A machining process of an oil pump gear with high-precision tooth profile modification

Abstract

The application discloses a machining process of an oil pump gear with high-precision tooth direction modification; S1, uniformly mixing powder raw materials required for machining the oil pump gear; the mass percentage of the powder raw materials comprises the following components: C: 0.6-0.9, Mo: 0.01-1.0, Mn: 0.05-0.30, Cu: 1.0-4.0 and the balance of Fe; S2, pressing the raw materials into an oil pump gear rough blank A; the oil pump gear rough blank A is provided with a center hole A and an outer meshing tooth A formed after pressing, and the outer meshing tooth A is provided with a taper A at one end in the tooth direction; S3, sintering the oil pump gear rough blank A to obtain an oil pump gear rough blank B; S4, machining the inner wall of the center hole A of the rough blank B to form a taper B at two ends of the inner wall and a convex surface at the middle part; S5, shaping the oil pump gear rough blank B to shape a taper C at the other end in the tooth direction of the outer meshing tooth A, and meanwhile, the convex surface on the inner wall of the center hole A is removed, so that the oil pump gear with high-precision tooth direction modification is obtained.

Description

Technical Field

[0001] This invention relates to the field of gear processing technology, specifically to a high-precision processing technology for oil pump gears with tooth profile modification. Background Technology

[0002] Ordinary oil pump gears are usually manufactured using powder metallurgy. Powder metallurgy has advantages such as low processing cost, short processing cycle, and stable product quality. However, due to process limitations, oil pump gears manufactured by powder metallurgy can only have their tooth profile modified, and their tooth direction often cannot be modified. As a result, the operating noise of the oil pump gears will increase under high pressure or high speed conditions.

[0003] The existing process features a straight mold during molding and shaping, resulting in straight or even slanted teeth after shaping. When the gear pump operates under high pressure or high speed, the edge of the gear end face will engage, which can easily generate noise. Summary of the Invention

[0004] The purpose of this invention is to address the problem of high operating noise in oil pump gears produced by existing processes due to the inability to modify the tooth direction. This invention provides a high-precision machining process for oil pump gears with tooth direction modification. The oil pump gears machined using this invention have a tooth direction modification function, thus solving the problem of high operating noise in oil pump gears.

[0005] This invention is achieved through the following technical solution:

[0006] A high-precision machining process for a toothed oil pump gear, characterized in that the oil pump gear comprises: a gear ring body, a central hole, and external meshing teeth; the meshing surface of the external meshing teeth has a drum-shaped surface along the tooth direction.

[0007] The machining process for the oil pump gear includes the following steps:

[0008] S1. Mixing: Mix the powdered raw materials required for processing the oil pump gear evenly;

[0009] Wherein: the powder raw material comprises the following components: C: 0.6-0.9 wt%, Mo: 0.01-1.0 wt%, Mn: 0.05-0.30 wt%, Cu: 1.0-4.0 wt%, and the balance Fe;

[0010] S2, Pressing and Molding: The above-mentioned uniformly mixed raw materials are pressed into a rough blank A for the oil pump gear by a molding press;

[0011] Wherein: the oil pump gear blank A has a center hole A and an external meshing tooth A formed after pressing, and one end of the external meshing tooth A has a taper A; the press mold has a taper in the tooth direction, so that one end of the formed external meshing tooth A has a taper A in the tooth direction;

[0012] S3. Sintering: The oil pump gear blank A is sintered at high temperature to obtain oil pump gear blank B;

[0013] S4. Machining: Machining is performed on the inner wall of the center hole A in the oil pump gear blank B, forming a taper B at both ends of the inner wall of the center hole A, and forming a convex surface in the middle of the inner wall of the center hole A.

[0014] S5. Shaping: The oil pump gear blank B is shaped using a shaping mold. A taper C is shaped at the other end of the external meshing tooth A, while the taper B and convex surface on the inner wall of the center hole A are eliminated to obtain a high-precision oil pump gear with tooth profile modification.

[0015] The forming mold also has a taper in the tooth direction, so that the other end of the formed external meshing tooth A has a taper C.

[0016] Furthermore, a high-precision machining process for a toothed, profiled oil pump gear includes the following steps: Step S2, pressing and forming: Using a 30-200T CNC forming press, the uniformly mixed raw materials are pressed to form the oil pump gear blank A, and the density of the oil pump gear blank A is > 6.8 g / cm³. 3 .

[0017] Furthermore, a high-precision machining process for a toothed oil pump gear: in step S2, one end of the external meshing tooth A has a taper A of 0.002 to 0.01 mm.

[0018] Furthermore, a high-precision machining process for a toothed modified oil pump gear is as follows: S3, sintering: The oil pump gear blank A is placed in a sintering furnace and sintered at a high temperature of 1100℃~1150℃ for 10~30 minutes under a protective atmosphere to obtain the oil pump gear blank B.

[0019] Furthermore, a high-precision machining process for a toothed, profiled oil pump gear: Step S4, forming a taper B of 0.002 to 0.02 mm at both ends of the inner wall of the central hole A by machining.

[0020] Specifically, after the taper B is machined at both ends of the inner wall of the central hole A, a convex surface will naturally form in the middle of the inner wall of the central hole A.

[0021] Furthermore, a high-precision machining process for a toothed oil pump gear: the forming mold in step S5 has a non-tapered central hole mandrel, which is used to extrude and eliminate the convex surface on the inner wall of the central hole A; after forming in step S5, both ends of the external meshing tooth A have a taper of 0.002 to 0.01 mm.

[0022] Specifically, the tapers formed at both ends of the external meshing tooth A are taper A and taper C, respectively.

[0023] Furthermore, a high-precision machining process for a toothed oil pump gear: the shaping process in step S5 specifically involves: flipping the oil pump gear blank B in the opposite direction to that during pressing and forming, and then placing it in the shaping cavity of the shaping mold for shaping.

[0024] Specifically: during the shaping process, the end of the external meshing tooth A with the taper A is slightly shaped, and a shaping mold is used to shape the other end of the external meshing tooth A with a taper C that is symmetrical to the taper A; specifically, the shaping mold also has an axial taper. When the part is reversed and pressed into the mold, the original taper part of the meshing tooth A will have a small shaping allowance, while the other end will have a larger shaping allowance due to the taper of the part and the taper of the mold.

[0025] During the shaping process, the convex surface on the inner wall of the central hole A is eliminated by the extrusion of the mandrel, forming a central hole with a smooth inner wall.

[0026] Specifically, after the convex surface is eliminated by extrusion using a mandrel, the eliminated convex portion in the central hole A will form a protrusion on the meshing surface of the external meshing tooth A. At the same time, the formed protrusion is located between taper A and taper C, and finally forms a drum-shaped surface on the meshing surface, thus obtaining the external meshing tooth.

[0027] The beneficial effects of this invention are:

[0028] (1) The present invention provides a high-precision machining process for a gear with tooth profile modification. By improving the tooth profile shape during pressing and shaping, a taper is added during pressing, so that the part (gear blank A) obtained by pressing has a small taper. During shaping, the part is flipped over and pressed by a reverse taper shaping mold. The shaping allowance of the tooth is adjusted, so that the tooth profile is shaped into a drum shape of 0.002 to 0.01 mm after shaping. Thus, a gear with tooth profile modification (drum-shaped surface) is obtained. This allows the gear to contact the tooth profile first during meshing, thereby improving the gear engagement contact position and reducing the meshing noise and impact of the gear.

[0029] (2) The present invention has obtained a hydraulic pump gear with tooth profile by optimizing the processing technology. The hydraulic pump gear processed by this process has the characteristics of low meshing noise. At the same time, the processing technology of the present invention has more advantages than the hydraulic pump gear with tooth profile manufactured by post-machining. The hydraulic pump gear processed by the process of the present invention has lower meshing noise. Furthermore, the process of the present invention directly prepares the hydraulic pump gear with tooth profile, which does not require secondary tooth profile machining in the later stage. It has fewer process steps and higher production efficiency. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of a high-precision toothed modified oil pump gear obtained by the process of this invention;

[0032] Figure 2 This is a cross-sectional view of the oil pump gear blank A obtained after pressing and molding in step S2 of the process of the present invention.

[0033] Figure 3 This is a cross-sectional view of the oil pump gear blank B obtained after machining in step S4 of the process of the present invention.

[0034] Figure 4 This is a cross-sectional view of a high-precision toothed modified oil pump gear obtained by the process of this invention.

[0035] The markings in the diagram are: 1 Gear ring body, 2 Center hole, 3 External meshing tooth, 4 Center hole A, 5 External meshing tooth A, 3-1 Drum-shaped surface, 4-1 Convex surface. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] In the description of this invention, it should be understood that the terms "upper," "lower," "left," "right," "top," and "bottom," etc., indicating orientation or positional relationships, are merely for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature. Moreover, the terms "first," "second," etc., are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein.

[0038] Example 1

[0039] A high-precision machining process for a toothed oil pump gear, characterized in that the oil pump gear comprises: a gear ring body 1, a central hole 2, and external meshing teeth 3; the meshing surface of the external meshing teeth 3 has a drum-shaped surface 3-1 along the tooth direction (e.g., Figure 1 and Figure 4 (as shown);

[0040] The machining process for the oil pump gear includes the following steps:

[0041] S1. Mixing: Mix the powdered raw materials required for processing the oil pump gear evenly;

[0042] Wherein: the powder raw material comprises the following components: C: 0.7wt%, Mo: 1.0wt%, Mn: 0.1wt%, Cu: 2.0wt%, and the balance Fe;

[0043] S2. Compression Molding: The uniformly mixed raw materials are compressed using a 60T CNC molding press to form the oil pump gear blank A, wherein the density of the oil pump gear blank A is > 6.8 g / cm³. 3 ;

[0044] Wherein: the oil pump gear blank A has a center hole A4 formed after pressing and an external meshing tooth A5, and one end of the external meshing tooth A5 has a taper A of 0.002~0.01mm (e.g. Figure 2 (as shown);

[0045] S3. Sintering: The oil pump gear blank A is placed in a sintering furnace and sintered at 1120°C for 30 minutes under an ammonia decomposition protective atmosphere to obtain the oil pump gear blank B.

[0046] S4. Machining: The inner walls of the center hole A4 in the oil pump gear blank B are machined at both ends to form a taper B of 0.002-0.02mm at both ends, and a convex surface 4-1 is formed in the middle of the inner wall of the center hole A4. Figure 3 As shown;

[0047] S5. Shaping: The oil pump gear blank B is shaped using a shaping mold. A taper C of 0.002 to 0.01 mm is shaped at the other end of the external meshing tooth A5. At the same time, the taper B and the convex surface 4-1 on the inner wall of the center hole A4 are eliminated to obtain a high-precision oil pump gear with tooth profile modification.

[0048] The specific process of shaping using a shaping mold is as follows: the oil pump gear blank B is flipped to the opposite direction to that during pressing and forming, and then placed in the shaping cavity of the shaping mold for shaping.

[0049] Specifically: During the shaping process, the end of the external meshing tooth A5 with the taper A is slightly shaped. A shaping mold is used to shape the other end of the external meshing tooth A5 with a taper C symmetrical to the taper A. After shaping, both ends of the external meshing tooth A5 have a taper of 0.002–0.01 mm, i.e., taper A and taper C (e.g., ...). Figure 4 (as shown);

[0050] Simultaneously, during the shaping process, the convex surface 4-1 on the inner wall of the central hole A4 is eliminated by the extrusion of the central mandrel, ultimately forming a central hole 2 with a smooth inner wall (as shown in the image). Figure 4 (as shown);

[0051] After the convex surface 4-1 is eliminated by extrusion using a mandrel, the portion of the eliminated convex surface 4-1 in the center hole A4 will form a protrusion on the meshing surface of the external meshing gear A5. This protrusion, combined with tapers A and C, forms a drum-shaped surface 3-1, resulting in a high-precision oil pump gear with toothed profile (such as...). Figure 4 (As shown).

[0052] Example 2

[0053] A high-precision machining process for oil pump gears with tooth profile modification includes the following steps:

[0054] S1. Mixing: Mix the powdered raw materials required for processing the oil pump gear evenly;

[0055] Wherein: the powder raw material comprises the following components: C: 0.6wt%, Mo: 0.01wt%, Mn: 0.3wt%, Cu: 1.0wt%, and the balance Fe;

[0056] S2. Compression Molding: The uniformly mixed raw materials are compressed using a 60T CNC molding press to form the oil pump gear blank A, wherein the density of the oil pump gear blank A is > 6.8 g / cm³. 3 ;

[0057] Wherein: the oil pump gear blank A has a center hole A4 formed after pressing and an external meshing tooth A5, and one end of the external meshing tooth A5 has a taper A of 0.002~0.01mm (e.g. Figure 2 (as shown);

[0058] S3. Sintering: The oil pump gear blank A is placed in a sintering furnace and sintered at 1100°C for 20 minutes under an ammonia decomposition protective atmosphere to obtain the oil pump gear blank B.

[0059] S4. Machining: The inner walls of the center hole A4 in the oil pump gear blank B are machined at both ends to form a taper B of 0.002-0.02mm at both ends, and a convex surface 4-1 is formed in the middle of the inner wall of the center hole A4. Figure 3 As shown;

[0060] S5. Shaping: The oil pump gear blank B is shaped using a shaping mold. A taper C of 0.002 to 0.01 mm is shaped at the other end of the external meshing tooth A5. At the same time, the taper B and the convex surface 4-1 on the inner wall of the center hole A4 are eliminated to obtain a high-precision oil pump gear with tooth profile modification.

[0061] The difference between Example 2 and Example 1 is that the powder raw material in Example 2 includes the following components: C: 0.6wt%, Mo: 0.01wt%, Mn: 0.3wt%, Cu: 1.0wt%, and the balance Fe; the sintering temperature in Example 2 is 1100℃, and the sintering time is 20 minutes, while the other conditions are the same as in Example 1.

[0062] Example 3

[0063] The difference between Example 3 and Example 1 is that the powder raw material in Example 3 includes the following components: C: 0.9wt%, Mo: 0.85wt%, Mn: 0.05wt%, Cu: 4.0wt%, and the balance Fe; the sintering temperature in Example 3 is 1150℃, and the sintering time is 10 minutes, while the other conditions are the same as in Example 1.

[0064] The above-described preferred embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of the invention. Any obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A high-precision machining process for an oil pump gear with tooth profile modification, characterized in that, The oil pump gear includes: a gear ring body (1), a central hole (2), and external meshing teeth (3); the meshing surface of the external meshing teeth (3) has a drum-shaped surface (3-1) along the tooth direction. The machining process for the oil pump gear includes the following steps: S1. Mixing: Mix the powdered raw materials required for processing the oil pump gear evenly; The powder raw material comprises the following components: C: 0.6-0.9 wt%, Mo: 0.01-1.0 wt%, Mn: 0.05-0.30 wt%, Cu: 1.0-4.0 wt%, and the balance Fe; S2. Press molding: Use a 30-200T CNC molding press to press the above uniformly mixed raw materials to form oil pump gear blank A; The oil pump gear blank A has a central hole A (4) formed after pressing and external meshing teeth A (5). One end of the external meshing teeth A (5) has a taper A of 0.002 to 0.01 mm. The density of the oil pump gear blank A is > 6.8 g / cm³. 3 ; S3. Sintering: The oil pump gear blank A is placed in a sintering furnace and sintered at 1100℃~1150℃ for 10~30 minutes under an ammonia decomposition protective atmosphere to obtain the oil pump gear blank B. S4. Machining: Machining is performed on the inner wall of the center hole A (4) in the oil pump gear blank B, forming a taper B of 0.002 to 0.02 mm at both ends of the inner wall of the center hole A (4), and forming a convex surface (4-1) in the middle of the inner wall of the center hole A (4). S5. Shaping: The oil pump gear blank B is shaped using a shaping mold. A taper C is shaped at the other end of the tooth direction of the external meshing tooth A (5). At the same time, the taper B and the convex surface (4-1) on the inner wall of the center hole A (4) are eliminated to obtain a high-precision oil pump gear with tooth direction modification.

2. The machining process for a high-precision oil pump gear with tooth profile modification according to claim 1, characterized in that, The forming mold in step S5 has a non-tapered central hole mandrel, which is used to extrude and eliminate the convex surface (4-1) on the inner wall of the central hole A (4); after the forming in step S5, both ends of the external meshing tooth A (5) have a taper of 0.002 to 0.01 mm.

3. The machining process for a high-precision oil pump gear with tooth profile modification according to claim 2, characterized in that, The shaping process in step S5 is as follows: the oil pump gear blank B is flipped to the opposite direction to that during pressing and forming, and then placed in the shaping cavity of the shaping mold for shaping. In the process of shaping, the end of the external meshing tooth A (5) with the taper A is slightly shaped, and the other end of the external meshing tooth A (5) is shaped with a taper C that is symmetrical to the taper A using a shaping mold; During the shaping process, the convex surface (4-1) on the inner wall of the central hole A (4) is eliminated by the extrusion of the mandrel, forming a central hole (2) with a smooth inner wall.

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