A method of tooth shaping by milling

Abstract

The application discloses a tooth direction modification milling method, comprising the following steps: tooth blank forging; tooth blank rough machining; tooth blank milling; carburizing and quenching; reference finishing; gear grinding processing to obtain a finished gear; wherein the tooth blank milling comprises the following steps: obtaining a gear helix angle and tooth width, a first tooth surface modification direction depth and a second tooth surface modification direction depth of a tooth; calculating a first tooth surface modification direction helix angle and a second tooth surface modification direction helix angle according to the gear helix angle, the tooth width, the first tooth surface modification direction depth and the second tooth surface modification direction depth; milling the first tooth surface of the tooth according to the first tooth surface modification direction helix angle and reserving a target allowance; and milling the second tooth surface of the tooth according to the second tooth surface modification direction helix angle. The milling method provided by the application is characterized in that, after gear grinding, the hardened layer depth of each section of the tooth is consistent, the tooth root transition curve appearance is consistent, and finally the tooth surface bearing capacity and the tooth root bending strength of the tooth are consistent.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of gear machining method, in particular to a kind of gear milling method of tooth modification. BACKGROUND

[0002] The development trend of gear machining in mechanical industry is higher and higher precision, higher and higher power density, more and more complex structure, for example: with complex edge modification and modification, while realizing low stiffness and high strength, realizing the requirement of high power density.

[0003] High-precision gear parts are generally rough-machined by gear hobbing or gear milling, and finally meet the design structure requirements by gear grinding, however, excessive edge modification and modification, especially modification, will bring various adverse consequences to gear grinding process after carburizing and quenching; first, the price of gear grinding time is increased, and the manufacturing cost is greatly improved; second, the uneven grinding allowance on each section of the tooth will affect the hardened depth of the finished product after carburizing and quenching, causing the difference in load capacity of each section; third, the difference in grinding allowance of each section will form different tooth root effects on the tooth root transition curve part, some sections normally transition, some sections form bosses, affecting the tooth root bending strength and increasing the risk of tooth breakage.

[0004] The prior art generally uses the working method of radial deepening of the milling cutter to process left-right symmetrical modification, however, the method in the prior art can only process left-right modification symmetrical tooth, and the tooth root circle processed by the existing method has non-uniform diameter, resulting in uneven strength of each tooth on the gear and poor use effect.

[0005] Therefore, how to effectively improve the consistency of the load capacity and performance of the gear is a technical problem to be solved by those skilled in the art at present. SUMMARY

[0006] The purpose of the present application is to provide a gear milling method for tooth modification, which is used to improve the consistency of tooth surface load capacity and tooth root bending strength of the tooth.

[0007] To achieve the above purpose, the present application provides the following technical scheme:

[0008] A gear milling method for tooth modification is used to process the tooth of a gear, and the left and right sides of the tooth are respectively a first tooth surface and a second tooth surface; the method comprises the following steps:

[0009] blank forging, rough machining of the blank, gear milling of the blank, carburizing and quenching, precision machining reference, gear grinding processing, and obtaining a finished gear;

[0010] The step of gear milling of the blank comprises:

[0011] obtaining a helix angle of the gear and tooth width, first tooth surface modification depth and second tooth surface modification depth of the tooth;

[0012] calculating a first tooth surface modification helix angle and a second tooth surface modification helix angle according to the helix angle of the gear, the tooth width, the first tooth surface modification depth and the second tooth surface modification depth;

[0013] milling the first tooth surface of the tooth according to the first tooth surface modification helix angle and leaving a target allowance;

[0014] milling the second tooth surface of the tooth according to the second tooth surface modification helix angle.

[0015] Preferably, the step of milling the second tooth surface of the tooth according to the second tooth surface modification helix angle further comprises:

[0016] obtaining a pitch circle diameter of the gear;

[0017] calculating a target angle according to the pitch circle diameter, the first tooth surface modification depth and the second tooth surface modification depth;

[0018] rotating the gear by the target angle.

[0019] Preferably, the step of rotating the gear by the target angle comprises rotating a worktable carrying the gear by the target angle.

[0020] Preferably, the target angle α is calculated according to formula (1):

[0021]

[0022] wherein K is the pitch circle diameter, c is the first tooth surface modification depth, and e is the second tooth surface modification depth.

[0023] Preferably, the target allowance M=(c+e) / 2+(0.8-1.2)mm, wherein c is the first tooth surface modification depth and e is the second tooth surface modification depth.

[0024] Preferably, the first tooth surface modification depth and the second tooth surface modification depth are different in value.

[0025] Preferably, the first tooth surface modification helix angle β1 is calculated according to formula (2):

[0026]

[0027] wherein b is the tooth width, c is the first tooth surface modification depth, β is the helix angle of the gear, and n=1.

[0028] Preferably, the second tooth surface modification helix angle β2 is calculated according to formula (3):

[0029]

[0030] Wherein: b is the tooth width, e is the second tooth surface modification depth, β is the gear helix angle, n = 2.

[0031] The tooth modification milling method provided by the application is used for processing gear teeth, and the left and right sides of the gear teeth are respectively a first tooth surface and a second tooth surface. The method comprises the following steps: forging a tooth blank; rough machining the tooth blank; milling the tooth blank; carburizing and quenching; processing a reference; grinding processing to obtain a finished gear; wherein the step of milling the tooth blank comprises the following steps: obtaining a gear helix angle and tooth width, first tooth surface modification depth and second tooth surface modification depth of the gear teeth; calculating a first tooth surface modification helix angle and a second tooth surface modification helix angle according to the gear helix angle, the tooth width, the first tooth surface modification depth and the second tooth surface modification depth; milling the first tooth surface of the gear teeth according to the first tooth surface modification helix angle and reserving a target allowance; and milling the second tooth surface of the gear teeth according to the second tooth surface modification helix angle. The tooth modification milling method provided by the application uses the data of the gear helix angle, the tooth width, the first tooth surface modification depth and the second tooth surface modification depth to respectively calculate the first tooth surface modification helix angle of the first tooth surface and the second tooth surface modification helix angle of the second tooth surface, so that the same grinding allowance and the same root digging amount are pre-processed in the rough machining stage of the tooth blank milling, thereby ensuring that the upper, middle and lower different sections of the gear teeth have basically the same grinding allowance after the carburizing and quenching process, and ensuring that the hardening layer depth of each section of the gear teeth is consistent and the tooth root transition curve appearance is consistent after the gear teeth are ground, so that the tooth surface bearing capacity and the tooth root bending strength of the gear teeth are consistent.

[0032] In a preferred embodiment, the first tooth surface modification depth and the second tooth surface modification depth have different values. That is, this method is mainly used for processing gear teeth with asymmetric first tooth surfaces and second tooth surfaces, and the first tooth surface modification depth and the second tooth surface modification depth are calculated respectively by regarding the large modification gear as having different helix angles of the first tooth surface and the second tooth surface, and the first tooth surface and the second tooth surface are processed respectively, so as to ensure the consistency of the grinding allowance and the consistency of the performance. BRIEF DESCRIPTION OF DRAWINGS

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. 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.

[0034] Figure 1 A flowchart illustrating a specific embodiment of the milling method for tooth profile modification provided by the present invention;

[0035] Figure 2 for Figure 1 A flowchart of a specific implementation of the gear blank milling step in the gear milling method shown;

[0036] Figure 3 A cross-sectional view of a gear machined using the tooth profile milling method provided by this invention;

[0037] Figure 4 A cross-sectional view of the gear teeth processed by the tooth profile milling method provided by the present invention;

[0038] Wherein: 1-gear; 2-tooth; 21-first tooth surface; 22-second tooth surface. Detailed Implementation

[0039] The core of this invention is to provide a milling method for tooth profile modification, which can significantly improve the consistency of gear tooth performance and ensure stable and reliable performance.

[0040] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] Please refer to Figures 1 to 4 , Figure 1 A flowchart illustrating a specific embodiment of the milling method for tooth profile modification provided by the present invention; Figure 2 for Figure 1 A flowchart of a specific implementation of the gear blank milling step in the gear milling method shown; Figure 3 A cross-sectional view of a gear machined using the tooth profile milling method provided by this invention; Figure 4 This is a cross-sectional view of the gear teeth processed using the tooth profile milling method provided by the present invention.

[0042] In this embodiment, the gear teeth 2 used to process the gear 1 are machined on a cylindrical gear blank. The left and right sides of the gear teeth 2 are the first tooth surface 21 and the second tooth surface 22, respectively. Other structures of the gear 1 can refer to the prior art.

[0043] The tooth direction modification milling method comprises the following steps:

[0044] Step S1: forging of a tooth blank;

[0045] Step S2: rough machining of the tooth blank;

[0046] Step S3: tooth blank milling;

[0047] Step S4: carburizing and quenching;

[0048] Step S5: reference finishing;

[0049] Step S6: gear grinding processing to obtain a finished gear 1;

[0050] The step S3: tooth blank milling comprises:

[0051] Step S31: obtaining a gear helix angle and a tooth width, a first tooth surface modification depth and a second tooth surface modification depth of the tooth 2;

[0052] Step S32: calculating a first tooth surface modification helix angle and a second tooth surface modification helix angle according to the gear helix angle, the tooth width, the first tooth surface modification depth and the second tooth surface modification depth;

[0053] Step S33: milling processing the first tooth surface 21 of the tooth 2 according to the first tooth surface modification helix angle and reserving a target allowance;

[0054] Step S34: milling processing the second tooth surface 22 of the tooth 2 according to the second tooth surface modification helix angle.

[0055] Specifically, the milling method is mainly aimed at the tooth 2 with large modification, i.e. the tooth 2 with large tooth direction modification size, and the tooth 2 is regarded as being composed of the first tooth surface 21 with the first tooth surface modification helix angle β1 and the second tooth surface 22 with the second tooth surface modification helix angle β2, so that the first tooth surface 21 and the second tooth surface 22 are milled with different helix angles, and the grinding allowances of the two tooth surfaces after milling processing are consistent.

[0056] The gear milling method of the tooth direction modification provided by the application utilizes the data of the gear helix angle, the tooth width, the first tooth surface modification direction depth and the second tooth surface modification direction depth to calculate the first tooth surface modification direction helix angle of the first tooth surface 21 and the second tooth surface modification direction helix angle of the second tooth surface 22 respectively, so that the same grinding allowance and the same root digging amount of the upper, middle and lower different sections of the gear tooth 2 are pre-processed in the rough machining stage of the gear blank milling, thereby ensuring that the upper, middle and lower different sections of the gear tooth 2 have basically the same grinding allowance in the gear grinding processing procedure after the carburizing and quenching process, and ensuring that the hardened layer depth of each section of the gear tooth 2 is consistent and the tooth root transition curve appearance is consistent after the gear grinding, and finally realizing the consistency of the tooth surface bearing capacity and the tooth root bending strength of the gear tooth 2.

[0057] In some embodiments, the step further comprises, before the milling processing of the second tooth surface 22 of the gear tooth 2 according to the second tooth surface modification direction helix angle:

[0058] obtaining the pitch circle diameter of the gear 1;

[0059] calculating a target angle according to the pitch circle diameter, the first tooth surface modification direction depth and the second tooth surface modification direction depth;

[0060] rotating the gear 1 by the target angle.

[0061] Specifically, the target angle is calculated by using the pitch circle diameter of the gear 1, and after the first tooth surface 21 of the gear tooth 2 is processed, the gear 1 only needs to be rotated by the target angle, which is high in precision and convenient to control.

[0062] In some embodiments, the step of rotating the gear 1 by the target angle comprises rotating a workbench carrying the gear 1 by the target angle.

[0063] In some embodiments, the target angle α is calculated according to formula (1):

[0064]

[0065] wherein K is the pitch circle diameter, c is the first tooth surface modification direction depth, and e is the second tooth surface modification direction depth.

[0066] In some embodiments, the target allowance M=(c+e) / 2+(0.8-1.2)mm, wherein c is the first tooth surface modification direction depth and e is the second tooth surface modification direction depth; specifically, the target allowance is selected based on the milling normal line by ensuring that the second tooth surface 22 has sufficient allowance for milling.

[0067] In some embodiments, the first tooth surface modification depth and the second tooth surface modification depth are different in value. That is, the method is mainly aimed at the processing of the gear tooth 2 with asymmetric first tooth surface 21 and second tooth surface 22, by regarding the large modification gear 1 as the first tooth surface 21 and the second tooth surface 22 having different helix angles, the first tooth surface modification depth and the second tooth surface modification depth are calculated respectively, and the first tooth surface 21 and the second tooth surface 22 are processed respectively, so as to ensure the consistency of the grinding allowance, and further ensure the consistency of the performance.

[0068] In some embodiments, the first tooth surface modification helix angle β1 is calculated according to formula (2):

[0069]

[0070] Wherein, b is the tooth width, c is the first tooth surface modification depth, β is the gear helix angle, and n = 1.

[0071] In some embodiments, the second tooth surface modification helix angle β2 is calculated according to formula (3):

[0072]

[0073] Wherein, b is the tooth width, e is the second tooth surface modification depth, β is the gear helix angle, and n = 2.

[0074] In a specific embodiment, when the gear blank is milled, the first tooth surface modification helix angle β1 is milled first, and then the second tooth surface modification helix angle β2 is milled. In order to have sufficient allowance when milling the second tooth surface 22, the first tooth surface 21 must have sufficient target allowance M, which is preferably M = (c + e) / 2 + 0.1 mm. After completing the milling process of the first tooth surface 21, the workbench needs to be rotated by a predetermined angle α, and then the milling process of the second tooth surface 22 is carried out.

[0075] The gear milling method mills the helix angle of one tooth surface, and then rotates the workbench to mill the helix angle of the other tooth surface, so as to realize the processing of the gear 1 with the first tooth surface modification helix angle and the second tooth surface modification helix angle in the gear milling process. After the gear blank is milled and ground, the carburized layer is more uniform, and the grinding allowance is less. The tooth root circle depth is consistent, the tooth root corner remains straight, and the tooth root stress can be better uniform when the gear 1 is engaged.

[0076] The tooth direction modification milling method provided by the present application is described in detail above. The principle and implementation mode of the present application are described by applying specific examples in this paper, and the above example description is only used to help understand the method of the present application and its core idea. It should be pointed out that, for ordinary skilled persons in the technical field, some improvements and modifications can be made to the present application without departing from the principle of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A method of profile modification of a gear tooth by milling, for machining a gear tooth, the gear tooth having a first flank and a second flank on the left and right sides thereof, respectively, characterized in that, The method comprises the following steps: blank forging; rough machining; tooth milling; carburizing and quenching; finishing reference; grinding processing to obtain a finished gear; The step of tooth milling comprises: obtaining a gear helix angle and tooth width, first tooth surface modification depth and second tooth surface modification depth of the tooth; calculating a first tooth surface modification helix angle and a second tooth surface modification helix angle according to the gear helix angle, the tooth width, the first tooth surface modification depth and the second tooth surface modification depth; milling the first tooth surface of the tooth according to the first tooth surface modification helix angle and reserving a target allowance; milling the second tooth surface of the tooth according to the second tooth surface modification helix angle; The step of milling the second tooth surface of the tooth according to the second tooth surface modification helix angle further comprises: obtaining a pitch circle diameter of the gear; calculating a target angle according to the pitch circle diameter, the first tooth surface modification depth and the second tooth surface modification depth; rotating the gear by the target angle; The target angle α is calculated according to formula (1): Equation (1) wherein: is the pitch circle diameter, is the first flank modification depth, is the second flank modification depth; The first tooth surface modification helix angle β1 is calculated according to formula (2): Equation (2) wherein: is the tooth width, is the first flank modification depth, is the gear helix angle, n = 1; The second tooth surface modification helix angle β2 is calculated according to formula (3): Equation (3) wherein: is the tooth width, is the second flank modification depth, is the gear helix angle, n = 2.

2. The method of modifying the profile of a gear cutter according to claim 1 wherein, The step of rotating the gear by the target angle comprises rotating a workbench carrying the gear by the target angle.

3. The method of modifying the profile of a gear tooth by hobbing as defined in claim 1 wherein, The target allowance M=(c+e) / 2+(0.8~1.2)mm, wherein c is the first tooth surface modification depth and e is the second tooth surface modification depth.

4. The method of gulleting a cutter according to claim 1, wherein, The first tooth surface modification depth and the second tooth surface modification depth are different in value.

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