Method for evaluating symmetry degree of herringbone gear

Abstract

The invention belongs to the field of gear detection, and particularly relates to a herringbone gear symmetry degree evaluation method. An existing herringbone gear symmetry degree evaluation method cannot quantitatively and accurately predict the overall symmetry degree error of gear teeth on the two sides of a herringbone gear. According to the invention, the herringbone gear is coaxially installed on a rotating shaft of a tooth measuring machine operation table; taking upper and lower end faces outside left and right gear teeth of the herringbone gear as measurement references to determine a symmetric central plane, and establishing a coordinate system; parameters of the herringbone gear are input into a tooth measuring machine, and spiral lines on the same sides of all gear teeth of the upper gear and the lower gear are obtained through measurement of the tooth measuring machine; and the alignment degree deviation fAi of all tooth surface vertexes on the same side, the alignment degree difference fAu of adjacent teeth, the total alignment degree deviation FA of the herringbone gear and the symmetry degree deviation fAS of the herringbone gear are calculated, and the herringbone gear is evaluated based on various calculation results. According to the scheme, the overall symmetry error condition of the gear teeth on the two sides of the herringbone gear can be quantitatively and accurately evaluated, and a powerful guarantee is provided for production.

Description

Technical Field

[0001] The invention belongs to the field of gear detection, and in particular relates to a method for evaluating the symmetry of a herringbone gear. Background Art

[0002] Herringbone gears are widely used in transmission systems such as automobiles and aviation. They are often used in high-speed and heavy-load conditions due to their high overlap, high load capacity, small axial load and stable operation. Herringbone gears are equivalent to two helical gears with equal helical angles and opposite rotation directions connected rigidly. Therefore, compared with helical gears, herringbone gears have two axial forces in opposite directions and similar in size, and these two axial forces can be offset as much as possible.

[0003] Since the two gears with opposite rotation directions of the herringbone gear will have deviations during processing and manufacturing, the left and right gear teeth of the herringbone gear are asymmetric, which further causes the axial load and uneven load distribution. Therefore, in order to improve these shortcomings as much as possible, it is required to improve the processing accuracy of the herringbone gear. The most important indicator for judging the processing accuracy of the herringbone gear is the symmetry error.

[0004] At present, the symmetry error of herringbone gears is mainly measured by three-coordinate or gear measuring machines to measure the symmetry error of 1 to 4 gear teeth on the circumference. The three-coordinate measurement method only determines the deviation of a certain coordinate point on the tooth surface of a certain gear. When the two-point three-coordinate measurement of the symmetry error is carried out, due to the tooth modification and processing and manufacturing errors, the pitch circle and modification amount of the left and right helical gear teeth are asymmetric. It is difficult to determine the positions of the two measurement points on the tooth surface of the left and right helical gears, which reduces the accuracy of the measurement.

[0005] Therefore, the existing herringbone gear symmetry evaluation method cannot quantitatively and accurately predict the overall symmetry error of the teeth on both sides of the herringbone gear. Summary of the invention

[0006] The purpose of the present invention is to provide a method for quantitatively and accurately evaluating the symmetry of herringbone gears.

[0007] The present invention provides a method for evaluating the symmetry of a herringbone gear, the method comprising the following steps:

[0008] S1. Install the herringbone gear coaxially on the rotary shaft of the gear measuring machine operating table;

[0009] S2. Determine the symmetry center plane using the upper and lower end faces of the outer sides of the left and right gear teeth of the herringbone gear as the measurement reference, and establish a coordinate system;

[0010] S3. Select a probe with a suitable head diameter. The size of the probe head must be sufficient to extend into the pitch circle position of the tooth groove;

[0011] S4, inputting the parameters of the herringbone gear into a gear measuring machine, and measuring the same-side helical lines of all the gear teeth of the upper gear and the lower gear by the gear measuring machine;

[0012] S5. Calculate the deviation distance of all tooth surface vertices on the same side relative to the symmetric center plane, which is recorded as the alignment deviation f Ai , i represents the number of teeth, and the range of i is from 1 to the total number of teeth;

[0013] S6. Calculate the maximum absolute value of the algebraic difference between the alignment of adjacent gear teeth, which is recorded as the alignment difference f between adjacent gear teeth. Au ,Pick Au :f Au =max|f Ai+1 -f Ai |;

[0014] S7. Calculate the algebraic difference between the maximum and minimum values ​​of the symmetry deviation of all teeth of the herringbone gear, and record it as the total alignment deviation of the herringbone gear F. A :F A =max(f Ai )-min(f Ai );

[0015] S8. Calculate the arithmetic mean of all adjacent tooth alignment deviations, recorded as the herringbone gear symmetry deviation f AS :

[0016]

[0017] S9. Evaluate the herringbone gears based on various calculation results.

[0018] Advantageously, in S1, the lower shaft hole of the herringbone gear is assembled on the lower center of the center tooling or on the part fixing fixture.

[0019] Advantageously, the rotating platform of the gear measuring machine is rotated, and the upper and lower journals of the herringbone gear are aligned respectively using a micrometer.

[0020] Advantageously, in S2, the symmetry center plane is determined by measuring the tooth widths of the upper gear and the lower gear, and half the tooth width G1 of the upper gear and half the tooth width G3 of the lower gear are calculated. The upper gear end face or the lower gear end face of the herringbone gear is used as the measurement reference A, and the outer end face distance of the herringbone gear is obtained by measurement, and the distance G2 from the measurement reference A to half the tooth width of the gear on the other side is determined.

[0021] Advantageously, the rotation axis is used as the Z axis of the coordinate system, and the symmetry center plane is used as the plane where the XY axes are located.

[0022] Advantageously, in S4, the parameters of the herringbone gear include the number of gear teeth, module, pressure angle, helix angle and rotation angle. The gear measuring machine calculates the gear pitch circle size and makes the probe touch the pitch circle position of the tooth surface according to the rotation angle.

[0023] Advantageously, the starting angle of the first tooth helix is ​​determined by the following formula:

[0024] θ=Z×tanβ b / r

[0025] Z is the Z-axis coordinate value of the starting point, β b is the base circle helix angle, and r is the pitch circle radius.

[0026] Advantageously, the starting angle of the helix of the subsequent teeth is calculated by the number of teeth.

[0027] Advantageously, the adjacent tooth alignment difference f Au Symmetry deviation f of herringbone gear AS The single pitch limit deviation accuracy level should be consistent with the existing design parameter standard; the total deviation of the herringbone gear alignment F A Not greater than the experience value.

[0028] Advantageously, the total deviation F of the herringbone gear alignment A Not greater than the empirical value of 0.02.

[0029] Beneficial effects: This solution can quantitatively and accurately evaluate the overall symmetry error of the gear teeth on both sides of the herringbone gear, providing strong guarantee for production. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the measurement and installation of herringbone gears;

[0031] Figure 2 A schematic diagram of the method for determining the central plane of symmetry;

[0032] Figure 3 This is a measurement schematic diagram based on the above end surface;

[0033] Figure 4 This is a schematic diagram of the value of neutral deviation;

[0034] Figure 5 It is a schematic diagram of tooth tip alignment deviation;

[0035] Figure 6 Schematic diagram of calculation results of the embodiment. DETAILED DESCRIPTION

[0036] like Figure 1As shown in the installation diagram of the herringbone gear symmetry measurement, first select the lower center 2 of the center tooling or the part fixing fixture according to the size of the gear and assemble it on the rotating shaft of the gear measuring machine operating table, and assemble the lower shaft hole of the herringbone gear 4 on the lower center 2 of the center tooling or the part fixing fixture.

[0037] Next, turn the rotating platform of the gear measuring machine, use a micrometer to align the upper and lower journals of the herringbone gear 4 respectively, use a micrometer to measure the runout of the upper and lower journals to ensure that the runout is consistent, and through fine-tuning, ensure that the axes of the upper and lower journals 5 of the herringbone gear are consistent with the rotating axis of the gear measuring machine.

[0038] Next, assemble the upper center 1 of the gear measuring machine into the upper shaft hole of the herringbone gear. This step ensures that the part is fixed on the rotating platform of the gear measuring machine by the upper and lower centers, so as to ensure the stable rotation of the herringbone gear when the main shaft of the gear measuring machine is driven to rotate.

[0039] See also Figure 2 and Figure 3 , the upper and lower end faces of the outer sides of the left and right gear teeth of the herringbone gear are used as the measurement reference to determine the symmetry center plane. The tooth widths of the upper and lower gears are measured by the probe 3, and half the tooth width G1 of the upper gear and half the tooth width G3 of the lower gear are calculated. The upper gear end face of the herringbone gear 4 is used as the measurement reference A, and the distance between the outer end faces of the upper and lower gears is measured, so that the distance G2 from the measurement reference A to half the tooth width of the lower gear can be determined. The rotary axis is used as the Z axis of the coordinate system, and the symmetry center plane is used as the plane where the XY axis is located.

[0040] Under the condition that no interference or collision occurs, a probe 3 with a suitable head diameter is selected, and the head size of the probe 3 must be guaranteed to extend into the pitch circle position of the tooth groove.

[0041] The dimension can also be determined in the same manner using the lower gear end face of the herringbone gear 4 as the measurement reference A.

[0042] like Figure 4 As shown in the figure, the rotation angle θ of the Z axis is 0°, and the initial value is 0°. The helical lines on the same side of all the gear teeth of the upper gear and the lower gear are measured by the gear measuring machine. The number of gear teeth, module, pressure angle, helix angle and rotation angle are input into the gear measuring machine, and the gear measuring machine is started. At this time, the gear measuring machine calculates the gear pitch circle size according to the measuring machine program, and the probe is placed exactly on the pitch circle position of the tooth surface according to the rotation angle.

[0043] The starting angle of the first tooth helix is ​​determined by the following formula:

[0044] θ=Z×tanβ b / r

[0045] Where:

[0046] Z—Z-axis coordinate value of the starting point.

[0047] β b —Base circle helix angle.

[0048] r—pitch circle radius.

[0049] The starting angle of the helix of the rear-stage teeth is calculated by the number of teeth.

[0050] According to the intersection of the extended line of the least squares midline of the gear tooth helix line as the tooth surface vertex, it is known that there are a total of vertices on the same side of the tooth surface, and their theoretical positions should be distributed on the symmetry center plane. However, due to the existence of manufacturing errors, the axial positions of these vertices do not fall on the symmetry center plane, and their deviation distance from the symmetry center plane is the alignment deviation, recorded as f Ai , i represents the number of teeth, i ranges from 1 to the total number of teeth, see Figure 5 .

[0051] The alignment difference between adjacent teeth is calculated by the following formula: the maximum absolute value of the algebraic difference between adjacent gear teeth is taken and recorded as f Au :

[0052] f Au =max|f Ai+1 -f Ai

[0053] The algebraic difference between the maximum and minimum values ​​of the symmetry deviation of all teeth of the herringbone gear is calculated by the following formula, which is taken as the total alignment deviation of the herringbone gear and recorded as F A :

[0054] F A =max(f Ai )-min(f Ai )

[0055] The arithmetic mean of the alignment deviations of all adjacent teeth is calculated by the following formula as the symmetry deviation of the herringbone gear, denoted as f AS :

[0056]

[0057] Due to the difference in alignment of adjacent teeth f Au It affects the axial vibration and working noise of the gear, which reflects the situation of the single pitch limit deviation. Therefore, the evaluation result should be consistent with the single pitch limit deviation accuracy level of the existing design parameter standard.

[0058] Total deviation of herringbone gear alignment F A It affects the rotation stability of the gear and the vibration of the whole machine. In this embodiment, the evaluation result is no more than 0.02.

[0059] Symmetry deviation of herringbone gear fAS It reflects the cumulative pitch deviation of all gear teeth of the entire gear, so the accuracy grade result should be consistent with the cumulative pitch deviation accuracy grade of the existing design parameter standard.

[0060] See Figure 6 In the embodiment shown, after testing by this solution, it can be seen that the alignment deviation is -0.0305-0.0084mm; the total alignment deviation F A is 0.0221 mm, which occurs between the 7th and 15th teeth; the alignment difference f of adjacent teeth Au is 0.0125mm, which occurs between the 14th and 15th teeth; the symmetry deviation of the herringbone gear f AS It is -0.0230mm, which meets the requirements of the design drawings.

Claims

1. A method for evaluating the symmetry of a herringbone gear, characterized in that: The method comprises the following steps: S1. Install the herringbone gear coaxially on the rotary shaft of the gear measuring machine operating table; S2. Determine the symmetry center plane using the upper and lower end faces of the outer sides of the left and right gear teeth of the herringbone gear as the measurement reference, and establish a coordinate system; S3. Select a probe with a suitable head diameter. The size of the probe head must be sufficient to extend into the pitch circle position of the tooth groove; S4, inputting the parameters of the herringbone gear into a gear measuring machine, and measuring the same-side helical lines of all the gear teeth of the upper gear and the lower gear by the gear measuring machine; S5. Calculate the deviation distance of all tooth surface vertices on the same side relative to the symmetric center plane, which is recorded as the alignment deviation f Ai , i represents the number of teeth, and the range of i is from 1 to the total number of teeth; S6. Calculate the maximum absolute value of the algebraic difference between the alignment of adjacent gear teeth, which is recorded as the alignment difference f between adjacent gear teeth. Au ,Pick Au :f Au =max|f Ai+1 -f Ai |; S7. Calculate the algebraic difference between the maximum and minimum values ​​of the symmetry deviation of all teeth of the herringbone gear, and record it as the total alignment deviation of the herringbone gear F. A :F A =max(f Ai )-min(f Ai ); S8. Calculate the arithmetic mean of all adjacent tooth alignment deviations, recorded as the herringbone gear symmetry deviation f AS : S9. Evaluate the herringbone gears based on various calculation results.

2. The herringbone gear symmetry evaluation method according to claim 1, characterized in that: In S1, the lower shaft hole of the herringbone gear is assembled on the lower center of the center tooling or on the part fixing fixture.

3. The herringbone gear symmetry evaluation method according to claim 2, characterized in that: Turn the rotating platform of the gear measuring machine and use a micrometer to align the upper and lower journals of the herringbone gear.

4. The herringbone gear symmetry evaluation method according to claim 1, characterized in that: In S2, the symmetry center plane is determined by measuring the tooth width of the upper gear and the lower gear, and half the tooth width G1 of the upper gear and half the tooth width G3 of the lower gear are calculated. The upper gear end face or the lower gear end face of the herringbone gear is used as the measurement reference A, and the outer end face distance of the herringbone gear is obtained by measurement, and the distance G2 from the measurement reference A to half the tooth width of the gear on the other side is determined.

5. The herringbone gear symmetry evaluation method according to claim 4, characterized in that: The rotation axis is taken as the Z axis of the coordinate system, and the center plane of symmetry is taken as the plane where the XY axis is located.

6. The method for evaluating the symmetry of herringbone gears according to claim 1, characterized in that: In S4, the parameters of the herringbone gear include the number of gear teeth, module, pressure angle, helix angle and rotation angle. The gear measuring machine calculates the size of the gear pitch circle and makes the probe touch the pitch circle position of the tooth surface according to the rotation angle.

7. The method for evaluating the symmetry of herringbone gears according to claim 6, characterized in that: The starting angle of the first tooth helix is ​​determined by the following formula: θ=Z×tanβ b / r Z is the Z-axis coordinate value of the starting point, β b is the base circle helix angle, and r is the pitch circle radius.

8. The method for evaluating the symmetry of herringbone gears according to claim 7, characterized in that: The starting angle of the helix of the rear-stage teeth is calculated by the number of teeth.

9. The method for evaluating the symmetry of herringbone gears according to claim 1, characterized in that: Adjacent teeth alignment difference f Au Symmetry deviation f of herringbone gear AS It should be consistent with the single pitch limit deviation accuracy level of the existing design parameter standard; Total deviation of herringbone gear alignment F A Not greater than the experience value.

10. The method for evaluating the symmetry of herringbone gears according to claim 9, characterized in that: Total deviation of herringbone gear alignment F A Not greater than the empirical value of 0.02.

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