A machine tool spindle rotation error detection device and method

Abstract

The application discloses a machine tool spindle rotation error detection device and method, the device comprises a sensor support fixedly installed outside the spindle box, the sensor support is arranged around the spindle box and extends to the machine tool spindle, three first threaded holes located in the first cross section are arranged on the sensor support outside the machine tool spindle, and eddy current sensors are respectively installed in the first threaded holes; one second threaded hole is further arranged on each of the two sides of the sensor support below the first cross section, and laser rotation speed sensors are respectively installed in the second threaded holes; the device further comprises a rotation error collector and a rotation error detection host machine connected with each other, the rotation error collector is used for collecting signals and transmitting signal data to the rotation error detection host machine, and the rotation error detection host machine performs operation processing on the received signal data to obtain and store the rotation error. The application realizes dynamic detection of the spindle rotation error, improves the measurement efficiency and the detection accuracy, and the detection result is more accurate and reliable.

Description

Technical Field

[0001] This invention belongs to the field of machine tool machining accuracy testing technology, and particularly relates to a machine tool spindle rotation error detection device and method. Background Technology

[0002] With the rapid development of the machinery manufacturing industry, the requirements for the machining accuracy of parts are becoming increasingly higher, which in turn places higher demands on the precision of machine tools. As the core component of a machine tool, the rotational error of the spindle directly affects the machining accuracy of the machine tool. Spindle rotational error is one of the main indicators reflecting the dynamic performance and accuracy of a machine tool, therefore, it is necessary to detect the rotational error of the machine tool spindle.

[0003] Traditional methods for testing and processing spindle rotation error include the American LRL unidirectional measurement method and the Czech VUOSO bidirectional measurement method. The former is suitable for testing the radial error of the spindle during workpiece rotation, while the latter is suitable for testing the radial error of the spindle during tool rotation. Both methods operate under no-load or simulated machining conditions, measuring a reference ball (ring) and displaying a circular image of the spindle rotation on the detection system screen. This circular image is then photographed, and the spindle radial error value is read using a roundness template. The advantages of these two methods are that they can display the graphic on-site, providing strong visual feedback. However, their disadvantages include the shape error of the reference ball being transmitted to the test results, and the inability to reflect the cutting load conditions, leading to inaccurate error detection results. Therefore, how to achieve accurate detection of machine tool spindle rotation error is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a machine tool spindle rotation error detection device and method to solve the above-mentioned technical problems.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention discloses a machine tool spindle rotation error detection device, comprising a spindle housing, a machine tool spindle, and a machine tool control box connected together. The spindle housing is installed on the upper end of the machine tool spindle. The device further includes a sensor bracket fixedly installed on the outside of the spindle housing. The sensor bracket is arranged around the spindle housing and extends to the machine tool spindle. Three first threaded holes located in a first cross-section are provided on the sensor bracket outside the machine tool spindle. Eddy current sensors are respectively installed in the three first threaded holes. A second threaded hole is also provided on the upper and lower sides of the sensor bracket outside the machine tool spindle at the lower cross-section. Two of the second threaded holes connect to one of the first threaded holes. The perforations are located on the same side of the same axial section, and laser speed sensors are installed in the two second threaded holes respectively; a single reflector and a multi-reflector are respectively pasted on the machine tool spindle at positions corresponding to the axial positions of the two second threaded holes; the device also includes a rotation error acquisition unit and a rotation error detection host connected inside the machine tool control box. The rotation error acquisition unit is used to acquire laser speed sensor signals and eddy current sensor signals and transmit the signal data to the rotation error detection host. The rotation error detection host is used to control the rotation error acquisition unit, and to process the received signal data to obtain and store the machine tool spindle rotation error.

[0007] Furthermore, the slewing error acquisition unit is internally equipped with a bandpass filter, an AD converter, and a core processor connected in sequence. The core processor is also connected to two counters. The core processor is connected to two laser speed sensors through the two counters to form a laser speed sensor signal acquisition channel. The bandpass filter is connected to three eddy current sensors to form an eddy current sensor signal acquisition channel. The core processor is connected to the slewing error detection host through an Ethernet communication interface.

[0008] Furthermore, the angles of the three first threaded holes in the circumferential direction of the first cross-section are 0°, 83.6°, and 137.2°, respectively.

[0009] Furthermore, the minimum clearance between the three eddy current sensors and the surface of the machine tool spindle is 1.5 mm.

[0010] Furthermore, the distance between the cross-sections containing the two second threaded holes and the first cross-section is not less than 15 mm.

[0011] Furthermore, three third threaded holes are evenly provided on the sensor bracket on the outside of the spindle housing, and the sensor bracket is fixedly connected to the spindle housing by fastening bolts.

[0012] Furthermore, the length of both the single reflector and the multiple reflectors is the same as the circumference of the machine tool spindle surface. Ten reflective strips of equal width are evenly distributed on the multiple reflectors. The single reflector has one reflective strip with the same width as the reflective strips on the multiple reflectors, and the reflective strip on the single reflector is aligned with one of the reflective strips on the multiple reflectors.

[0013] Furthermore, the eddy current sensor has an accuracy of 0.1 μm, and the laser rotation speed sensor has an accuracy of sensing 20,000 pulses per second and outputting a 3V high-level pulse.

[0014] This invention also discloses a method for detecting the rotational error of a machine tool spindle, the method comprising the following steps:

[0015] Step 1: Start the machine tool spindle rotation error detection device. The machine tool spindle rotates, and the laser pulse signal M1 from the laser speed sensor corresponding to multiple reflectors is collected. (The last part, "t," appears to be incomplete and possibly refers to a specific step or step. It doesn't translate directly but can be left as is.) 10 The number of pulses obtained within a time period is N 10 Therefore, the rotation frequency f of the computer tool spindle r And the rotational speed n, and adjust the machine tool spindle to make it run within the range of 30r / min≤n≤300r / min;

[0016] The rotational frequency f of the machine tool spindle r The formula for calculating the rotational speed n is:

[0017] f r =(N 10 / t 10 ) / K (1)

[0018] n = 60 * f r (2)

[0019] In the formula, f r is the rotational frequency of the machine tool spindle, in Hz; K is the number of reflectors in the multi-reflector system; n is the rotational speed of the machine tool spindle, in r / min;

[0020] Step 2: Based on the rotational frequency f of the machine tool spindle r Set the sampling frequency f s The laser pulse signal M2 of the laser speed sensor corresponding to a single reflector is collected, and the spindle rotation error acquisition device is triggered by the M2 signal to sample at a frequency f. s Displacement signals from three eddy current sensors are acquired simultaneously; the sampling frequency is set to f. s =2048*f r ;

[0021] Step 3: The slewing error acquisition unit performs preprocessing on the acquired displacement signal by filtering, analog-to-digital conversion, and data queue assembly, and transmits the preprocessed signal data to the slewing error detection host. The slewing error detection host processes the received signal data to obtain the machine tool spindle slewing error.

[0022] Furthermore, the specific process by which the rotation error detection host processes the received signal data to obtain the machine tool spindle rotation error is as follows:

[0023] First, error separation is performed, and the synchronous sampling frequency f for each displacement signal is set. s =2048*f r That is, 2048 data points are collected per week, and the data points are collected for 4 rotations of the spindle each time, that is, N=8192 data points. The 8192 data points collected each time are divided into 4 segments, and the average of the 4 segments is calculated point by point in sequence to form a new data sequence. Then, the spindle shape error and spindle rotation error are separated.

[0024] The spindle shape error is separated, and a rectangular coordinate system is established with the center of the cross-section circle as the origin. One eddy current sensor is located on the X-axis of the rectangular coordinate system, and the angles between the other two eddy current sensors and the X-axis are β and α, respectively. The displacement signals acquired by the three eddy current sensors are V1, V2, and V3, respectively. Let r(θ) i ) represents the shape error of the machine tool spindle under test, x(θ) i ) and y(θ i The components of the spindle rotation error in the X and Y axes are respectively. The acquired displacement signal is related to the angle θ through which the machine tool spindle rotates relative to the eddy current sensor located on the X-axis. i The relationship between them is:

[0025] V1(θ i ) = r(θ i )+ x(θ i (3)

[0026] V2(θ i ) = r(θ i +β)+ x(θ i cosβ+ y(θ) i sinβ (4)

[0027] V3(θ i ) = r(θ i + α)+ x(θ i cos α + y(θ) i sin α (5)

[0028] In the formula, r(θ) i), x(θ) i ), y(θ) i The calculation process is as follows: First, determine the relationship between θi and the number of sampling points N:

[0029] θ i = 2πi / (N / 4) (6)

[0030] In the formula, i = 1, 2, ..., N / 4, where N is 8192. Weighting coefficients m1, m2, and m3 are then introduced into the displacement signals collected by the three eddy current sensors for weighting processing. The weighted V(θ) is then calculated. i )for:

[0031] V(θi)=m1V1(θ i )+m2V2(θ i )+m3V3(θ i )

[0032] =m1r(θ) i )+m2r(θ i +β)+m3r(θ i +α)+(m1+m2 cosβ+

[0033] m3 cosα)x(θ i )+(m2 sinβ+m3 sinα)y(θ i (7)

[0034] Calculate the components of the spindle rotation error in the X and Y axes, then separate the shape error present in the weighted signal; set the coefficients of the rotation error components in the X and Y axes to 0, that is:

[0035] m1+ m2 cos β+ m3 cos α = 0 (8)

[0036] m2 sin β+ m3 sin α = 0 (9)

[0037] Let the weighting coefficient m1 = 1 for the eddy current sensor located on the X-axis, then the weighting coefficients m2 and m3 are expressed as follows:

[0038] m2 = -sinα / sin(α-β) (10)

[0039] m3 = sinβ / sin(α-β) (11)

[0040] The signal that retains only the spindle shape error is represented as follows:

[0041] V(θ i ) = r(θ i ) + m2 r(θi +β) + m3 r(θ i +α) (12)

[0042] For r(θ) in the above formula i The Fourier transform of the given information is as follows:

[0043] V'(j) = r'(j)·H(j) (13)

[0044] In the formula, V'(j) and r'(j) are respectively V(θ) i ) and r(θ i The Fourier transform result of ), where j is the harmonic order; H(j) is the weight function in the Fourier transform:

[0045] H(j) = 1 + m2e jkβ +m3e jkα

[0046] = 1 -sinα / sin(α-β)e jkβ + sinβ / sin(α-β)e jkα (14)

[0047] Performing an inverse Fourier transform on r'(j) yields r(θ) i ):

[0048]

[0049] In the formula, IFFT() represents performing an inverse Fourier transform on the data sequence within the parentheses;

[0050] From this, the rotational error of the spindle can be obtained, its components x(θ) in the X and Y axes. i ) and y(θ i They are respectively:

[0051] x(θ i ) = s1(θ i )-r(θ i (16)

[0052] y(θ i ) = [s2(θ i )-r(θ i +α)-x(θ i )cosα] / sinα (17)

[0053] Then, the data sequence is plotted into a ring shape. In the ring shape, an inscribed circle O1 and an circumscribed circle O2 are drawn inside and outside the ring shape, respectively. The diameters and radii of the inscribed circle O1 and the circumscribed circle O2 are D1 and D2, and R1 and R2, respectively. The radius of the circumscribed circle R2 is calculated as the spindle shape error, and the difference between the radii of the circumscribed circle and the inscribed circle R2-R1 is calculated as the spindle rotation error.

[0054] The beneficial effects of this invention are as follows: The machine tool spindle rotation error detection device and method described in this invention can detect the machine tool spindle rotation error under no-load or load conditions, realize the dynamic detection of spindle rotation error, and improve the efficiency of machine tool spindle rotation error measurement; and by adopting the dual-speed measurement method, it can obtain more accurate speed and realize the positioning of shaft shape error and rotation error, which greatly improves the accuracy of error detection and the detection results are more accurate and reliable.

[0055] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0056] Figure 1 A schematic diagram of a machine tool spindle rotation error detection device;

[0057] Figure 2 A schematic diagram showing the circumferential positions of the three first threaded holes;

[0058] Figure 3 Schematic diagrams of single and multiple reflectors;

[0059] Figure 4 A schematic diagram showing the separation of machine tool spindle shape error and rotation error;

[0060] Figure 5 This is a schematic diagram illustrating the calculation process of machine tool spindle rotation error. Detailed Implementation

[0061] Example 1

[0062] This embodiment discloses a machine tool spindle rotation error detection device, such as... Figure 1As shown, the device includes a spindle housing a, a machine tool spindle b, and a machine tool control box c connected together. The spindle housing a is mounted on the upper end of the machine tool spindle b. The device also includes a sensor bracket 1 fixedly mounted on the outside of the spindle housing a. The sensor bracket 1 is arranged around the spindle housing a and extends to the machine tool spindle b. The length of the machine tool spindle b extending beyond the sensor bracket 1 is at least 40 mm, meaning that at least 40 mm of the machine tool spindle b under test should be exposed, of which a 15 mm section is a spindle or cylindrical tool holder with a smooth surface. The sensor bracket 1 has a stepped cylindrical structure with a T-shaped axial section, meaning that the diameter located outside the spindle housing a is larger than the diameter located outside the machine tool spindle b. Three threaded holes are provided on the sensor bracket 1 outside the machine tool spindle b, located on the same cross-section, namely the first cross-section: namely, first threaded hole A1-K1, first threaded hole B1-K2, and first threaded hole C1-K3; the angles of the first threaded holes A, B, and C in the circumferential direction of the cross-section are 0°, 83.6°, and 137.2°, respectively. Figure 2 As shown, eddy current sensors A2-1, B2-2, and C2-3 are respectively installed in the first threaded holes A, B, and C. The minimum clearance between the three eddy current sensors and the machine tool spindle surface is 1.5 mm to ensure that the measurement is within the linear range of the eddy current sensors. To achieve accurate measurement, high-precision eddy current sensors with an accuracy of 0.1 μm are used.

[0063] On the sensor bracket 1 located outside the machine tool spindle b, on the lower and upper sides of the first cross-section, there are two second threaded holes: namely, second threaded holes A1-K4 and second threaded holes B1-K5. The two second threaded holes are located on the same side of the same axial section as the first threaded hole A. Laser speed sensors A3-1 and B3-2 are respectively installed in the two second threaded holes. The laser speed sensors have an accuracy of sensing 20,000 pulses per second and outputting a 3V high-level pulse. The distance between the cross-section where the second threaded hole A is located (i.e., the second cross-section A) and the cross-section where the second threaded hole B is located (i.e., the second cross-section B) and the first cross-section is not less than 15mm.

[0064] A single reflector 4-1 is attached to the machine tool spindle b at the axial position corresponding to the second threaded hole A. The single reflector 4-1 is self-adhesive and adheres to the surface of the machine tool spindle. Its length is the same as the circumference of the machine tool spindle surface, and its entire length has a reflective strip. The height of the reflective strip is 8mm, and the width of the reflective strip is 1 / 20 of the circumference L of the machine tool spindle surface. Multiple reflectors 4-2 are attached to the machine tool spindle surface at the axial position corresponding to the second threaded hole B. The multiple reflectors 4-2 are self-adhesive and adhere to the surface of the machine tool spindle. Their length is the same as the circumference of the machine tool spindle surface, and 10 reflective strips of equal width are evenly distributed on the multiple reflectors 4-2. The width of the reflective strips is 1 / 20 of the circumference L of the machine tool spindle surface. When a single reflective strip 4-1 and multiple reflective strips 4-2 are attached to the surface of the machine tool spindle, the reflective strip on the single reflective strip 4-1 is aligned with any one of the reflective strips on the multiple reflective strips 4-2, such as... Figure 3 As shown.

[0065] Three third threaded holes are evenly provided on the sensor bracket 1 on the outside of the spindle housing a: namely, third threaded holes A1-K6, third threaded holes B1-K7, and third threaded holes C1-K8. Fastening bolts are installed in these three third threaded holes, and the sensor bracket 1 is fixedly connected to the spindle housing a by these bolts. The pitch of each threaded hole is 1 mm.

[0066] The device also includes a rotation error acquisition unit 5 and a rotation error detection host 6 connected inside the machine tool control box c. The rotation error acquisition unit 5 is used to acquire laser speed sensor signals and eddy current sensor signals and transmit the signal data to the rotation error detection host 6. The rotation error detection host 6 is used to control the rotation error acquisition unit 5, and to process the received signal data to obtain the machine tool spindle rotation error and store it.

[0067] The slewing error acquisition unit 5 is internally connected to a bandpass filter 5-HL, an AD converter 5-A, and a core processor 5-F in sequence; in this embodiment, the bandpass filter 5-HL is a filter with a frequency of 0.1Hz to 10000Hz. The core processor 5-F is also connected to counters 15-J1 and 25-J2; the bandpass filter 5-HL is connected to the three eddy current sensors to form three eddy current sensor signal acquisition channels 5-1, 5-2, and 5-3, with one channel as a spare channel 5-4; the core processor 5-F is connected to two laser speed sensors through two counters to form laser speed sensor signal acquisition channels, one of which is the speed acquisition channel 5-R, which acquires the laser pulse signals of laser speed sensors B corresponding to multiple reflectors, used for the rotation frequency and speed of the computer tool spindle; the other is the speed trigger acquisition channel 5-C, which acquires the laser pulse signals of laser speed sensors A corresponding to a single reflector 4-1, triggering the rotation error acquisition unit 5 to synchronously acquire the three eddy current sensor signals; the core processor 5-F is connected to the rotation error detection host 6 through an Ethernet communication interface. Among them, the bandpass filter 5-HL is used to filter the signal to ensure the signal validity; the AD converter 5-A is used to convert the analog signal into a digital signal; the core processor 5-F is used to encode the data of each channel into a data queue and transmit it to the rotation error detection host 6; the rotation error detection host 6 processes the received signal data to obtain the machine tool spindle rotation error and stores it.

[0068] After the detection device is started, the machine tool spindle begins to rotate. The rotation error acquisition unit 5 collects the laser pulse signals from the laser speed sensors B corresponding to multiple reflectors. By counting the number of pulses obtained within a set time, the rotation frequency and speed of the machine tool spindle can be calculated. The machine tool spindle is then adjusted to operate within a speed range of 30 r / min to 300 r / min. The sampling frequency is set according to the rotation frequency of the machine tool spindle. The laser pulse signal from the laser speed sensor A corresponding to a single reflector 4-1 triggers the spindle rotation error acquisition unit 5 to synchronously collect the displacement signals from three eddy current sensors at the sampling frequency. The displacement signals collected by the rotation error acquisition unit 5 are filtered by the bandpass filter 5-HL through the acquisition channel, converted by the AD converter 5-A, processed by the core processor 5-F, and then transmitted to the rotation error detection host 6 via the Ethernet communication interface for further processing to obtain and store the machine tool spindle rotation error.

[0069] Example 2

[0070] This embodiment discloses a method for detecting the rotational error of a machine tool spindle using the device described in Embodiment 1. The method includes the following steps:

[0071] Step 1: Start the machine tool spindle rotation error detection device. The machine tool spindle rotates, and the laser pulse signal M1 corresponding to the laser speed sensor B of multiple reflectors is collected. 10 The number of pulses obtained within a time period is N 10 Therefore, the rotation frequency f of the computer tool spindle r And the rotational speed n, and adjust the machine tool spindle to make it run within the range of 30r / min≤n≤300r / min.

[0072] The rotational frequency f of the machine tool spindle r The formula for calculating the rotational speed n is:

[0073] f r =(N 10 / t 10 ) / K (1)

[0074] n = 60 * f r (2)

[0075] In the formula, f r is the rotational frequency of the machine tool spindle, in Hz; K is the number of reflectors in the multi-reflector system; n is the rotational speed of the machine tool spindle, in r / min.

[0076] Step 2: Based on the rotational frequency f of the machine tool spindle r Set the sampling frequency f s The laser pulse signal M2 of the laser speed sensor A corresponding to a single reflector is collected. The spindle rotation error acquisition device is triggered by the M2 signal to sample at a frequency f. s Displacement signals from three eddy current sensors are acquired simultaneously; to ensure detailed sampling data, the sampling frequency is set to f. s =2048*f r .

[0077] Step 3: The slewing error acquisition unit performs preprocessing on the acquired displacement signal, including filtering, analog-to-digital conversion, and data queue assembly, and transmits the preprocessed signal data to the slewing error detection host. The slewing error detection host processes the received signal data to obtain the machine tool spindle slewing error.

[0078] The specific process by which the rotation error detection host processes the received signal data to obtain the machine tool spindle rotation error is as follows:

[0079] First, error separation is performed, and the synchronous sampling frequency f for each displacement signal is set. s =2048*f rThat is, 2048 data points are collected per week, and data is collected for 4 rotations of the spindle each time, that is, N=8192 data points. The 8192 data points collected each time are divided into 4 segments. Then, the average of the 4 segments is calculated point by point in sequence to form a new data sequence. Then, the spindle shape error and spindle rotation error are separated. The spindle shape error is the mechanical shape error during spindle machining, that is, the roundness error.

[0080] Separate the spindle shape error and establish a rectangular coordinate system with the center of the cross-section circle as the origin. Let eddy current sensor A2-1 be located on the X-axis of the rectangular coordinate system, and let the angles between eddy current sensors B2-2 and C2-3 and eddy current sensor A be β and α, respectively. Figure 4 As shown in the figure, ω is the direction of rotation of the principal axis. The displacement signals collected by the three eddy current sensors are V1, V2, and V3, respectively. Let r(θ) i ) represents the shape error of the machine tool spindle under test, x(θ) i ) and y(θ i Let θ represent the components of the spindle rotation error in the X and Y axes, respectively. Then, the acquired displacement signal corresponds to the angle θ through which the machine tool spindle rotates relative to eddy current sensor A. i The relationships between them are shown in equations (3) to (5):

[0081] V1(θ i ) = r(θ i )+ x(θ i (3)

[0082] V2(θ i ) = r(θ i +β)+ x(θ i cosβ+ y(θ) i sinβ (4)

[0083] V3(θ i ) = r(θ i + α)+ x(θ i cos α + y(θ) i sin α (5)

[0084] In the formula, r(θ) i ), x(θ) i ), y(θ) i The calculation process is as follows: First, determine the relationship between θi and the number of sampling points N:

[0085] θ i = 2πi / (N / 4) (6)

[0086] In the formula, i = 1, 2, ..., N / 4, where N is 8192. Weighting coefficients m1, m2, and m3 are then introduced into the displacement signals collected by the three eddy current sensors for weighting processing. The weighted V(θ) is then calculated. i )for:

[0087] V(θi)=m1V1(θ i )+m2V2(θ i )+m3V3(θ i )

[0088] =m1r(θ) i )+m2r(θ i +β)+m3r(θ i +α)+(m1+m2 cosβ+

[0089] m3 cosα)x(θ i )+(m2 sinβ+m3 sinα)y(θ i (7)

[0090] To calculate the components of the spindle rotation error in the X and Y axes, it is necessary to separate the shape error present in the weighted signal. Let the coefficients of the X and Y axis components of the rotation error be set to 0, that is:

[0091] m1+ m2 cos β+ m3 cos α = 0 (8)

[0092] m2 sin β+ m3 sin α = 0 (9)

[0093] Let the weighting coefficient m1 = 1 for eddy current sensor A, then the weighting coefficients m2 and m3 for eddy current sensors B and C can be expressed as follows:

[0094] m2 = -sinα / sin(α-β) (10)

[0095] m3 = sinβ / sin(α-β) (11)

[0096] The signal that retains only the spindle shape (roundness) error can be expressed as:

[0097] V(θ i ) = r(θ i ) + m2 r(θ i +β) + m3 r(θ i +α) (12)

[0098] For r(θ) in the above formula i The Fourier transform of the given information is as follows:

[0099] V'(j) = r'(j)·H(j) (13)

[0100] In the formula, V'(j) and r'(j) are respectively V(θ) i ) and r(θ i The Fourier transform result of ), where j is the harmonic order; H(j) is the weight function in the Fourier transform:

[0101] H(j) = 1 + m2e jkβ +m3e jkα

[0102] = 1 -sinα / sin(α-β)e jkβ + sinβ / sin(α-β)e jkα (14)

[0103] Performing an inverse Fourier transform on r'(j) yields r(θ) i ):

[0104] r(θ i =IFFT(r'(j)) (15)

[0105] In the formula, IFFT() means performing an inverse Fourier transform on the data sequence within the parentheses.

[0106] Therefore, the rotational error of the spindle can be obtained, and its components x(θ) in the X and Y axes. i ) and y(θ i They are respectively:

[0107] x(θ i ) = s1(θ i )-r(θ i (16)

[0108] y(θ i ) = [s2(θ i )-r(θ i +α)-x(θ i )cosα] / sinα (17)

[0109] Then, the data sequence is plotted as a ring shape. Inscribed circle O1 and circumscribed circle O2 are drawn inside and outside the ring shape, respectively. The diameters and radii of the inscribed circle O1 and circumscribed circle O2 are D1 and D2, and R1 and R2, respectively. Figure 5 As shown.

[0110] Then, the circumscribed circle radius R2 is calculated as the spindle shape (roundness) error, and the difference between the circumscribed circle and the inscribed circle radius R2-R1 is calculated as the spindle rotation error. In this embodiment, the calculated spindle shape error is: R2 = 2.1μm, and the spindle rotation error is: R2-R1 = 2.1μm-1.9μm = 0.2μm.

[0111] Finally, it should be noted that the above description is only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred arrangement, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A machine tool spindle rotation error detection device, comprising a spindle housing (a), a machine tool spindle (b), and a machine tool control box (c) connected together, wherein the spindle housing (a) is mounted on the upper end of the machine tool spindle (b), characterized in that, The device further includes a sensor bracket (1) fixedly installed on the outside of the spindle headbox (a). The sensor bracket (1) is arranged around the spindle headbox (a) and extends to the machine tool spindle (b). Three first threaded holes (1-K1, 1-K2, 1-K3) located in the first cross-section are provided on the sensor bracket (1) outside the machine tool spindle (b). The angles of the three first threaded holes (1-K1, 1-K2, 1-K3) in the circumferential direction of the first cross-section are 0°, 83.6°, and 137.2°, respectively. Eddy current sensors (2-1, 2-2, 2-3) are respectively installed in the first threaded holes; on the sensor bracket (1) outside the machine tool spindle (b), a second threaded hole (1-K4, 1-K5) is also provided on both sides below the first cross section. The two second threaded holes and one of the first threaded holes are located on the same side of the same axial section. Laser speed sensors (3-1, 3-2) are respectively installed in the two second threaded holes; on the machine tool spindle (b), the axial positions corresponding to the two second threaded holes are... A single reflector (4-1) and a multi-reflector (4-2) are respectively attached to the machine tool spindle (b). The length of both the single reflector (4-1) and the multi-reflector (4-2) is the same as the circumference of the machine tool spindle (b). Ten reflective strips of equal width are evenly distributed on the multi-reflector (4-2). The single reflector (4-1) has one reflective strip with the same width as the reflective strips on the multi-reflector (4-2). The reflective strip on the single reflector (4-1) and the multi-reflector... One of the reflective strips on the plate (4-2) is aligned; the device also includes a rotation error acquisition unit (5) and a rotation error detection host (6) connected inside the machine tool control box (c). The rotation error acquisition unit (5) is used to acquire the laser speed sensor signal and the eddy current sensor signal and transmit the signal data to the rotation error detection host (6). The rotation error detection host (6) is used to control the rotation error acquisition unit (5) and to process the received signal data to obtain the machine tool spindle rotation error and store it.

2. The machine tool spindle rotation error detection device according to claim 1, characterized in that, The slewing error acquisition unit (5) is internally connected to a bandpass filter (5-HL), an AD converter (5-A), and a core processor (5-F). The core processor (5-F) is also connected to two counters (5-J1, 5-J2). The core processor (5-F) is connected to two laser speed sensors through the two counters to form a laser speed sensor signal acquisition channel. The bandpass filter (5-HL) is connected to three eddy current sensors to form an eddy current sensor signal acquisition channel. The core processor (5-F) is connected to the slewing error detection host (6) through an Ethernet communication interface.

3. The machine tool spindle rotation error detection device according to claim 1, characterized in that, The minimum gap between the three eddy current sensors (2-1, 2-2, 2-3) and the surface of the machine tool spindle is 1.5 mm.

4. The machine tool spindle rotation error detection device according to claim 1, characterized in that, The distance between the cross-sections containing the two second threaded holes and the first cross-section is not less than 15 mm.

5. The machine tool spindle rotation error detection device according to claim 1, characterized in that, Three third threaded holes are evenly provided on the sensor bracket (1) on the outside of the main spindle housing (a), and the sensor bracket (1) is fixedly connected to the main spindle housing (a) by fastening bolts.

6. The machine tool spindle rotation error detection device according to claim 1, characterized in that, The eddy current sensor has an accuracy of 0.1 μm, and the laser rotation speed sensor has an accuracy of sensing 20,000 pulses per second and outputting a 3V high-level pulse.

7. A method for detecting the rotational error of a machine tool spindle based on the device described in any one of claims 1 to 6, characterized in that, The method includes the following steps: Step 1: Start the machine tool spindle rotation error detection device. The machine tool spindle rotates, and the laser pulse signal M1 from the laser speed sensor corresponding to multiple reflectors is collected. (The last part, "t," appears to be incomplete and possibly refers to a specific step or step. It doesn't translate directly but can be left as is.) 10 The number of pulses obtained within a time period is N 10 Therefore, the rotation frequency f of the computer tool spindle r And the rotational speed n, and adjust the machine tool spindle to make it run within the range of 30r / min≤n≤300r / min; The rotational frequency f of the machine tool spindle r The formula for calculating the rotational speed n is: f r =(N 10 / t 10 ) / K (1) n=60*f r (2) In the formula, f r is the rotational frequency of the machine tool spindle, in Hz; K is the number of reflectors in the multi-reflector system; n is the rotational speed of the machine tool spindle, in r / min; Step 2: Based on the rotational frequency f of the machine tool spindle r Set the sampling frequency f s The laser pulse signal M2 of the laser speed sensor corresponding to a single reflector is collected, and the spindle rotation error acquisition device is triggered by the M2 signal to sample at a frequency f. s Displacement signals from three eddy current sensors are acquired simultaneously; the sampling frequency is set to f. s =2048*f r ; Step 3: The slewing error acquisition unit performs preprocessing on the acquired displacement signal by filtering, analog-to-digital conversion, and data queue assembly, and transmits the preprocessed signal data to the slewing error detection host. The slewing error detection host processes the received signal data to obtain the machine tool spindle slewing error.

8. The method for detecting the rotational error of a machine tool spindle according to claim 7, characterized in that, The specific process by which the rotation error detection host processes the received signal data to obtain the machine tool spindle rotation error is as follows: First, error separation is performed, and the synchronous sampling frequency f for each displacement signal is set. s =2048*f r That is, 2048 data points are collected per week, and the data points are collected for 4 rotations of the spindle each time, that is, N=8192 data points. The 8192 data points collected each time are divided into 4 segments, and the average of the 4 segments is calculated point by point in sequence to form a new data sequence. Then, the spindle shape error and spindle rotation error are separated. The spindle shape error is separated, and a rectangular coordinate system is established with the center of the cross-section circle as the origin. One eddy current sensor is located on the X-axis of the rectangular coordinate system, and the angles between the other two eddy current sensors and the X-axis are β and α, respectively. The displacement signals acquired by the three eddy current sensors are V1, V2, and V3, respectively. Let r(θ) i ) represents the shape error of the machine tool spindle under test, x(θ) i ) and y(θ i Let θ represent the components of the spindle rotation error in the X and Y axes, respectively. Then, the acquired displacement signal corresponds to the angle θ through which the machine tool spindle rotates relative to the eddy current sensor located on the X-axis. i The relationship between them is: V1(θ i ) = r(θ i )+ x(θ i ) (3) V2(θ i ) = r(θ i +β)+ x(θ i )cosβ+ y(θ i )sinβ (4) V3(θ i ) = r(θ i + a)+ x(θ i )cos α + y(θ i )sin α (5) In the formula, r(θ) i ), x(θ) i ), y(θ) i The calculation process is as follows: First, determine the relationship between θi and the number of sampling points N: i i = 2πi / (N / 4) (6) In the formula, i = 1, 2, ..., N / 4, where N is 8192. Weighting coefficients m1, m2, and m3 are then introduced into the displacement signals collected by the three eddy current sensors for weighting processing. The weighted V(θ) is then calculated. i )for: V(θi) = m1V1(θ i ) + m2V2(θ i ) + m3V3(θ i ) = m1r(θ i )+ m2r(θ i + b)+ m3r(θ i + a)+ (m1+ m2 cosβ+ m3 cos α)x(θ i ) + (m2 sin β+ m3 sin α)y(θ i ) (7) Calculate the components of the spindle rotation error in the X and Y axes, then separate the shape error present in the weighted signal; set the coefficients of the rotation error components in the X and Y axes to 0, that is: m1+ m2 cos β+ m3cos α = 0 (8) m2 sin β+ m3 sin α = 0 (9) Let the weighting coefficient m1 = 1 for the eddy current sensor located on the X-axis, then the weighting coefficients m2 and m3 are expressed as follows: m2 = -sinα / sin(α-β) (10) m3 = sinβ / sin(α-β) (11) The signal that retains only the spindle shape error is represented as follows: V(θ i ) = r(θ i ) + m2 r(θ i +β) + m3 r(θ i +α) (12) For r(θ) in the above formula i The Fourier transform of the given information is as follows: V'(j) = r'(j)·H(j) (13) In the formula, V'(j) and r'(j) are respectively V(θ) i ) and r(θ i The Fourier transform result of ), where j is the harmonic order; H(j) is the weight function in the Fourier transform: H(j) = 1 + m2e jkβ +m3e jkα = 1 -sinα / sin(α-β)e jkβ + sinβ / sin(α-β)e jkα (14) Performing an inverse Fourier transform on r'(j) yields r(θ) i ): r(θ i )=IFFT(r’(j)) (15) In the formula, IFFT() represents performing an inverse Fourier transform on the data sequence within the parentheses; From this, the rotational error of the spindle can be obtained, its components x(θ) in the X and Y axes. i ) and y(θ i They are respectively: x(θ i ) = V1 (θ i )-r(θ i ) (16) y(θ i ) =[V3 (θ i )-r(θ i +α)-x(θ i )cosα] / sina (17) Then, the data sequence is plotted into a ring shape. In the ring shape, an inscribed circle O1 and an circumscribed circle O2 are drawn inside and outside the ring shape, respectively. The diameters and radii of the inscribed circle O1 and the circumscribed circle O2 are D1 and D2, and R1 and R2, respectively. The radius of the circumscribed circle R2 is calculated as the spindle shape error, and the difference between the radii of the circumscribed circle and the inscribed circle R2-R1 is calculated as the spindle rotation error.

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