A machining process method for precision holes of a shell assembly

Abstract

The application relates to a machining process method for a precision hole of a shell assembly, and specifically comprises the following steps: selecting a test piece, adopting a DOE method to process the test piece, obtaining the polar angle error of a machine tool, adopting a three-coordinate to perform actual center processing coordinate fitting, obtaining the eccentricity value (X1, Y1) of an actual alignment circle, determining an alignment method based on the obtained coordinate, eliminating processing errors, and completing precision hole processing closest to a base after alignment. The application adopts a mathematical calculation combined with an elliptical alignment method based on the DOE method to obtain an optimal processing scheme under multiple working conditions, so that the position degree of the precision hole of the part shell assembly is controlled within a tolerance range under a free state.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of precision machining, and particularly relates to a machining process method for a precision hole of an L-shaped shell assembly. BACKGROUND

[0002] In a transmission structure, the external structural member bearing gears has a high precision requirement for the positions on both sides. At present, in a harsh machining environment, the precision equipment and the commonly used machining ideas are often affected by error accumulation, leading to a situation that the tolerance is difficult to guarantee during machining, and therefore the machining difficulty and the machining cost of the part are relatively large. SUMMARY

[0003] In view of the deficiencies in the prior art, the present application provides a machining process method for a precision hole of a shell assembly, which obtains the best machining scheme under multiple working conditions based on the DOE method and the method of mathematical calculation combined with ellipse alignment, so as to ensure that the position degree of the precision hole of the part shell assembly is controlled within the tolerance range in the free state.

[0004] A machining process method for a precision hole of a shell assembly, specifically comprising the following steps:

[0005] Step one: select a test piece, and use the DOE method to process the test piece on a machine tool to obtain the polar error of the machine tool;

[0006] Step two: place the part in a three-coordinate system, wherein the precision hole to be machined, i.e. the vertical part of the L-shaped part, is symmetrical relative to the X-Z measurement plane of the three-coordinate system; use the three-coordinate to perform actual center processing coordinate fitting to obtain the eccentricity data (X1, Y1) of the actual alignment circle;

[0007] Step three: determine the alignment method based on the coordinates (X1, Y1) obtained in step two to eliminate the machining error;

[0008] Step four: after alignment, complete the machining of the precision hole closest to the base, and then sequentially machine the precision holes outward from the precision hole closest to the base.

[0009] In step three, the specific machining scheme is as follows:

[0010] 1: if Y1<0,

[0011] 1.1: X1<0, at this time, the eccentricity of the X-axis, i.e. the horizontal axis of the ellipse, is Arcsin(X1 / r), and the position degree is

[0012] A1=2×{X1*(X1+R2)÷r+Y1}+0.004 (1)

[0013] A2 = 2 x {X1*(X1+R1) ÷ r + Y1} + 0.004 (2)

[0014] Wherein, the value 0.004 in the formula (1) and formula (2) is the polar angle deviation obtained by using the limit method in step one; A1, A2 adopt absolute value;

[0015] At this time, the Y-axis negative eccentricity ellipse alignment method is used, and the Y-axis point offset is

[0016] -{Y1+X1*(X1+R1) ÷ r + 0.004} (3)

[0017] 1.2: X1≥0, at this time, the eccentricity generated by the horizontal axis is -Arcsin(X1 / r), and the position degree A1, A2 is

[0018] A1 = 2 x {Y1-X1*(X1+R2) ÷ r} + 0.004 (4)

[0019] A2 = 2 x {Y1-X1*(X1+R1) ÷ r} + 0.004 (5)

[0020] Wherein, the value 0.004 in the formula (4) and formula (5) is the polar angle deviation obtained by using the limit method in step one; At this time, the machining scheme needs to be determined, and the precise hole closest to the base is used as the determination basis:

[0021] 1.2.1: If Y1>X1*(X1+R2) ÷ r, at this time, the Y-axis positive eccentricity ellipse alignment method is used, and the Y-axis point offset is

[0022] -{Y1-X1*(X1+R2) ÷ r + 0.004} (6)

[0023] 1.2.2 If Y1=X1*(X1+R2) ÷ r, at this time, the conventional alignment method is used;

[0024] 1.2.3 If Y1X1*(X1+R2) ÷ r, at this time, the Y-axis negative eccentricity ellipse alignment method is used, and the Y-axis point offset is

[0025] {Y1-X1*(X1+R2) ÷ r + 0.004} (7)

[0026] 2: If Y1>0,

[0027] 2.1: X1≥0, at this time, the eccentricity generated by the horizontal axis is -Arcsin(X1 / r), and the position degree is

[0028] A1 = 2 x {X1*(X1+R2) ÷ r + Y1} + 0.004 (8)

[0029] A2 = 2 x {X1*(X1+R1)÷r+Y1}+0.004 (9)

[0030] Wherein, the value 0.004 in the formula (8) and formula (9) is the polar angle deviation obtained by using the limit method in step one; A1, A2 adopt absolute value; At this time, the Y-axis positive eccentric ellipse alignment method is used, and the Y-axis point offset is

[0031] -{Y1+X1*(X1+R2)÷r+0.004} (10)

[0032] 2.2: X1 < 0, at this time, the eccentricity generated by the horizontal axis is -Arcsin (X1 / r), and the position degree A1, A2 are

[0033] A1 = 2 x {X1*(X1+R2)÷r+Y1}+0.004 (11)

[0034] A2 = 2 x {X1*(X1+R1)÷r+Y1}+0.004 (12)

[0035] At this time, the processing scheme needs to be determined, and the precise hole closest to the base is used as the determination basis: A1, A2 adopt absolute value;

[0036] 2.2.1: If Y1 > X1*(X1+R2)÷r, at this time, the Y-axis negative eccentric ellipse alignment method is used, and the Y-axis point offset is

[0037] -{Y1+X1*(X1+R2)÷r+0.004} (13)

[0038] 2.2.2: If Y1 = X1*(X1+R2)÷r, at this time, the conventional alignment method is usually used;

[0039] 2.2.3: If Y1 < X1*(X1+R2)÷r, at this time, the Y-axis positive eccentric ellipse alignment method is used, and the Y-axis point offset is

[0040] {Y1+X1*(X1+R2)÷r+0.004} (14).

[0041] In step three, when the unconventional alignment method is used for alignment, the precise holes other than the precise hole closest to the base need to be processed and compensated in subsequent processing.

[0042] When compensating, the numerical value compensation is added in the machine tool coordinate system, and the Z-axis numerical value compensation is

[0043] X1*(X1+R1)÷r-X1*(X1+R2)÷r (15).

[0044] The beneficial effects of this invention are as follows: This invention obtains the process parameters for part machining based on DOE (Design of Effect) experiments, and eliminates machining errors by using vector decomposition based on the formation mechanism of positional accuracy. Based on the DOE method, mathematical calculations combined with elliptic alignment are used to obtain the optimal machining scheme under multiple working conditions, ensuring that the positional accuracy of the precision holes in the part's housing assembly remains within tolerance range under free conditions. Applying this method, the precision holes of this part can be machined to a 100% pass rate; and it can be extended to transmission components with similar structures to achieve qualified machining of precision holes in similar structures. Attached Figure Description

[0045] Figure 1 A front view of a part provided in an embodiment of the present invention;

[0046] Figure 2 Top view of the part provided in the embodiment of the present invention Figure 1 (Where X and Y are coordinate systems in a three-coordinate system, circle 1 is the reference circle of the part, circle 2 is the actual alignment circle of the part, and circle 3 is the angular hole of the part).

[0047] Figure 3 Top view of the part provided in the embodiment of the present invention Figure 2 (Where X and Y are coordinate systems in a three-coordinate system, circle 4 is the precision hole one being machined, and circle 5 is the precision hole two being machined); Detailed Implementation

[0048] To better explain and facilitate understanding of the present invention, the technical solution and effects of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] The main view of the L-shaped part provided in this embodiment is as follows: Figure 1 As shown, it includes two precision holes to be machined; as Figures 2-3 As shown, the part is placed in a coordinate measuring system. The horizontal part of the L-shaped part, i.e., the base, is located in the XY measurement plane of the coordinate measuring system. The precision hole to be machined, i.e., the vertical part of the L-shape, is symmetrical with respect to the XZ measurement plane of the coordinate measuring system. In the figure, circle 1 is the reference circle of the part, circle 2 is the actual alignment circle of the part, circle 3 is the angular hole of the part, and X and Y are the coordinate systems in the coordinate measuring system. Circle 4 is the first precision hole to be machined, and circle 5 is the second precision hole coaxial with circle 4, which is the precision hole closest to the base. R1 and R2 correspond to the distances from the first and second precision holes to the center of the circles, respectively, and are represented by A1 and A2 to indicate their machining positional accuracy, respectively. r is the theoretical radius of the angular hole corresponding to the reference circle. This application provides a machining process method for precision holes in housing components, specifically including the following steps:

[0050] Step one: select a test piece, using DOE method in the machine tool processing, to obtain the polar angle error of the machine tool. Specifically, record the processing data after processing, and perform three coordinate detection. Subtract the measured polar angle value from the theoretical polar angle value of the machine tool to obtain the polar angle error of 0.004.

[0051] The machine tool is a precision boring machine.

[0052] Step two: use three coordinates to fit the actual center processing coordinates of the circle to obtain the eccentricity data (X1, Y1) of the actual centering circle 2, and use the coordinate method to confirm the point position. Specifically:

[0053] Use a three-coordinate measuring machine to select 16 evenly distributed points on the actual centering circle 2 on the base to measure. The least squares method is used to fit the 16 measured points to obtain the fitting contour of the actual centering circle 2. Read the center coordinates of the fitting contour of the actual centering circle 2 in the three-coordinate measuring machine. The center coordinates are the eccentricity data (X1, Y1) of the actual centering circle 2.

[0054] Step three: based on the coordinates (X1, Y1) obtained in step two, determine the centering method to eliminate processing errors:

[0055] 1: if Y1<0,

[0056] 1.1: X1<0, at this time the eccentricity of the X-axis, which is the horizontal axis of the ellipse, is Arcsin(X1 / r), and the position degree is

[0057] A1=2×{X1*(X1+R2)÷r+Y1}+0.004 (1)

[0058] A2=2×{X1*(X1+R1)÷r+Y1}+0.004 (2)

[0059] Wherein, the value 0.004 in formula (1) and formula (2) is the polar angle deviation obtained by using the limit method in step one, that is, the angle offset of 0.004 corresponds to the X-axis error of 0.004; A1, A2 adopt absolute value.

[0060] At this time, the Y-axis negative eccentricity ellipse centering method is used, and the Y-axis point offset is

[0061] -{Y1+X1*(X1+R1)÷r+0.004}(3).

[0062] 1.2: X1≥0, at this time the eccentricity of the horizontal axis is -Arcsin(X1 / r), and the position degrees A1, A2 are

[0063] A1=2×{Y1-X1*(X1+R2)÷r}+0.004 (4)

[0064] A2 = 2 x {Y1 - X1*(X1 + R1) ÷ r} + 0.004 (5)

[0065] Wherein, the value 0.004 in formula (4) and formula (5) is the polar angle deviation obtained by using the limit method in step one, that is, the angle offset of 0.004 corresponds to the X-axis error of 0.004. At this time, the processing scheme needs to be determined. Since the machining difficulty of circle 5, i.e. the second precision hole, is affected by the structure of the part, the tool suspension is long, the machining precision is lower than that of circle 4, and the measurement is poor, the best is directly guaranteed, so the precision hole closest to the base, i.e. the second precision hole of circle 5, is used as the basis for determination. A1 and A2 are absolute values.

[0066] 1.2.1: If Y1 > X1*(X1 + R2) ÷ r, at this time, the Y-axis positive eccentric ellipse centering method is used, and the Y-axis offset to the point is

[0067] -{Y1 - X1*(X1 + R2) ÷ r + 0.004} (6).

[0068] 1.2.2: If Y1 = X1*(X1 + R2) ÷ r, at this time, the conventional centering method is used.

[0069] 1.2.3: If Y1 < X1*(X1 + R2) ÷ r, at this time, the Y-axis eccentric ellipse centering method is used, and the Y-axis offset to the point is

[0070] {Y1 - X1*(X1 + R2) ÷ r + 0.004} (7).

[0071] When the unconventional centering method is used for centering, the circle 4, i.e. the first precision hole, needs to be processed and compensated in subsequent processing.

[0072] 2: If Y1 > 0,

[0073] 2.1: X1 ≥ 0, at this time, the eccentricity generated by the horizontal axis is -Arcsin(X1 / r), and the position degree at this time is

[0074] A1 = 2 x {X1*(X1 + R2) ÷ r + Y1} + 0.004 (8)

[0075] A2 = 2 x {X1*(X1 + R1) ÷ r + Y1} + 0.004 (9)

[0076] Wherein, the value 0.004 in formula (8) and formula (9) is the polar angle deviation obtained by using the limit method in step one, that is, the angle offset of 0.004 corresponds to the X-axis error of 0.004; at this time, the Y-axis positive eccentric ellipse centering method is used, and the Y-axis offset to the point is

[0077] -{Y1+X1*(X1+R2)÷r+0.004}(10)A1 and A2 use absolute values.

[0078] 2.2: When X < 0, the eccentricity of the horizontal axis is -Arcsin(X1 / r), and the positional degrees A1 and A2 are...

[0079] A1=2×{X1*(X1+R2)÷r+Y1}+0.004 (11)

[0080] A2=2×{X1*(X1+R1)÷r+Y1}+0.004 (12)

[0081] At this point, a processing scheme needs to be determined, using circle 5, i.e., precision hole 2, as the basis for determination: A1 and A2 use absolute values.

[0082] 2.2.1: If Y1 > X1*(X1+R2)÷r, then the negative Y-axis elliptical eccentricity correction method is used, and the Y-axis offset relative to the point is...

[0083] -{Y1+X1*(X1+R2)÷r+0.004}(13)

[0084] 2.2.2: If Y1 = X1*(X1+R2)÷r, the conventional method of finding the correct value is commonly used.

[0085] 2.2.3: If Y1 < X1*(X1+R2)÷r, then the positive Y-axis elliptical eccentricity alignment method is used, and the Y-axis offset relative to the point is...

[0086] {Y1+X1*(X1+R2)÷r+0.004}(14)

[0087] When an unconventional alignment method is used for alignment, the precision hole 1 (circle 4) is compensated for during subsequent machining.

[0088] Step 4: After alignment, clamp the workpiece on a precision boring machine for machining. First, run the machine tool's self-calibration program 15 times. Determine the machine tool's zero-point drift by observing the fluctuations in the X, Y, and Z values ​​in the coordinate system. If there are no issues, complete the machining of circle 5 (precision hole two), and then proceed with the machining of circle 4 (precision hole one). If circle 4 and precision hole one require program compensation, add numerical compensation in the machine tool coordinate system during the machining of circle 4 (precision hole one). The Z-axis numerical compensation is as follows:

[0089] X1*(X1+R1)÷r-X1*(X1+R2)÷r(15)

[0090] This ensures that the holes in the parts are machined to the required standard.

[0091] Example 1

[0092] In this embodiment, the eccentricity data of the actual alignment circle 2 (X1, Y1) = (-0.01, -0.02), R1 = 175, R2 = 108.7, r = 123, at this time,

[0093] A1 = ABS (2 * (-0.01 * (-0.01 + 108.7) / 123 + (-0.02) + 0.004) ) = 0.0496

[0094] A2 = ABS (2 * (-0.01 * (-0.01 + 175) / 123 + (-0.02) + 0.004) ) = 0.0764

[0095] The Y-axis positive circle eccentricity alignment method is adopted.

[0096] The Y-axis point offset is:

[0097] - (-0.02 - 0.01 * (-0.01 + 108.7) / 123 + 0.004) = 0.024

[0098] The Y-axis value compensation is:

[0099] (-0.01) * (-0.01 + 108.7) / 123 - (-0.01) * (-0.01 + 175.2) / 123 = 0.0054.

[0100] Example 2

[0101] In this embodiment, the eccentricity data of the actual alignment circle 2 (X1, Y1) = (0.01, -0.02), R1 = 175, R2 = 108.7, r = 123, at this time,

[0102] A1 = ABS (2 * (0.01 * (0.01 + 108.7) / 123 + (-0.02) + 0.004) ) = 0.0143

[0103] A2 = ABS (2 * (0.01 * (0.01 + 175) / 123 + (-0.02) + 0.004) ) = 0.0035

[0104] The alignment method is determined: 0.02 > 0.008, at this time, the Y-axis positive circle eccentricity alignment method is adopted.

[0105] The Y-axis point offset is:

[0106] - (-0.02 + 0.01 * (0.01 + 108.7) / 123 + 0.004) = 0.007

[0107] The Y-axis value compensation is:

[0108] (0.01)*(0.01+108.7) / 123-0.01*(0.01+175.2) / 123=-0.0054.

[0109] Example 3

[0110] In this embodiment, the actual centering data of the circle 2 (X1, Y1) = (-0.01, 0.02), R1 = 175, R2 = 108.7, r = 123, at this time,

[0111] A1 = ABS (2 * (-0.01 * (-0.01 + 108.7) / 123 + (0.02) + 0.004)) = 0.0303

[0112] A2 = ABS (2 * (-0.01 * (-0.01 + 175) / 123 + (0.02) + 0.004)) = 0.0195

[0113] The centering method is determined: 0.02 > 0.008, at this time, the Y-axis negative circle eccentric centering method is adopted;

[0114] The Y-axis offset to the point is:

[0115] - (-0.02 + 0.01 * (0.01 + 108.7) / 123 + 0.004) = -0.015

[0116] The Y-axis numerical compensation is:

[0117] (0.01)*(0.01+108.7) / 123-0.01*(0.01+175.2) / 123=-0.0054.

[0118] Example 4

[0119] In this embodiment, the actual centering data of the circle 2 (X1, Y1) = (0.01, 0.02), R1 = 175, R2 = 108.7, r = 123, at this time,

[0120] A1 = ABS (2 * (0.01 * (0.01 + 108.7) / 123 + (0.02) + 0.004)) = 0.0656

[0121] A2 = ABS (2 * (0.01 * (0.01 + 175) / 123 + (0.02) + 0.004)) = 0.0765

[0122] The Y-axis negative circle eccentric centering method is adopted;

[0123] The Y-axis offset to the point is:

[0124] - (0.02 + 0.01 * (0.01 + 108.7) / 123 + 0.004) = -0.032

[0125] Y axis numerical compensation is:

[0126] (0.01) * (0.01 + 108.7) / 123 - 0.01 * (0.01 + 175.2) / 123 = -0.0054.

Claims

1. A process method for machining precision holes in a housing assembly, comprising: Specifically comprising the following steps: Step one: select a test piece, using the DOE method on the machine tool to process the test piece, and obtain the polar angle error of the machine tool; Step two: place the part in the three coordinate system, wherein the vertical part of the L-shaped precision hole to be machined is symmetrical relative to the X-Z measurement plane of the three coordinate system; use three coordinates to perform actual center fitting, and obtain the eccentricity data (X1, Y1) of the actual alignment circle; Step three: based on the coordinates (X1, Y1) obtained in step two, determine the alignment method to eliminate the machining error; Step four: after alignment, the precision hole closest to the base is machined, and then the precision holes are machined outward from the precision hole closest to the base; In step three, the specific machining scheme is: 1 : if time, 1.1: At this time, the eccentricity generated by the X-axis, i.e. the horizontal axis of the ellipse, is At this time, the position degree is （1） （2） In formula (1) and formula (2), the value 0.004 is the polar angle deviation obtained by using the limit method in step one; A1 and A2 are absolute values; Wherein, R1 is the distance from the machined precision hole one to the center, R2 is the distance from the machined precision hole two to the center, and r is the theoretical radius of the angular hole corresponding to the reference circle of the part; At this time, the Y-axis negative eccentricity ellipse alignment method is used, and the Y-axis point offset is （3） 1.2: At this time, the eccentricity generated by the horizontal axis is At this time, the position degree A1, A2 is （4） （5） In formula (4) and formula (5), the value 0.004 is the polar angle deviation obtained by using the limit method in step one; at this time, the machining scheme needs to be determined, and the precision hole closest to the base is used as the basis for determination: 1.2.1: If At this time, the Y-axis positive direction ellipse eccentricity alignment method is adopted, and the Y-axis point offset is （6） 1.2.2 If a conventional alignment method is used at this time; 1.2.3 If At this time, the Y-axis negative eccentricity alignment method is used, and the Y-axis offset is （7） 2: if time, 2.1: At this time, the eccentricity generated by the horizontal axis is At this time, the position degree is （8） （9） In formula (8) and formula (9), the value 0.004 is the polar angle deviation obtained by using the limit method in step one; A1 and A2 are absolute values; at this time, the Y-axis positive eccentricity ellipse alignment method is used, and the Y-axis point offset is （10） 2.2: At this time, the eccentricity generated by the horizontal axis is At this time, the position degree A1, A2 is （11） （12） At this time, the machining scheme needs to be determined, and the precision hole closest to the base is used as the basis for determination; A1 and A2 are absolute values; 2.2.1: If At this time, the Y-axis negative eccentricity alignment method is used, and the Y-axis offset is （13） 2.2.2: If At this time, the conventional alignment method is usually used; 2.2.3: If At this time, the Y-axis positive direction ellipse eccentricity alignment method is adopted, and the Y-axis point offset is （14）。 2. The process for machining a precision hole in a housing assembly of claim 1, wherein: In step three, when using the unconventional alignment method for alignment, the precision holes other than the precision hole closest to the base need to be machined and compensated in subsequent machining.

3. The process for machining a precision hole in a housing assembly of claim 2, wherein: When compensating, add a numerical value compensation in the machine tool coordinate system, and the Z-axis numerical compensation is （15）。

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