of an automatic gearbox of an automobile adopts a powder metallurgy method, and specifically comprises the following steps:

(1) mixing the materials according to the alloy components of the gear shifting gear: powder metallurgy materials required by the hub shifting gear of the automatic gearbox of the automobile are uniformly mixed in a mixer, wherein the powder metallurgy materials comprise the following components in percentage by mass; c: 0.63%, Mo: 0.75%, Cr: 2.2%, Ni: 1.35%, Cu: 0.9%, Mn: 1.5%, Si: 1.5%, Ti: 1.5 percent; the balance of Fe and inevitable impurities;

(2) pressing and forming: putting the prepared powder metallurgy material into a die of a 650-ton CNC (computerized numerical control) forming press for pressing to obtain a formed gear shifting gear green body; the tooth forming density is 7.1g/cm³The bulk molding density was 6.95g/cm³Each forming section is dividedThe density is less than or equal to 0.2g/cm³(ii) a The joint of each part of the green body has no crack, and burrs are automatically brushed after the green body is demoulded;

(3) sintering and hardening: placing the formed gear shifting gear green body into a mesh belt type sintering furnace, and sintering for 30 minutes in a mixed atmosphere of hydrogen and nitrogen (wherein H₂And N₂Is 1: 9) the sintering temperature is 1120 ℃; after sintering, cooling and quenching (the cooling speed is 4 ℃/s) by taking nitrogen as a cooling medium to obtain a sintering and hardening gear;

(4) tempering: tempering the sintered and hardened gear for 60 minutes at 180 ℃ in the air to recover the stress, thus obtaining the hub shifting gear of the automatic gearbox of the automobile;

(5) and (3) inspecting and packaging: and inspecting, packaging and warehousing the hub shifting gear of the automatic gearbox of the automobile obtained after tempering.

The main indexes of the qualified product are as follows:

the standard requires that: the gear hardness HRA is more than or equal to 65, the tooth profile shape deviation Ffa is less than or equal to 0.009, the tooth profile inclination deviation Fha is less than or equal to 0.022, the tooth direction shape deviation Ffb is less than or equal to 0.009, the tooth direction inclination deviation Fhb is less than or equal to 0.036, the cumulative total tooth pitch deviation Fp is less than or equal to 0.11, and the radial run-out deviation Fr is less than or equal to 0.08.

The data of the hub shifting gear of the automatic gearbox of the automobile manufactured in the embodiment 2 is tested, and the data are as follows: the gear hardness HRA 73, the tooth profile shape deviation Ffa0.002, the tooth profile inclination deviation Fha0.005, the tooth direction shape deviation Ffb0.004, the tooth direction inclination deviation Fhb0.015, the tooth pitch cumulative total deviation Fp0.018 and the radial run-out deviation Fr0.023; therefore, the actually measured values of the hub shifting gear of the automatic gearbox of the automobile manufactured by the powder metallurgy method all meet the standard requirements.

Example 3

A method for preparing a hub shifting gear of an automatic gearbox of an automobile adopts a powder metallurgy method, and specifically comprises the following steps:

(1) mixing the materials according to the alloy components of the gear shifting gear: powder metallurgy materials required by the hub shifting gear of the automatic gearbox of the automobile are uniformly mixed in a mixer, wherein the powder metallurgy materials comprise the following components in percentage by mass; c: 0.77%, Mo: 0.9%, Cr: 2.0%, Ni: 1.65%, Cu: 1.1%, Mn: 0.5%, Si: 1.0%, Ti: 1.0 percent; the balance of Fe and inevitable impurities;

(2) pressing and forming: putting the prepared powder metallurgy material into a die of a CNC (computerized numerical control) forming press for pressing to obtain a formed gear shifting gear green body; the tooth forming density is 7.05g/cm³The bulk molding density was 6.92g/cm³The dividing density of each forming section is less than or equal to 0.2g/cm³(ii) a The joint of each part of the green body has no crack, and burrs are automatically brushed after the green body is demoulded;

(3) sintering and hardening: placing the formed gear shifting gear green body into a mesh belt type sintering furnace, and sintering for 45 minutes in a mixed atmosphere of hydrogen and nitrogen (wherein H is₂And N₂Is 1: 9) the sintering temperature is 1125 ℃; after sintering, cooling and quenching (the cooling speed is 5 ℃/s) by taking nitrogen as a cooling medium to obtain a sintering and hardening gear;

(4) tempering: tempering the sintered and hardened gear for 45 minutes at 300 ℃ in the air to recover the stress, thus obtaining the hub shifting gear of the automatic gearbox of the automobile;

(5) and (3) inspecting and packaging: and inspecting, packaging and warehousing the hub shifting gear of the automatic gearbox of the automobile obtained after tempering.

The main indexes of the qualified product are as follows:

the standard requires that: the gear hardness HRA is more than or equal to 65, the tooth profile shape deviation Ffa is less than or equal to 0.009, the tooth profile inclination deviation Fha is less than or equal to 0.022, the tooth direction shape deviation Ffb is less than or equal to 0.009, the tooth direction inclination deviation Fhb is less than or equal to 0.036, the cumulative total tooth pitch deviation Fp is less than or equal to 0.11, and the radial run-out deviation Fr is less than or equal to 0.08.

The data of the hub shifting gear of the automatic gearbox of the automobile manufactured by the embodiment 3 is tested, and the data are as follows: gear hardness HRA 71, tooth profile shape deviation Ffa0.003, tooth profile inclination deviation Fha0.004, tooth direction shape deviation Ffb0.003, tooth direction inclination deviation Fhb0.013, tooth pitch cumulative total deviation Fp0.019 and radial run-out deviation Fr0.025; therefore, the actually measured values of the hub shifting gear of the automatic gearbox of the automobile manufactured by the powder metallurgy method all meet the standard requirements.

Example 4

A method for preparing a hub shifting gear of an automatic gearbox of an automobile adopts a powder metallurgy method, and specifically comprises the following steps:

(1) mixing the materials according to the alloy components of the gear shifting gear: powder metallurgy materials required by the hub shifting gear of the automatic gearbox of the automobile are uniformly mixed in a mixer, wherein the powder metallurgy materials comprise the following components in percentage by mass; c: 0.69%, Mo: 0.83%, Cr: 1.1%, Ni: 1.55%, Cu: 1.05%, Mn: 1.2%, Si: 0.9%, Ti: 0.85 percent; the balance of Fe and inevitable impurities;

(2) pressing and forming: placing the prepared powder metallurgy material into a die of a 1000-ton CNC (computerized numerical control) forming press for pressing to obtain a formed gear shifting gear green body; the tooth forming density is 7.12g/cm³The bulk molding density was 6.97g/cm³The dividing density of each forming section is less than or equal to 0.2g/cm³(ii) a The joint of each part of the green body has no crack, and burrs are automatically brushed after the green body is demoulded;

(3) sintering and hardening: placing the formed gear shifting gear green body into a mesh belt type sintering furnace, and sintering for 60 minutes in a mixed atmosphere of hydrogen and nitrogen (wherein H is₂And N₂Is 1: 9) the sintering temperature is 1115 ℃; after sintering, cooling and quenching are carried out by taking nitrogen as a cooling medium (the cooling speed is 3 ℃/s) to obtain a sintering and hardening gear;

(4) tempering: tempering the sintered and hardened gear in the air at 260 ℃ for 30 minutes to recover the stress, thus obtaining the hub shifting gear of the automatic gearbox of the automobile;

(5) and (3) inspecting and packaging: and inspecting, packaging and warehousing the hub shifting gear of the automatic gearbox of the automobile obtained after tempering.

The main indexes of the qualified product are as follows:

the standard requires that: the gear hardness HRA is more than or equal to 65, the tooth profile shape deviation Ffa is less than or equal to 0.009, the tooth profile inclination deviation Fha is less than or equal to 0.022, the tooth direction shape deviation Ffb is less than or equal to 0.009, the tooth direction inclination deviation Fhb is less than or equal to 0.036, the cumulative total tooth pitch deviation Fp is less than or equal to 0.11, and the radial run-out deviation Fr is less than or equal to 0.08.

The data of the hub shifting gear of the automatic transmission prepared in the embodiment 4 is tested, and the data are as follows: the gear hardness HRA 70, the tooth profile shape deviation Ffa0.002, the tooth profile inclination deviation Fha0.006, the tooth direction shape deviation Ffb0.004, the tooth direction inclination deviation Fhb0.015, the tooth pitch cumulative total deviation Fp0.018 and the radial run-out deviation Fr0.023; therefore, the actually measured values of the hub shifting gear of the automatic gearbox of the automobile manufactured by the powder metallurgy method all meet the standard requirements.

The above-mentioned preferred embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention. Obvious variations or modifications of the present invention are within the scope of the present invention.