A bevel gear virtual assembly method

Abstract

The present application belongs to the technical field of gear assembly, and discloses a bevel gear virtual assembly method. The method can realize modeling of a pair of bevel gears through three-dimensional drawing software, and realize gear assembly, error adjustment and rotation of a small bevel gear by using coordinate transformation; the tooth surface contact area is obtained through interference elimination, contact mark simulation and mark edge optimization, and finally the backlash is obtained through a backlash obtaining step. The method can not only save the steps of grid division and grid quality control, but also quickly and accurately obtain the working tooth surface contact area and the backlash of the non-working tooth surface, and is simple in logic, easy to understand and program.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of gear assembly, and discloses a bevel gear virtual assembly method. BACKGROUND

[0002] As an indispensable core component of an automobile drive axle, a spiral bevel gear has the characteristics of stable transmission, low noise, strong load capacity and the like. Compared with a cylindrical gear, the spatial geometric shape of a tooth surface of a bevel gear is more complex, and the evaluation of the machining quality of the spiral bevel gear is more strict, and the adjustment of a tooth surface contact area, which is one of important indicators for measuring the machining quality of the spiral bevel gear, is very important. In order to make the spiral bevel gear pair work normally, the two gears must have a good tooth surface contact area and a proper meshing gap. The tooth surface contact area is more important. The tooth surface contact area refers to an actual contact position of tooth surfaces of a pair of spiral bevel gears in meshing operation, which is commonly referred to as a meshing mark. The shape, size and position of the tooth surface contact area have a direct influence on the balanced operation, service life and noise of the spiral bevel gear.

[0003] In the prior art, the methods for obtaining the tooth surface contact area of the spiral bevel gear include a rolling test, theoretical calculation and finite element calculation. The most common method is the finite element calculation, which realizes the simulation of the tooth surface contact area by establishing a gear model and performing mesh division. However, the mesh division needs a large amount of time, and the time consumption is relatively long. The quality of the mesh is good, and the simulation analysis effect is good. The quality of the mesh is poor, and the simulation analysis effect is poor. Therefore, the method of the finite element calculation not only has a relatively long time consumption, but also has unstable analysis effect quality. SUMMARY

[0004] The purpose of the application is to provide a bevel gear virtual assembly method capable of quickly and accurately obtaining a working tooth surface contact mark of a pair of gears and a tooth gap of a non-working tooth surface.

[0005] To achieve this purpose, the application adopts the following technical solutions:

[0006] A bevel gear virtual assembly method, comprising the following steps:

[0007] S10, a bevel gear model, an assembly coordinate system and a position transformation coordinate system are established, and gear assembly, error adjustment and rotation of a small bevel gear are realized through position transformation;

[0008] S20, a tooth surface and two front and rear tooth surfaces thereof are extracted and analyzed;

[0009] S30, interference elimination is performed to enable the two gears to normally mesh;

[0010] S40, contact mark simulation is performed to obtain a meshing ellipse and a tooth surface contact area;

[0011] S50, performing the imprint edge optimization to optimize the tooth surface contact area;

[0012] S60, performing the tooth gap acquisition.

[0013] As preferably, the step of interference elimination comprises:

[0014] S310, rotating the bevel pinion along the working rotational direction through coordinate transformation;

[0015] S320, measuring the distance between the analyzed tooth surface and the corresponding tooth surface of the bevel pinion, and determining that the interference has been eliminated when the minimum value of the three distances is less than a set threshold.

[0016] As preferably, the step of contact imprint simulation comprises:

[0017] S410, setting the rotation step and the number of steps of the bevel pinion, and rotating the bevel pinion through coordinate transformation;

[0018] S420, rotating the two meshing bevel gears each once through coordinate transformation according to the transmission ratio;

[0019] S430, rotating the bevel pinion around its own axis until the working tooth surface is tangent through coordinate transformation;

[0020] S440, judging the state of the two pairs of tooth surfaces of the analyzed tooth surface, repeating the steps of S420-S430 if the front tooth surface intersects, ending if the rear tooth surface intersects, and obtaining the contact ellipse if both tooth surfaces are apart, and ending the process.

[0021] As preferably, the step of working tooth surface tangency comprises:

[0022] S431, if the current state of the analyzed tooth surface is intersection or separation, rotating the bevel pinion by t° through coordinate transformation, judging the state of the analyzed tooth surface, and continuing to rotate the bevel pinion by t° if the original state is intersection or separation and the state remains unchanged after rotation; or proceeding to the next step if the original state is intersection or separation and the state changes after rotation.

[0023] S432, if the current state of the analyzed tooth surface is tangency, obtaining the contact point and the tangent point; if the current state of the analyzed tooth surface is intersection or separation, rotating the bevel pinion by t° / 2 through coordinate transformation, and continuing to rotate the bevel pinion by t° / 2 until the analyzed tooth surface is tangent to obtain the contact point and the tangent point, if the state remains unchanged or the intersection changes to separation or the separation changes to intersection after rotation.

[0024] As preferably, the step of imprint edge optimization comprises:

[0025] S510, extracting the tooth surface edge of the working tooth surface;

[0026] S520, using the bisection iterative method to make the print close to the edge of the tooth surface until the tooth surface contact area is obtained.

[0027] As preferably, the step of tooth gap obtaining comprises:

[0028] S610, under the premise of analyzing the tooth surface tangent to the tooth surface of the bevel pinion, reversely rotating the non-working tooth surface of the bevel pinion until tangent to the non-working tooth surface of the bevel gear;

[0029] S620, repeating step S610 for at least 3 times, recording the rotation angle, and taking the minimum value, i.e. the tooth gap of the gear is obtained.

[0030] As preferably, the step of gear assembly comprises:

[0031] S110, establishing an assembly coordinate system, and using coordinate transformation to position the bevel pinion to the assembly position;

[0032] S120, performing installation error adjustment.

[0033] As preferably, the step of installation error adjustment is to establish an error adjustment coordinate system, and using coordinate transformation to position the bevel pinion to realize error adjustment.

[0034] As preferably, the bevel gear virtual assembly method can be programmed and the three-dimensional drawing software can be secondarily developed to realize automatic acquisition of the tooth surface contact area and the tooth gap of the bevel gear.

[0035] As preferably, the three-dimensional drawing software is CATIA.

[0036] Beneficial effects: the present application realizes assembly, error adjustment and rotation of the bevel pinion through coordinate transformation, and accurately obtains the working tooth surface contact area and the tooth gap of the non-working tooth surface of the bevel gear through interference elimination, contact print simulation, print edge optimization and tooth gap obtaining steps. Not only the steps of grid division and quality control can be saved, but also accurate results can be obtained, and the logic is simple, easy to understand and program. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a step flow chart of the bevel gear virtual assembly method provided by the embodiment of the present application;

[0038] Figure 2 is a step flow chart of the contact print simulation provided by the embodiment of the present application;

[0039] Figure 3 is a step flow chart of the working tooth surface tangency provided by the embodiment of the present application. DETAILED DESCRIPTION

[0040] The application will be described in further detail below with reference to the drawings and embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the application and are not to be used to limit the application. In addition, it is to be understood that, for the purpose of description, only the parts related to the application are shown in the drawings rather than all the parts.

[0041] In the description of the application, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0042] In the present application, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "upper", "above" and "on" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "below", "under" and "under" of the first feature to the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0043] In the description of the present embodiment, the terms "upper", "lower", "right", and other orientation or position relationship are based on the orientation or position relationship shown in the drawings, which is only for the convenience of description and simplification of operation, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0044] The present embodiment provides a bevel gear virtual assembly method, which can use three-dimensional drawing software to virtually assemble a pair of bevel gears and obtain the tooth surface contact area and the backlash.

[0045] In the prior art, the methods for obtaining the tooth surface contact area of spiral bevel gears include rolling test, theoretical calculation and finite element calculation. The most common method is finite element calculation, which realizes the simulation of the tooth surface contact area by establishing a gear model and performing meshing. However, meshing requires a large amount of time, and the time-consuming is relatively long. If the mesh quality is good, the simulation analysis effect is good, and if the mesh quality is poor, the simulation analysis effect is poor. Therefore, the method of finite element calculation not only consumes a lot of time, but also the analysis effect quality is unstable.

[0046] To solve the above problems, as shown in the figure, the bevel gear virtual assembly method provided by the embodiment comprises the following steps: Figure 1

[0047] S10, a bevel gear model is established, and the bevel gear is assembled;

[0048] S20, the tooth surface and the front and rear tooth surfaces thereof are extracted and analyzed;

[0049] S30, interference elimination is performed to enable the two gears to be normally engaged;

[0050] S40, contact mark simulation is performed to obtain an engagement ellipse and a range of the engagement ellipse, i.e., a tooth surface contact area;

[0051] S50, mark edge optimization is performed to obtain the tooth surface contact area;

[0052] S60, tooth gap acquisition is performed.

[0053] The method does not need to perform mesh division, the time used is short, and the obtained result is accurate and stable.

[0054] Specifically, the steps of the gear assembly comprise:

[0055] S110, an assembly coordinate system is established, and a position transformation is performed on the small bevel gear by using coordinate conversion to move to an assembly position;

[0056] S120, installation error adjustment is performed.

[0057] It should be noted that the model establishment and the tooth surface contact area and tooth gap acquisition are performed by using a three-dimensional drawing software CATIA as a working environment. When a pair of engaged bevel gear pairs are established, each bevel gear is based on a default original coordinate system in CATIA, and the Z-axis of the original coordinate system is taken as an axis and located at the same position on the negative half-axis of the Z-axis to respectively establish the model of the engaged bevel gears. The purpose of this is to facilitate the establishment of the assembly coordinate system and the position transformation coordinate system of the small bevel gear. After the coordinate system to be transformed is established, the coordinate conversion command provided by CATIA is used to realize the position transformation of the small gear from the original coordinate system to the target position.

[0058] Next, the establishment of the coordinate system is described.

[0059] ​When establishing a coordinate system in CATIA, the default is to use the original coordinate system as the base. To establish a translation coordinate system, simply input the distance values ​​of the new coordinate system relative to the original coordinate system in the three directions, assuming the coordinate vectors are in the same direction. Of course, CATIA can also establish a rotation coordinate system, where the new coordinate system has a certain angle relative to the original coordinate system. To do this, substitute the vectors of the coordinate axes in the original coordinate system into the Rodrigues formula shown in Formula 1 below, and input the desired rotation angle to obtain the vectors of the three coordinate axes of the new coordinate system.

[0060] v1=cosθ×v(1-cosθ)(v×k)+sinθ×k×v (Formula 1)

[0061] Where: v: a unit vector;

[0062] k: Unit vector of the rotation axis;

[0063] θ: The unit vector of the rotation axis;

[0064] v1: The vector of v after rotating θ around k.

[0065] Although the small bevel gear moves to the position for meshing with the large bevel gear after coordinate transformation, there may still be installation errors. Therefore, position error adjustment is required to achieve the desired assembly effect. The position error adjustment process involves establishing an error adjustment coordinate system and using coordinate transformation to change the position of the small bevel gear to achieve error adjustment. The logic is simple and the operation is convenient.

[0066] The error adjustment coordinate system needs to be established by calculating the error translation coordinate system vector according to Formula 2 below. The installation error can then be eliminated by converting the small bevel gear to the error translation coordinate system using the coordinate transformation command in CATIA.

[0067]

[0068] Where: β is the angle between the axes;

[0069] α is the axial angle error;

[0070] P represents the axial error of the small bevel gear;

[0071] G represents the axial error of the large bevel gear;

[0072] E represents the offset distance error;

[0073] O x O y and O z The error translation coordinate system vector.

[0074] Simply transforming coordinates cannot achieve true meshing; tooth interference between the large and small bevel gears may occur. To solve this problem, interference cancellation is needed. The specific steps for interference cancellation are as follows:

[0075] S310. The small bevel gear is rotated along the working direction by coordinate transformation;

[0076] S320. Measure the distance between the analytical tooth surface of the large bevel gear and the two tooth surfaces before and after it and the corresponding tooth surface of the small bevel gear. When the minimum value of the three distances is less than the set threshold, the interference is considered to have been eliminated. If the minimum value of the three distances is still greater than the set threshold, repeat steps S310 and S320 until the interference is eliminated.

[0077] It should be noted that the rotation of the small gear is also achieved by first establishing a rotation coordinate system and then transforming it using the coordinate transformation command.

[0078] After eliminating interference, the contact imprint can be simulated to obtain the meshing ellipse, such as... Figure 2 As shown, the steps for simulating contact imprints are as follows:

[0079] S410. Set the rotational step size and number of steps of the small bevel gear, establish the required rotational coordinates, and adjust the small bevel gear through coordinate transformation;

[0080] S420. Establish the required coordinate system and transform the coordinates to make the two meshing bevel gears rotate once each according to the transmission ratio.

[0081] S430. Establish the required coordinate system and use coordinate transformation to make the small bevel gear rotate around its own axis until the working tooth surfaces are tangent.

[0082] S440. Analyze the state of the front and rear tooth surfaces. If the front tooth surfaces intersect, repeat steps S420 to S430. If the rear tooth surfaces intersect, the process ends. If both tooth surfaces are separated, a contact ellipse is obtained, and the process ends.

[0083] It should be noted that the rotation step size and number of steps can be adjusted according to the actual situation. A smaller rotation step size and more rotation steps result in higher accuracy. Furthermore, to simplify the operation process, the rotation of the large bevel gear is achieved through the relative rotation of the small bevel gear. Before performing contact imprint simulation, the tooth surface is extracted and offset by one end, optionally 6.35 micrometers, as the actual pigment surface. During the analysis of tooth meshing, the pigment surface will intersect with the small bevel gear, thus obtaining the contact ellipse. By repeatedly performing steps S410 to S440 and coinciding the obtained contact ellipses, the range of the contact ellipse, i.e., the tooth surface contact area, can be obtained.

[0084] Furthermore, the steps for achieving tangency between the working tooth surfaces are explained, such as... Figure 3As shown, it includes:

[0085] S431. If the current state of the analyzed tooth surface is intersecting or disjoint, rotate the small bevel gear by t° by establishing the required coordinate system and performing coordinate transformation. Determine the state of the analyzed tooth surface. If the original state is intersecting or disjoint and the state remains the same after rotation, continue rotating the small bevel gear by t°. If the original state is intersecting or disjoint and the state changes from intersecting to disjoint or from disjoint to intersecting after rotation, it indicates that the rotation angle is too large, so proceed to the next step. If the state is tangent after rotation, also proceed to the next step.

[0086] S432. If the current state of the analyzed tooth surface is tangent, then the contact point and the tangent point are obtained; if the current state of the analyzed tooth surface is intersecting or separating, the small bevel gear is rotated by t° / 2 through coordinate transformation. If the state remains unchanged after rotation, or the intersecting becomes separating, or the separating becomes intersecting, then the small bevel gear is rotated by t° / 2 until the analyzed tooth surface is tangent and the contact point and the tangent point are obtained.

[0087] The steps for analyzing the tangency of the working tooth surfaces can also be understood as follows: Give the small bevel gear a rotation step of t°, allowing the tooth surfaces to gradually search in the tangential direction until the analyzed tooth surfaces change from intersecting to disjoint or vice versa. This yields a fixed interval containing the solution domain. Then, using a bisection method, the interval containing the solution is halved each time, gradually approximating the solution domain until the tangency of the tooth surfaces is finally achieved. This method is convenient to operate and has simple logic.

[0088] Furthermore, to achieve higher accuracy in the obtained tooth surface contact area, an imprint edge optimization method can be employed. Specifically, imprint edge optimization includes the following steps:

[0089] S510, Extract the edge of the working tooth surface;

[0090] S520. Use the bisection method to iterate and move the contact ellipse closer to the edge of the tooth surface until the tooth surface contact area is obtained.

[0091] The binary iterative method involves repeatedly performing the steps of working with the tooth surface tangent, causing the contact ellipse to move closer to the tooth surface edge, ultimately obtaining the optimized range of the contact ellipse, which is the optimized tooth surface contact area. The logic is simple, easy to understand, and easy to program.

[0092] Furthermore, assuming the tooth surface is tangent to the tooth surface of the small bevel gear, the backlash angle can be obtained by rotating the small bevel gear in the opposite direction. The backlash distance can then be calculated using the chord length formula. Specifically, the steps for obtaining the backlash are as follows:

[0093] S610. Under the premise that the tooth surface of the small bevel gear is tangent to the tooth surface of the large bevel gear, rotate the non-working tooth surface of the small bevel gear in the opposite direction until it is tangent to the non-working tooth surface of the large gear.

[0094] S620. Repeat step S610 at least 3 times, record the rotation angle, take the minimum value, and calculate the gear backlash using the chord length formula.

[0095] The above describes the method steps and logic of the virtual assembly method for bevel gears provided in this embodiment. The logic is clear and simple, and easy to understand. Those skilled in the art can program the logic method and perform secondary development in conjunction with CATIA to achieve automatic acquisition of the tooth surface contact area and tooth clearance of the bevel gear, reducing manual labor while obtaining more accurate and faster results.

[0096] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A virtual assembly method for bevel gears, characterized in that, Includes the following steps: S10. Establish models of the small bevel gear and the large bevel gear, and assemble the small bevel gear and the large bevel gear; S20. Extract the analytical tooth surface of the large bevel gear and the front and rear tooth surfaces of the analytical tooth surface; S30. Perform interference elimination to enable the small bevel gear and the large bevel gear to mesh normally; S40. Perform contact imprint simulation to obtain the meshing ellipse and tooth surface contact area; S50. Perform imprint edge optimization to optimize the tooth surface contact area; S60, Obtain the tooth gap; The steps for simulating contact imprints include: S410. Set the rotation step and number of steps of the small bevel gear, and rotate the small bevel gear; S420, the meshing large bevel gear and the meshing small bevel gear each rotate once according to the transmission ratio; S430, the small bevel gear rotates around its own axis until the working tooth surfaces are tangent, the working tooth surface being the analysis tooth surface and the tooth surface of the small bevel gear corresponding to it; S440. Determine the contact state between the front and rear tooth surfaces of the analyzed tooth surface and their corresponding small bevel gear tooth surfaces. If the front tooth surface of the analyzed tooth surface intersects with its corresponding small bevel gear tooth surface, repeat steps S420 to S430. If the rear tooth surface of the analyzed tooth surface intersects with its corresponding small bevel gear tooth surface, the process ends. If both the front and rear tooth surfaces of the analyzed tooth surface are separate from their corresponding small bevel gear tooth surfaces, a contact ellipse is obtained, and the process ends. The step of making the working tooth surfaces tangent includes: S431. If the current contact state between the analyzed tooth surface and its corresponding small bevel gear tooth surface is intersecting or disjoint, rotate the small bevel gear by t° and determine the contact state between the analyzed tooth surface and its corresponding small bevel gear tooth surface. If the original state is intersecting or disjoint, and the original state remains after rotation, continue rotating the small bevel gear by t°. If the original state is intersecting or disjoint, and the original state changes after rotation, proceed to the next step. S432. If the current contact state between the analyzed tooth surface and its corresponding small bevel gear tooth surface is tangent, then the contact point and tangency point are obtained; if the current contact state between the analyzed tooth surface and its corresponding small bevel gear tooth surface is intersecting or disjoint, rotate the small bevel gear by t° / 2. If the contact state remains unchanged after rotation, or the intersecting state changes to disjoint, or the disjoint state changes to intersecting, then continue rotating the small bevel gear by t° / 2 until the analyzed tooth surface and its corresponding small bevel gear tooth surface are tangent, thus obtaining the contact point and tangency point. The steps for obtaining the tooth gap include: S610. Under the premise that the analyzed tooth surface is tangent to the tooth surface of the small bevel gear, rotate the non-working tooth surface of the small bevel gear in the opposite direction until it is tangent to the non-working tooth surface of the large bevel gear. S620. Repeat step S610 at least 3 times, record the rotation angle, and take the minimum value to obtain the gear backlash.

2. The virtual assembly method for bevel gears according to claim 1, characterized in that, The interference elimination steps include: S310, The small bevel gear rotates along the working direction; S320. Measure the distance between the analytical tooth surface and the two tooth surfaces before and after it on the large bevel gear and the corresponding tooth surface of the small bevel gear. When the minimum value of the three distances is less than the set threshold, the interference is considered to have been eliminated.

3. The virtual assembly method for bevel gears according to claim 1, characterized in that, The steps for optimizing the imprint edge include: S510. Extract the edge of the working tooth surface; S520. Use the bisection iterative method to move the imprint closer to the edge of the tooth surface until the tooth surface contact area is obtained.

4. The virtual assembly method for bevel gears according to any one of claims 1 to 3, characterized in that, The gear assembly steps include: S110. Establish an assembly coordinate system and use coordinate transformation to perform position transformation on the small bevel gear to move it to the assembly position. S120. Adjust the installation error.

5. The virtual assembly method for bevel gears according to claim 4, characterized in that, The steps for adjusting the installation error are as follows: establish an error adjustment coordinate system, and use coordinate transformation to perform position transformation on the small bevel gear to achieve error adjustment.

6. The virtual assembly method for bevel gears according to any one of claims 1 to 3, characterized in that, The virtual assembly method for bevel gears can be programmed and the 3D modeling software can be further developed to achieve automatic acquisition of the tooth surface contact area and tooth clearance of the bevel gears.

7. The virtual assembly method for bevel gears according to claim 6, characterized in that, The 3D modeling software is CATIA.

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