Self-centering measurement method for bevel teeth of forged bevel gear of differential mechanism

Abstract

The invention relates to the technical field of bevel gear detection, in particular to a self-centering measuring method for bevel teeth of a forged bevel gear of a differential mechanism, which comprises the following steps of: selecting a three-coordinate measuring machine with a self-centering (curve function) function to obtain a self-centering point coordinate and a self-centering point vector direction; and the conical axis is the reference established by the conical teeth. The invention provides a brand-new detection method for tooth profile precision of a forged bevel gear. By adopting the scheme, the measurement repetition precision is improved; the requirement for detection after machining of the forged bevel gear is omitted, and rapid detection of the tooth profile precision and the tooth surface shape of the bevel gear in the forging production process is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of bevel gear detection, and in particular to a self-centering measurement method for bevel teeth of a forged bevel gear of a differential. Background Art

[0002] Differential bevel gear is an important part of automobile differential, which is installed to adjust the speed difference between left and right wheels. The tooth profile accuracy and tooth surface shape of bevel gear also directly determine the gear quality. Usually the manufacturing process of bevel gear is: forging blank → machining → heat treatment → machining → inspection and packaging, among which the gear quality inspection of forging blank is particularly important.

[0003] There are two main solutions for the quality inspection of forged blank gears: The first solution is to use the blank benchmark for inspection. When this solution is adopted, the blank benchmark is affected by filling, resulting in low measurement repeatability. The second solution is to machine the blank first, and then use the machined benchmark for gear quality inspection. This solution is time-consuming and costly, and the measurement results are also affected by the machining quality, so it cannot truly reflect the gear quality of the forged blank. Summary of the invention

[0004] In order to solve the problem of inaccurate measurement results caused by using existing gears as references for detection in the prior art, the present invention provides a self-centering measurement method for bevel teeth of forged bevel gears of a differential with improved measurement repetition accuracy.

[0005] The technical solution adopted by the present invention to solve its technical problem is:

[0006] A self-centering measurement method for bevel teeth of a forged bevel gear of a differential comprises the following steps:

[0007] S1: The small end plane of the bevel gear tooth is used to locate the first direction, that is, the Z-axis direction and the Z-axis origin of the rectangular coordinate system; the symmetric center of the bevel gear tooth groove locates the second direction, that is, the X-axis direction or the Y-axis direction of the rectangular coordinate system, and the major diameter of the bevel gear locates the origin of the X-axis and the Y-axis to form the workpiece XYZ coordinate system;

[0008] S2: A first circle and a second circle are obtained at the small end and the large end of the tooth groove of the bevel gear, respectively. The first circle and the second circle have equal diameters and are in contact with two side surfaces of the tooth groove. The center points of the first circle and the second circle are connected to form a center line.

[0009] S3: The XYZ coordinates of the center point of the first circle at the small end are used as the self-centering point;

[0010] S4: Output the angles between the center line of the first circle and the second circle and the X-axis, Y-axis and Z-axis respectively;

[0011] S5: The self-centering point vector direction (9) is perpendicular to the line connecting the center of the circle, and the angles between the self-centering point and the +X axis, the +Y axis and the +Z axis are calculated respectively;

[0012] S6: Calculate the I vector from the center point = cos(90+β), J vector = cos(90) = 0; K vector = cos(β);

[0013] S7: The coordinates of the center point of the first circle at the small end of S3 are combined with the vector calculated in S6 to form a point. The triggering mode of this point is self-centering. The mode is changed to midpoint. These points are used to construct a cone, in which the axis of the cone is the reference of the bevel gear.

[0014] Furthermore, in the created XYZ coordinate system, the second direction of the bevel tooth groove center positioning is -X direction, the angle between the center line and the X axis is β, the angle between the center line and the Y axis is 90°, and the angle between the center line and the Z axis is γ; and the self-centering point vector direction (9) is perpendicular to the center line, then the angle between the self-centering point and the +X axis is (90+β)°, the angle between the self-centering point and the +Y axis is 90°, and the angle between the self-centering point and the +Z axis is β°, then I vector = cos(90+β), J vector = cos(90) = 0; K vector = cos(β).

[0015] Further, a three-coordinate measuring machine with self-centering and curve functions is selected, and S2 includes the following steps:

[0016] S211: Confirm the cone angle α of the bevel gear pitch from the drawing;

[0017] S212: constructing planes perpendicular to the pitch cone angle α at the small end and the large end of the center of the bevel tooth groove, intercepting the digital model, and generating a first contour line and a second contour line;

[0018] S213: The first contour line and the second contour line are respectively created as a first 3D curve and a second 3D curve;

[0019] S214: Call the circle fitting function of the curve profile, select the first 3D curve and the second 3D curve as elements, input the diameter of the probe at the diameter, fit the first fitting circle and the second fitting circle, and connect the centers of the first fitting circle and the second fitting circle to form a 3D line.

[0020] Further, in S214, the selection of the input probe diameter can be obtained in the following manner: the selection of the probe diameter is based on the size of the conical tooth groove, and the probe at the small end and the large end must simultaneously ensure that it is tangent to both side surfaces of the tooth groove and cannot contact the bottom of the tooth groove, and the tangent position is close to the middle of the tooth groove.

[0021] Further, a three-coordinate measuring machine with a self-centering function is selected, and S2 includes the following steps:

[0022] S221: In the stylus management, change the stylus radius value to "0". Use the stylus to measure one point at the small end and one point at the large end as the first point and the second point. The two points are connected to form a straight line. When measuring, make sure that the stylus contacts the two side surfaces of the tooth groove.

[0023] Furthermore, in S3, the probe radius value is first changed from "0" to an actual value, and then the measuring point at the small end is the self-centering point.

[0024] Furthermore, the tangent position of the measuring needle to the small end portion and the large end portion is close to the middle position of the tooth groove.

[0025] Beneficial effects: The present invention provides a new detection method for the tooth profile accuracy of forged bevel gears; the adoption of this scheme improves the measurement repeatability accuracy; eliminates the need for re-detection after forged bevel gear machining, and realizes the rapid detection of bevel gear tooth profile accuracy and tooth surface shape during the forging production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0027] Figure 1 This is a schematic diagram of the structure of the first fitting circle and the second fitting circle of Example 1;

[0028] Figure 2 Schematic diagram of the cone angle structure of the bevel gear pitch of Example 1;

[0029] Figure 3 Schematic diagram of the self-centering vector point vector;

[0030] Figure 4 This is a schematic diagram of the straight line of Example 2.

[0031] 1. Tooth groove, 1-1, small end part, 1-2, large end part, 2. Tooth small end plane, 3. Taper tooth major diameter, 4. First contour line, 5. Second contour line, 6. First fitting circle, 7. Second fitting circle, 8. 3D line, 9. Self-centering point vector direction, 10. First point, 11. Second point, 12. Straight line. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0034] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the present invention. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0035] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0036] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0037] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0038] The invention relates to a three-coordinate self-centering measurement method for realizing the detection of topological diagrams, tooth profile accuracy, form and position tolerance and other measurement items based on bevel gears.

[0039] A self-centering measurement method for bevel teeth of a forged bevel gear of a differential comprises the following steps:

[0040] S1: The bevel gear tooth small end plane 2 is used to locate the first direction, that is, the Z-axis direction and the Z-axis origin of the rectangular coordinate system; the symmetry center of the bevel gear tooth groove 1 locates the second direction, that is, the X-axis direction or the Y-axis direction of the rectangular coordinate system, and the bevel gear major diameter 3 locates the origin of the X-axis and the Y-axis to form the workpiece XYZ coordinate system;

[0041] S2: A first circle and a second circle are obtained at the small end portion 1-1 and the large end portion 1-2 of the tooth groove 1 of the bevel gear, respectively. The first circle and the second circle have equal diameters and are in contact with two side surfaces of the tooth groove 1. The center points of the first circle and the second circle are connected to form a center line.

[0042] S3: The XYZ coordinates of the center point of the first circle of the small end portion 1-1 are used as the self-centering point;

[0043] S4: Output the angles between the center line of the first circle and the second circle and the X-axis, Y-axis and Z-axis respectively;

[0044] S5: Assume that the second direction of the center positioning of the bevel tooth groove 1 in the created XYZ coordinate system is -X direction, the angle between the center line and the X axis is β, the angle between the center line and the Y axis is 90°, and the angle between the center line and the Z axis is γ; and the self-centering point vector direction 9 is perpendicular to the center line, then the angle between the self-centering point and the +X axis is 90+β°, the angle between the self-centering point and the +Y axis is 90°, and the angle between the self-centering point and the +Z axis is β°;

[0045] S6: Calculate I vector = cos(90+β), J vector = cos(90) = 0; K vector = cos(β);

[0046] S7: The coordinates of the center of the first circle of the small end part 1-1 in S3 are combined with the vector calculated in S6 to form a point. The triggering mode of this point is self-centering. The mode is changed to midpoint. These points are used to construct a cone, in which the axis of the cone is the reference of the bevel gear.

[0047] Specifically include the following embodiments:

[0048] Embodiment 1:

[0049] Use digital analog detection, the steps are as follows

[0050] Step 1: Select the testing equipment;

[0051] CMM with self-centering and curve capabilities.

[0052] Step 2: Choose the appropriate probe diameter;

[0053] like Figure 1 The selection of the probe diameter is based on the size of the conical tooth groove 1. At the small end 1-1 and the large end 1-2, the probe must be tangent to both sides of the tooth groove 1 and cannot contact the bottom of the tooth groove. The best tangent position is close to the middle of the tooth groove.

[0054] Step 3: Create a coordinate system;

[0055] The small end plane 2 of the bevel gear (the bevel gear here is optional but not limited to forged bevel gears) is used to locate the first direction, that is, the Z-axis direction and the Z-axis origin of the rectangular coordinate system; the symmetrical point of the bevel tooth groove 1 locates the second direction, that is, the X-axis direction or the Y-axis direction of the rectangular coordinate system, and the major diameter 3 of the bevel gear locates the origin of the X-axis and the Y-axis to form the workpiece XYZ coordinate system.

[0056] Step 4: Determine the XYZ coordinates of the bevel gear self-centering point;

[0057] like Figure 2 , confirm the cone angle α of the bevel gear pitch from the drawing;

[0058] like Figure 1, construct planes perpendicular to the pitch cone angle α at the small end portion 1-1 and the large end portion 1-2 of the bevel tooth groove center, intercept the digital model, and generate two first contour lines 4 and second contour lines 5;

[0059] Will Figure 1 The first contour line 4 and the second contour line 5 are created as a first 3D curve and a second 3D curve respectively;

[0060] Call the circle fitting function of the curve profile, select the first 3D curve and the second 3D curve as elements, enter the diameter of the probe in the diameter field, and fit a circle, such as Figure 1 A first fitting circle 6 and a second fitting circle 7;

[0061] The coordinates of the center X, Y and Z of the first fitting circle 6 of the output small end are the coordinates of the self-centering point of the bevel gear.

[0062] Step 5: Determine the vectors I, J, and K of the bevel gear self-centering point;

[0063] like Figure 3 , call the callback function to form a 3D line 4 with the centers of the first fitting circle 6 and the second fitting circle 7;

[0064] Output the angles between the 3D line 4 and the X-axis, the Y-axis and the Z-axis respectively;

[0065] like Figure 3 , assuming that the second direction of the bevel tooth groove center positioning in the coordinate system created in step 3 is the -X direction, the angle between the 3D line 6 and the X axis is β, the angle between the 3D line 6 and the Y axis is 90°, and the angle between the 3D line 6 and the Z axis is γ; and the self-centering point vector direction 9 is perpendicular to the 3D line 6, then the angle between the self-centering point 7 and the +X axis is (90+β)°, the angle between the self-centering point 7 and the +Y axis is 90°, and the angle between the self-centering point 7 and the +Z axis is β°.

[0066] Calculate I vector = cos(90+β), J vector = cos(90) = 0; K vector = cos(β).

[0067] Regardless of the direction of the bevel tooth groove center positioning, the purpose is to calculate the angle between the self-centering point and the +X, +Y and +Z axes respectively through the 3D line formed by the center of the fitting circle, and then calculate the cosine value.

[0068] Step 6: Create a self-centering point;

[0069] Call up the point element and enter the coordinate values ​​confirmed in step 4 in the X, Y and Z nominal values; enter the vector confirmed in step 5 in the I, J and K nominal values.

[0070] The trigger form of the point is set to self-centering and the mode is changed to midpoint.

[0071] Step 7: Create the bevel gear axis, measure and evaluate.

[0072] The self-centering points are rotated in an array to ensure that each tooth groove outputs a self-centering point, and then the element point recall function is called to construct the self-centering points into a cone. The axis of the cone is the reference established by the bevel gear itself. Under this reference, relevant gear quality tests can be performed.

[0073] Embodiment 2:

[0074] Without using digital-analog detection, the steps are as follows:

[0075] Step 1: Select the testing equipment;

[0076] Coordinate measuring machine with self-centering function.

[0077] Step 2: Choose the appropriate probe diameter;

[0078] like Figure 1 The selection of the probe diameter is based on the size of the conical tooth groove 1. At the small end 1-1 and the large end 1-2, the probe must be tangent to both sides of the tooth groove and cannot contact the bottom of the tooth groove. The best tangent position is close to the middle of the tooth groove.

[0079] Step 3: Create a coordinate system;

[0080] The tooth small end plane 2 of the bevel gear (here the bevel gear can be selected but not limited to the forged bevel gear) is used to locate the first direction, that is, the Z-axis direction and the Z-axis origin of the rectangular coordinate system; the symmetrical point of the bevel tooth groove 1 locates the second direction, that is, the X-axis direction or the Y-axis direction of the rectangular coordinate system, and the bevel tooth major diameter 3 locates the origin of the X-axis and the Y-axis to form the workpiece XYZ coordinate system. The bevel tooth groove center locates the second direction, which is the key to establish the coordinate system.

[0081] Step 4: Determine the vectors I, J, and K of the bevel gear self-centering point;

[0082] In the probe management, change the probe radius value to "0";

[0083] like Figure 4 , use the measuring needle to measure the first point 10 and the second point 11 at the small end 8 and the large end 9, and connect them to form a straight line 12. When measuring, make sure that the measuring needle is in contact with both sides of the tooth groove.

[0084] Output the angles between the straight line 12 and the X-axis, the Y-axis and the Z-axis respectively;

[0085] like Figure 4, assuming that the second direction of the bevel tooth groove center positioning in the coordinate system created in step 3 is the -X direction, the angle between the straight line 12 and the X-axis is β, the angle between the straight line 12 and the Y-axis is 90°, and the angle between the straight line 12 and the Z-axis is γ; and the self-centering point vector direction 9 is perpendicular to the straight line 12, then the angle between the self-centering point and the +X axis is (90+β)°, the angle between the self-centering point and the +Y axis is 90°, and the angle between the self-centering point and the +Z axis is β°.

[0086] Calculate I vector = cos(90+β), J vector = cos(90) = 0; K vector = cos(β).

[0087] Regardless of the direction of the bevel tooth groove center positioning, the purpose is to first calculate the angle between the center point and the +X, +Y and +Z axes through the straight line formed by the contact point, and then calculate the cosine value.

[0088] Step 5: Create a self-centering point;

[0089] In the stylus management, change the stylus radius value from "0" to the actual value;

[0090] like Figure 4 , measure point 8 at the small end, set the trigger mode to self-centering, change the point mode to midpoint, and then modify the nominal values ​​of I, J, and K to the vector confirmed in step 4. The same steps can be used to measure the self-centering point 9 at the large end.

[0091] Step 6: Create the bevel gear axis, measure and evaluate;

[0092] The self-centering points are rotated in an array to ensure that each tooth groove outputs a self-centering point, and then the element point recall function is called to construct the self-centering points into a cone. The axis of the cone is the reference established by the bevel gear itself. Under this reference, relevant gear quality tests can be performed.

[0093] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A self-centering measurement method for bevel teeth of forged bevel gears of differentials, characterized in that: The following steps are involved: S1: The small end plane (2) of the bevel gear tooth is used to locate the first direction, that is, the Z axis direction and the Z axis origin of the rectangular coordinate system; the symmetry center of the bevel gear tooth groove (1) is used to locate the second direction, that is, the X axis direction or the Y axis direction of the rectangular coordinate system, and the major diameter of the bevel gear (3) is used to locate the origin of the X axis and the Y axis, thereby forming the workpiece XYZ coordinate system; S2: A first circle and a second circle are obtained at the small end portion (1-1) and the large end portion (1-2) of the tooth groove (1) of the bevel gear, respectively. The first circle and the second circle have equal diameters and are in contact with two side surfaces of the tooth groove (1). The center points of the first circle and the second circle are connected to form a center line. S3: The XYZ coordinates of the center point of the first circle of the small end portion (1-1) are used as the self-centering point; S4: Output the angles between the center line of the first circle and the second circle and the X-axis, Y-axis and Z-axis respectively; S5: The self-centering point vector direction (9) is perpendicular to the line connecting the center of the circle, and the angles between the self-centering point and the +X axis, the +Y axis and the +Z axis are calculated respectively; S6: Calculate the I vector, J vector and K vector from the center point; S7: The coordinates of the center of the first circle at the small end (1-1) in S3 are combined with the vector calculated in S6 to form a point. The triggering mode of this point is self-centering. The mode is changed to midpoint. These points are used to construct a cone, in which the axis of the cone is the reference of the bevel gear.

2. The self-centering measurement method for the bevel teeth of a forged bevel gear of a differential according to claim 1, characterized in that: In the created XYZ coordinate system, the second direction of the symmetric center of the bevel tooth groove (1) is -X direction, the angle between the center line and the X axis is β, the angle between the center line and the Y axis is 90°, and the angle between the center line and the Z axis is γ; and the self-centering point vector direction (9) is perpendicular to the center line, then the angle between the self-centering point and the +X axis is (90+β)°, the angle between the self-centering point and the +Y axis is 90°, and the angle between the self-centering point and the +Z axis is β°, then I vector = cos(90+β), J vector = cos(90) = 0; K vector = cos(β).

3. The self-centering measurement method for the bevel teeth of a forged bevel gear of a differential according to claim 2, characterized in that: Select a three-dimensional coordinate measuring machine with self-centering and curve functions. S2 includes the following steps: S211: Confirm the cone angle α of the bevel gear pitch from the drawing; S212: constructing planes perpendicular to the pitch cone angle α at the central small end portion (1-1) and the large end portion (1-2) of the bevel tooth groove (1), respectively, intercepting the digital model, and generating a first contour line (4) and a second contour line (5); S213: The first contour line (4) and the second contour line (5) are created as a first 3D curve and a second 3D curve respectively; S214: Call the circle fitting function of the curve profile, select the first 3D curve and the second 3D curve as elements, input the diameter of the probe at the diameter, fit the first fitting circle (6) and the second fitting circle (7), and connect the centers of the first fitting circle (6) and the second fitting circle (7) to form a 3D line (8).

4. The self-centering measurement method for the bevel teeth of a forged bevel gear of a differential according to claim 3, characterized in that: In S214, the selection of the diameter of the input probe can be obtained in the following manner: the selection of the probe diameter is based on the size of the conical tooth groove (1), and the probe at the small end portion (1-1) and the large end portion (1-2) must simultaneously ensure that it is tangent to both sides of the tooth groove (1) and cannot contact the bottom of the tooth groove (1), and the tangent position is close to the middle position of the tooth groove (1).

5. The self-centering measurement method for bevel teeth of forged bevel gears of differential according to claim 2, characterized in that: Select a three-dimensional coordinate measuring machine with self-centering function. S2 includes the following steps: S221: In the stylus management, change the stylus radius value to "0". Use the stylus to measure one point at the small end (1-1) and one point at the large end (1-2) as the first point (10) and the second point (11). Connect the two points to form a straight line (12). When measuring, make sure that the stylus contacts both sides of the tooth groove (1).

6. The self-centering measurement method for the bevel teeth of a forged bevel gear of a differential according to claim 5, characterized in that: In S3, first change the probe radius value from "0" to the actual value, and then measure the point at the small end (1-1), which is the self-centering point.

7. The self-centering measurement method for the bevel teeth of a forged bevel gear of a differential according to claim 6, characterized in that: The tangent position of the measuring needle with the small end part (1-1) and the large end part (1-2) is close to the middle position of the tooth groove (1).

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