Main shaft rotation error multi-probe measurement method based on standard flat plate

Abstract

The invention belongs to the technical field of precision mechanical measurement, provides a main shaft rotation error multi-probe measurement method based on a standard flat plate, and solves the technical problem that an existing method cannot measure angular motion errors or is complex in measurement steps. A standard flat plate and a displacement sensor are built on a measured main shaft, initial displacement signals are continuously collected in real time and transmitted to a signal collecting and processing system, and weighted summation is carried out on the initial displacement signals to construct a weighting function; fourier transform is carried out on the weighting function, and a Fourier coefficient of the sum of a residual surface shape curve and residual pure axial motion errors at the radius R of the standard flat plate is obtained through arrangement; therefore, the axial motion errors of the X-axis and the Y-axis of the measured main shaft at the radius R and the angular motion errors of the measured main shaft rotating around the X-axis and the Y-axis respectively can be calculated, the measurement steps are simple, and the cost is low.

Description

Technical Field

[0001] The invention belongs to the technical field of precision mechanical measurement. Background Art

[0002] In different industrial sites and laboratories, for rotating component spindles, such as machine tool electric spindles or rotary table spindles, the spindle, as an important forming moving component, its rotation error will significantly affect the machining accuracy of precision machining equipment or the detection accuracy of precision measuring instruments, generally resulting in reduced machining accuracy of machine tools and increased measurement uncertainty of instruments such as profilers. Therefore, during the development process or before such rotating components are put into use, the spindle rotation error must be measured to evaluate their performance indicators.

[0003] The existing spindle rotation error measurement method requires the use of a high-precision single-ball standard rod with a roundness of less than 50 nanometers. Limited by domestic processing and manufacturing capabilities, most single-ball standard rods of this precision rely on imports, which are not only expensive, but also have a long procurement cycle. If they are slightly scratched during use, they are difficult to repair and are basically scrapped. In addition, the single-ball standard rod cannot measure the angular motion error. Although the double-ball standard rod can measure the angular motion error, the double-ball standard rod has more eccentricity adjustment steps and is more difficult to operate, resulting in a longer measurement time. Summary of the invention

[0004] In view of the technical problems that the existing measurement methods cannot measure angular motion errors or the measurement steps are complicated and the measurement efficiency is low, the present invention proposes a multi-probe measurement method for spindle rotation errors based on a standard plate.

[0005] A multi-probe measurement method for spindle rotation error based on a standard plate comprises the following steps:

[0006] Step 1: Build a standard plate and displacement sensor and collect the initial displacement signal:

[0007] like Figure 1 As shown, a standard plate 2 is fixedly installed on the spindle 1 to be measured;

[0008] Four displacement sensors 3 are non-contactly installed above the end surface of the standard plate 2, and the axes of the displacement sensors are perpendicular to the standard plate. The projections of the first displacement sensor probe 31, the second displacement sensor probe 32, and the third displacement sensor probe 33 on the standard plate 2 are located on the same virtual circle with a radius of R, and the center of the virtual circle coincides with the rotation center of the measured spindle. The projection of the fourth displacement sensor probe 34 on the standard plate is located at the rotation center of the measured spindle; and the line connecting the projection of the first displacement sensor probe 31 and the center of the virtual circle is defined as the X-axis, the angle between the line connecting the projection of the second displacement sensor probe 32 and the center of the virtual circle and the X-axis is φ, and the angle between the line connecting the projection of the third displacement sensor probe 33 and the center of the virtual circle and the X-axis is ψ;

[0009] The spindle 1 to be measured is driven to rotate at a constant speed, and four displacement sensors continuously and in real time collect multi-turn displacement signals and transmit them to the signal acquisition and processing system 4. The multi-turn displacement signals collected by the first displacement sensor probe 31, the second displacement sensor probe 32, the third displacement sensor probe 33, and the fourth displacement sensor probe 34 are respectively recorded as m1(θ), m2(θ), m3(θ), and m4(θ) after filtering out the first-order harmonic and DC components. m1(θ)=P(θ)+z(θ)+x(θ),

[0010]

[0011] m3(θ)=P(θ-ψ)+z(θ-ψ)+x(θ)cosψ+y(θ)sinψ,

[0012] m4(θ)=z(θ),

[0013] Wherein, θ is the rotation angle of the measured spindle, P(θ) is the residual surface curve at the radius R of the virtual circle on the standard plate, z(θ) is the residual pure axial motion error of the rotation center of the measured spindle, x(θ) is the axial motion error at the radius R on the X-axis of the measured spindle, and y(θ) is the axial motion error at the radius R on the Y-axis of the measured spindle;

[0014] Step 2: Figure 2 As shown, the data is post-processed to calculate the rotation error:

[0015] 21. Perform weighted summation on m1(θ), m2(θ), and m3(θ) to construct the weight function M(θ). Perform Fourier transform on M(θ) and sort it out to obtain the Fourier coefficient of the sum of the residual surface curve and the residual pure axial motion error at the virtual circumference radius R of the standard plate. Perform inverse Fourier transform on the coefficient to obtain the sum of the residual surface curve and the residual pure axial motion error at the virtual circumference radius R of the standard plate.

[0016]

[0017] Among them, m is the highest Fourier order calculated, j is the imaginary part operator, k is the Fourier order, P(jk) and z(jk) are the Fourier coefficients of the residual surface shape and residual pure axial motion error of the standard plate respectively;

[0018] 22. After filtering out the first-order harmonic and DC components, the displacement signal of the fourth displacement sensor probe 34 is equivalent to the residual pure axial motion error of the measured spindle rotation center. Subtract it from the above calculation result to obtain the residual surface curve at the radius R of the standard plate.

[0019]

[0020] The residual pure axial motion error z(θ) of the measured spindle rotation center is:

[0021]

[0022] 23. Calculate the axial motion error at radius R on the X-axis and Y-axis of the measured spindle:

[0023] x(θ)=m1(θ)-P(θ)-z(θ),

[0024] or

[0025] 24. Calculate the angular motion error of the measured spindle rotating around the X-axis and Y-axis respectively:

[0026]

[0027] 25. Calculate the average value of the multi-turn measurement results to obtain the pure axial motion synchronization error z s (θ) is:

[0028]

[0029] The angular motion synchronization error T of the measured spindle rotating around the X-axis and Y-axis respectively xs (θ), T ys (θ) is:

[0030]

[0031] Where n is the total number of revolutions measured, i represents the i-th revolution measurement, and the subscript s represents the synchronization error;

[0032] 26. Subtract the synchronization error from the measurement result of any revolution to obtain the asynchronous error z of pure axial motion of any revolution a (θ) is:

[0033] z a (θ) = z i (θ)-zs (θ),

[0034] The angular motion asynchronous error T of the measured spindle rotating around the X-axis and Y-axis respectively xa (θ), T ya (θ) is:

[0035] T xa (θ) = T xi (θ)-T xs (θ),

[0036] T ya (θ) = T yi (θ)-T ys (θ),

[0037] Where n is the total number of revolutions measured, i represents the i-th revolution measurement, and the subscript a represents the asynchronous error.

[0038] Technical effects:

[0039] The present invention proposes a multi-probe measurement method for spindle rotation error based on a standard plate. The method uses a standard plate and a displacement sensor for measurement, and performs data post-processing on the collected displacement signal to obtain the spindle rotation error. Compared with the existing spindle error measurement method:

[0040] 1. Simple operation. The position of the standard plate remains unchanged during a continuous measurement. The initial installation position can be within the measurement area of ​​the displacement sensor. There is no need to adjust the eccentricity of the installation position of the standard plate. The measurement process is fast and efficient.

[0041] 2. The measurement method gets rid of the dependence on imported high-precision single-ball standard rods and double-ball standard rods, and has low cost. The measurement can be completed by only using a standard plate processed by a single-point diamond lathe or optical milling machine and a high-precision displacement sensor. The occasional scratch on the standard plate can also be quickly repaired by a single-point diamond lathe or optical milling machine.

[0042] 3. The axial motion error and angular motion error can be measured simultaneously. The surface shape of the standard plate can be separated and the components of the main axis error can be calculated through only one continuous measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Schematic diagram of the measurement principle in step 1 of the present invention.

[0044] Figure 2 This is the overall flow chart of step 2 of the present invention. DETAILED DESCRIPTION

[0045] In order to make the technical solution of the present invention clearer, the technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0046] The specific calculation process of step 21 is as follows:

[0047] Perform weighted summation on m1(θ), m2(θ), and m3(θ) to construct the weight function M(θ):

[0048]

[0049] In the formula, a and b are weight coefficients;

[0050] Perform Fourier transform on the weight function M(θ) and sort it out to get:

[0051]

[0052] Where j is the imaginary operator, k is the Fourier order, P(jk) and z(jk) are the Fourier coefficients of the residual surface shape and residual pure axial motion error of the standard plate, respectively;

[0053] Perform inverse Fourier transform on the above Fourier coefficients to obtain the sum of the residual surface shape of the standard plate and the residual pure axial motion error.

[0054] Where m is the highest Fourier order calculated.

[0055] The standard plate 2 is made of aluminum alloy and is processed by a single-point diamond lathe, and its processing surface accuracy is below 50 nanometers; the displacement sensor 3 adopts a capacitive displacement sensor, and its measurement accuracy is at the nanometer level.

[0056] Furthermore, the material of the standard plate 2 can also be microcrystalline glass, which is processed by an optical milling machine, and its processing surface accuracy is below 50 nanometers; the displacement sensor 3 uses a laser displacement sensor, and its measurement accuracy is at the nanometer level.

[0057] The contents not described in detail in this specification belong to the prior art known to those skilled in the art. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A multi-probe measurement method for spindle rotation error based on a standard plate, characterized in that: The steps include: Step 1: Build a standard plate and displacement sensor and collect the initial displacement signal: A standard plate (2) is fixedly mounted on the spindle (1) to be measured; Four displacement sensors (3) are non-contactly mounted above the end surface of the standard plate (2), the axes of the displacement sensors are perpendicular to the standard plate, the projections of the first displacement sensor probe (31), the second displacement sensor probe (32), and the third displacement sensor probe (33) on the standard plate (2) are located on the same virtual circle with a radius of R, the center of the virtual circle coincides with the rotation center of the spindle to be measured, and the projection of the fourth displacement sensor probe (34) on the standard plate is located at the rotation center of the spindle to be measured; and the line connecting the projection of the first displacement sensor probe (31) and the center of the virtual circle extending outward is defined as the X-axis, and the angle between the line connecting the projection of the second displacement sensor probe (32) and the center of the virtual circle and the X-axis is defined as The angle between the projection of the third displacement sensor probe (33) and the line connecting the center of the virtual circle and the X-axis is ψ; The spindle (1) to be measured is driven to rotate at a constant speed, and four displacement sensors continuously and in real time collect multi-turn displacement signals and transmit them to a signal collection and processing system (4). The multi-turn displacement signals collected by the first displacement sensor probe (31), the second displacement sensor probe (32), the third displacement sensor probe (33), and the fourth displacement sensor probe (34) are recorded as m1(θ), m2(θ), m3(θ), and m4(θ) respectively after filtering out the first-order harmonic and direct current components. m1(θ)=P(θ)+z(θ)+x(θ), m3(θ)=P(θ-ψ)+z(θ-ψ)+x(θ)cosψ+y(θ)sinψ, m4(θ)=z(θ), Wherein, θ is the rotation angle of the measured spindle, P(θ) is the residual surface curve at the radius R of the virtual circle on the standard plate, z(θ) is the residual pure axial motion error of the rotation center of the measured spindle, x(θ) is the axial motion error at the radius R on the X-axis of the measured spindle, and y(θ) is the axial motion error at the radius R on the Y-axis of the measured spindle; Step 2: Data post-processing to calculate rotation error:

21. Perform weighted summation on m1(θ), m2(θ), and m3(θ) to construct the weight function M(θ). Perform Fourier transform on M(θ) and sort it out to obtain the Fourier coefficient of the sum of the residual surface curve and the residual pure axial motion error at the virtual circumference radius R of the standard plate. Perform inverse Fourier transform on the coefficient to obtain the sum of the residual surface curve and the residual pure axial motion error at the virtual circumference radius R of the standard plate. Among them, m is the highest Fourier order calculated, j is the imaginary part operator, k is the Fourier order, P(jk) and z(jk) are the Fourier coefficients of the residual surface shape and residual pure axial motion error of the standard plate respectively; 22. The displacement signal of the fourth displacement sensor probe (34) is equivalent to the residual pure axial motion error of the rotation center of the measured spindle after filtering out the first-order harmonic and DC components. It is subtracted from the above calculation result to obtain the residual surface curve at the radius R of the standard plate. The residual pure axial motion error z(θ) of the measured spindle rotation center is:

23. Calculate the axial motion error at radius R on the X-axis and Y-axis of the measured spindle: x(θ)=m1(θ)-P(θ)-z(θ), or 24. Calculate the angular motion error of the measured spindle rotating around the X-axis and Y-axis respectively:

25. Calculate the average value of the multi-turn measurement results to obtain the pure axial motion synchronization error z s (θ) is: The angular motion synchronization error T of the measured spindle rotating around the X-axis and Y-axis respectively xs (θ), T ys (θ) is: Where n is the total number of revolutions measured, i represents the i-th revolution measurement, and the subscript s represents the synchronization error; 26. Subtract the synchronization error from the measurement result of any revolution to obtain the asynchronous error z of pure axial motion of any revolution a (θ) is: With a (θ)=z i (θ)-z s (θ), The angular motion asynchronous error T of the measured spindle rotating around the X-axis and Y-axis respectively xa (θ), T ya (θ) is: T xa (θ)=T xi (θ)-T xs (i), T ya (θ)=T yi (θ)-T ys (i), Where n is the total number of revolutions measured, i represents the i-th revolution measurement, and the subscript a represents the asynchronous error.

2. The multi-probe measurement method for spindle rotation error based on a standard plate according to claim 1 is characterized in that: The specific calculation process of step 21 is as follows: Perform weighted summation on m1(θ), m2(θ), and m3(θ) to construct the weight function M(θ): In the formula, a and b are weight coefficients; Perform Fourier transform on the weight function M(θ) and sort it out to get: Where j is the imaginary operator, k is the Fourier order, P(jk) and z(jk) are the Fourier coefficients of the residual surface shape and residual pure axial motion error of the standard plate, respectively; Perform inverse Fourier transform on the above Fourier coefficients to obtain the sum of the residual surface shape of the standard plate and the residual pure axial motion error. Where m is the highest Fourier order calculated.

3. The multi-probe measurement method for spindle rotation error based on a standard plate according to claim 1 is characterized in that: The standard plate (2) is made of aluminum alloy and is machined by a single-point diamond lathe, with a machining surface accuracy of less than 50 nanometers; the displacement sensor (3) adopts a capacitive displacement sensor, with a measurement accuracy of nanometers.

4. The multi-probe measurement method for spindle rotation error based on a standard plate according to claim 1 is characterized in that: The standard plate (2) is made of microcrystalline glass and is processed by an optical milling machine, with a processing surface accuracy of less than 50 nanometers; the displacement sensor (3) adopts a laser displacement sensor, and its measurement accuracy is at the nanometer level.

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