A detection method of a ball spline shaft raceway straightness detection instrument

Abstract

The application relates to a detection method of a ball spline shaft raceway straightness detection instrument. First, a space relative coordinate system of a to-be-detected ball spline shaft is constructed through parameters of the to-be-detected spline shaft; a plane parallel to the head-tail frame center in the Y-axis direction is set as an X-Z plane, and an arbitrary point of the maximum outer circle of the ball spline shaft in the horizontal direction is taken as a coordinate system origin (0, 0); the spline shaft outer circle parameters are measured through a probe; the measured spline shaft is rotated, the probe is aligned with the raceway, and (x g0 , 0) is obtained; when the probe moves in the X-axis direction, n data points (x gi , z gi ) are obtained, and the real raceway (x i , z i ) is calculated; the data points (x i , z i ) are fitted through a least square method, a ball spline shaft raceway fitting straight line x=bz+a and specific deviation can be obtained. The application can detect the straightness deviation of the ball spline shaft raceway.

Description

Technical Field

[0001] This invention relates to a testing method for the straightness of the raceway of a ball spline shaft. It belongs to the field of straightness testing technology. Background Technology

[0002] As a crucial component of ball spline pairs, the ball spline shaft significantly impacts the overall performance of the spline pair. The straightness of the ball raceways directly affects the friction, wear, accuracy retention, lifespan, rigidity, and vibration noise of the spline pair. Therefore, to improve the performance of domestically produced ball spline pairs, it is essential to test the straightness parameter of the ball raceways.

[0003] Currently, the straightness of pipes is measured by placing the pipe on a flat platform, rolling it, and using a feeler gauge to measure the gap between the bent section and the surface of the marble platform. This method relies on manual inspection, is prone to human error, has low efficiency, and is unsuitable for batch inspection. In July 2022, a new measurement method was proposed in a published patent (CN115112031A) for measuring the outer diameter and straightness of pipes. This method involves loading the pipe onto several rotating components, aligning one end of the pipe with a positioning plate, and then sliding the measuring component along the length of a slide rail to measure the straightness. However, this method involves multiple rotating components, which increases the potential for installation errors.

[0004] The calculation methods for tube and shaft components are not applicable to the straightness calculation of ball spline shaft raceways, and there are no specific calculation methods for ball spline shaft raceways. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a detection method for a ball spline shaft raceway straightness testing instrument, which is based on the above-mentioned prior art, and realizes the calculation of the straightness of the ball spline shaft raceway.

[0006] The technical solution adopted by this invention to solve the above problems is as follows: a detection method for a ball spline shaft raceway straightness testing instrument, wherein the matching method is used to measure n data points of the ball raceway of the ball spline shaft and calculate the straightness of the ball raceway of the ball spline shaft, and the method includes the following steps:

[0007] Step 1: Construct a spatial relative coordinate system for the roller spline shaft, where the X-axis is the horizontal radial direction of the spline shaft, the Y-axis is the vertical diameter direction of the spline shaft, and the Z-axis is the length direction of the spline shaft.

[0008] Step 2: Determine the tool setting point at the maximum outer diameter of the splined shaft, and measure n data points (x, y, y) along the Z-axis. ri ,z ri), measure three times and take the average, i∈[1,n];

[0009] Step 3: Place the probe at the tool setting point and make contact with the raceway, and measure n data points (x, y, z) along the Z-axis of the spline shaft raceway. gi ,z gi ), and calculate the actual raceway data (x 滚 ,z 滚 i∈[1,n];

[0010] Step 4: Fit the data points after eliminating the bias using the least squares method and calculate the equation of the fitted line of the raceway.

[0011] Step 5: Repeat steps 3 and 4 to calculate the fitted linear equations for the ball raceways of all ball spline shafts.

[0012] Preferably, the specific measurement process in step 2 is as follows:

[0013] Using a ball-end probe to contact the maximum outer diameter of the spline shaft in the X direction, determine the tool setting point A(0,0), and move along the Z-axis to collect n position data points A'1(x). 1ri ,z 1ri Rotate the spline shaft 120° and repeat the above operation to obtain A'2(x). 2ri ,z 2ri ), A'3(x 3ri ,z 3ri ), i∈[0,n]; take the average of three measurements, (x ri ,z ri ),

[0014]

[0015] z ri =z 1ri =z 2ri =z 3ri , i∈[0,n].

[0016] Preferably, the specific process of measuring the spline shaft raceway data points in step 3 is as follows:

[0017] Using a ball-head probe, the probe returns to the tool setting point (0,0) and moves along the X-axis until it contacts the raceway, resulting in B(x). g0 ,0); the probe moves along the Z-axis, and then n data points B'(x) are obtained. gi ,z gi ), i∈[0,n]; the measurement error in the X direction caused by the installation deviation of the spline shaft X-axis and Y-axis is x. rix x riy Therefore, x ri It consists of three parts, namely x ri =xrix +x riy +x 轴 Similarly, the data points of the raceway

[0018] x gi =x rix +x riy +x 轴 +x 滚 (2)

[0019] Obtain real track data

[0020] x 滚 =x gi -x ri (3)

[0021] z 滚 =z gi =z ri .

[0022] Preferably, in step 4, the least squares method is used to calculate the fitted straight line of the ball raceway of the ball spline shaft, as follows:

[0023] 4.1 Let x i =x 滚 , z i =z 滚 =z, the expression for the line is set as

[0024] x = bz + a (4)

[0025] The best estimates of parameters a and b are

[0026]

[0027]

[0028] 4.2 Substitute a and b into the straight line formula x = bz + a to obtain the mathematical model of the raceway straight line, and calculate the straightness deviation |x 终点 -x 起点 |

[0029] Compared with the prior art, the advantages of the present invention are as follows:

[0030] 1) The detection method of the present invention is specifically used for calculating the straightness of the raceway of a ball spline shaft relative to the axis;

[0031] 2) Traditional head and tailstock installation errors cause the spline shaft axis to be non-parallel to the bottom guide rail of the sensor, which will cause the measured data in the X direction to contain installation errors. The calculation method of the present invention eliminates this installation error. Attached Figure Description

[0032] Figure 1This is a flowchart of the matching method for the ball spline shaft raceway straightness testing instrument of the present invention.

[0033] Figure 2 This is a schematic diagram of the overall structure of the ball spline shaft ball raceway straightness measuring device of the present invention.

[0034] Figure 3 for Figure 2 Top view.

[0035] Figure 4 This is a schematic diagram of the structure of the mobile platform in an embodiment of the present invention.

[0036] Figure 5 for Figure 4 Top view.

[0037] Figure 6 This is a schematic diagram of the Z-axis moving platform in an embodiment of the present invention.

[0038] Figure 7 for Figure 6 The front view.

[0039] Figure 8 for Figure 7 A magnified view of the contact between the central columnar contact and the transmission lead screw.

[0040] Figure 9 This is a geometric diagram showing the start and end detection points of the probe in an embodiment of the present invention. Detailed Implementation

[0041] The following description, in conjunction with the accompanying drawings and specific embodiments, further explains and illustrates the high-strength, high-toughness, low-carbon gear steel and its performance testing according to the present invention. However, this explanation and description do not constitute an undue limitation on the technical solution of the present invention.

[0042] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0043] like Figure 1 As shown, this embodiment provides a matching method for a ball spline shaft raceway straightness testing instrument, including calculating n data points of the ball raceway of the ball spline shaft.

[0044] Given the following: Z-axis data of the leadscrew, maximum outer diameter measurement data of the leadscrew, and X-axis measurement data of the outer diameter of a single raceway of the leadscrew shaft:

[0045] Table 1. Lead screw axis data in the z-direction (mm)

[0046]

[0047]

[0048] Table 2. Three measurements of the maximum outer diameter of the lead screw in the x-direction (mm)

[0049]

[0050] Table 3. Measurement data of the outer diameter of a single raceway of the lead screw shaft in the x-direction / mm

[0051]

[0052] According to the formula The mean value of the outer diameter of the ball screw, x, can be calculated. ri / mm

[0053] Table 4 shows the average of three measurements of the outer diameter of the ball screw in mm.

[0054]

[0055] The data value of the first raceway can be obtained using the formula.

[0056] x 滚 =x gi -x ri

[0057] Table 5 shows the actual data values ​​for calculating the raceway x roller.

[0058]

[0059] Let x i =x 滚 ,z i =z 滚 =z, according to formula (4), the linear expression is set as

[0060] x = bz + a, let x i , z i Substitute into formulas (5) and (6)

[0061]

[0062]

[0063] We get a = -3.551, b = 0.005, and the equation of the line becomes x = 0.005z - 3.551;

[0064] Take the x-values ​​of the two endpoints as the straightness tolerance: x 起点 =0.005*10-3.551=-3.501mm,x 终点=0.005*10-3.551=-3.051mm

[0065] Raceway straightness deviation |x 终点 -x 起点 |=0.45mm.

[0066] like Figure 2-3 As shown, based on the above detection method, this embodiment provides a ball spline shaft raceway straightness testing instrument, including a bed worktable, a probe 1, an upper moving platform 2, a ball spline shaft to be tested 3, a tailstock 4, a Z-axis horizontal moving platform 5, and a headstock 6; the tailstock 4, the Z-axis horizontal moving platform 5, and the headstock 6 are all mounted on the bed worktable; a drive motor is fixed on the bed worktable, and the drive motor is connected to the Z-axis horizontal moving platform 5 through a lead screw mechanism; a linear slide rail pair is provided between the Z-axis horizontal moving platform 5 and the bed worktable; the drive motor is connected to the Z-axis horizontal moving platform 5 through a lead screw mechanism for driving the Z-axis horizontal moving platform. The horizontal moving platform 5 moves horizontally and linearly on the bed worktable; the tailstock 4 and headstock 6 are respectively set on both sides of the Z-axis horizontal moving platform 5, and the tailstock 4 and headstock 6 are used to support the ball spline shaft 3 to be tested; the Z-axis horizontal moving platform 5 is provided with a parallel upper moving platform 2; the Z-axis horizontal moving platform 5 is provided with a linear slide rail pair along the X-axis direction, and the upper moving platform 2 is driven to move linearly along the linear slide rail pair by a knob; the probe 1 is located on the upper moving platform 2, and the probe 1 is used to collect the straightness value of the ball spline shaft 3 to be tested; the bed worktable is provided with a grating ruler, which is used to provide the Z-axis position of the probe collection point.

[0067] like Figure 4-5 As shown, the upper moving platform 2 includes a grating-sensor mount 2-1, a guide rail 2-2, a nut seat 2-3, a rotary dial 2-4, a slider 2-5, a spring 2-6, and a gear shaft 2-7. The probe 1 is mounted on the grating-sensor mount 2-1, allowing for X-axis displacement and data acquisition. The grating-sensor mount 2-1 is bolted to the slider 2-5. The upper moving platform 2 has threaded holes for fixing the guide rail 2-2 and the nut seat 2-3. The slider 2-5 engages with the guide rail 2-2 via a guide rail groove and with the rotary dial 2-4 via the spring 2-6 and the gear shaft 2-7. The rotary dial 2-4 is mounted on the nut seat 2-3. Rotating the rotary dial 2-4 moves the grating-sensor mount along the X-axis via the gear shaft 2-7. The spring 2-6 connects the slider 2-5 and the nut seat 2-3 to prevent the slider from loosening during operation.

[0068] like Figure 6-8As shown, the Z-axis moving platform 5 includes a transmission screw 5-1, a columnar contact rod 5-2, a grating ruler 5-3, a connecting plate 5-4, and a displacement sensor 5-5. The grating ruler 5-3 is mounted perpendicular to the Z-axis on the machine bed, and the displacement sensor 5-5 is mounted on the Z-axis moving platform 5 via the connecting plate 5-4. The columnar contact rod 5-2 is parallel to the Y-axis, mounted on the side of the Z-axis moving platform 5, and contacts the transmission screw 5-1. The transmission screw 5-1 rotates to drive the Z-axis moving platform 5 to move in the Z-axis direction, and the displacement data is measured by the displacement sensor 5-5.

[0069] The probe 1 includes two types of probes: ball-head probes and panel-head probes. They are installed in the same location and used in the same way. The panel-head probe has a built-in sensor on its panel, which can detect data points.

[0070] like Figure 9 As shown, during the measurement using the above-mentioned testing instrument, a ball-tipped probe is used to contact the outermost point of the X-axis to determine the tool setting point A(0,0), and then moves along the Z-axis to collect n position data points A'1(x). 1ri ,z 1ri Rotate the spline shaft 120° and repeat the measurement operation to obtain A'2(x). 2ri ,z 2ri ), A'3(x 3ri ,z 3ri ), i∈[1,n]; take the average of three measurements, (x ri ,z ri Still using the ball-end probe, the probe returns to the tool setting point (0,0) and moves along the X-axis until it contacts the raceway, resulting in B(x). g0 ,0); The probe moves along the Z-axis, and n data points B,(x gi ,z gi ), i∈[1,n]; because the installation error of the head and tailstock causes the spline shaft axis to be non-parallel to the bottom guide rail of the sensor, that is, the X-direction measurement error x caused by the installation deviation of the head and tailstock X-axis and Y-axis. rix x tiy Therefore, x ri It consists of three parts, namely x ri =x rix +x tiy +x 轴 Similarly, the data point x on the raceway gi =x rix +x riy +x 轴 +x 滚 Obtain the actual raceway data x i =x 滚 =x gi -x ri , z i =z滚 =z gi =z ri . The data points (x i ,z i By performing least squares fitting, the fitting line x = bz + a of the ball spline shaft raceway and the specific deviation can be obtained.

[0071] In addition to the above embodiments, the present invention also includes other embodiments. All technical solutions formed by equivalent transformation or equivalent substitution should fall within the protection scope of the claims of the present invention.

Claims

1. A method for testing the straightness of a ball spline shaft raceway, the method being used to measure n data points of the ball raceway of the ball spline shaft and calculate the straightness of the ball raceway of the ball spline shaft, characterized in that... The method includes the following steps: Step 1: Construct a spatial relative coordinate system for the roller spline shaft, where the X-axis is the horizontal radial direction of the spline shaft, the Y-axis is the vertical diameter direction of the spline shaft, and the Z-axis is the axial direction of the spline shaft; Step 2: Determine the tool setting point at the maximum outer diameter of the splined shaft, and measure n data points (x, y, y) along the Z-axis. ri ,z ri ), measure three times and take the average, i∈[1,n]; Step 3: Place the probe at the tool setting point and make contact with the raceway, and measure n data points (x, y, z) along the Z-axis of the spline shaft raceway. gi ,z gi ), and calculate the actual raceway data (x 滚 ,z 滚 i∈[1,n]; Step 4: Fit the data points after eliminating the bias using the least squares method and calculate the equation of the fitted line of the raceway. Step 5: Repeat steps 3 and 4 to calculate the fitted linear equations for the ball raceways of all ball spline shafts.

2. The method for detecting the straightness of the raceway of a ball spline shaft according to claim 1, characterized in that: The specific measurement process in step 2 is as follows: Using a ball-end probe to contact the maximum outer diameter of the spline shaft in the X direction, determine the tool setting point A(0,0), and move along the Z-axis to collect n position data points A. ,1 (x 1ri ,z 1ri Rotate the splined shaft 120° and repeat the above operation to obtain A. ,2 (x 2ri ,z 2ri ), A ′3 (x 3ri ,z 3ri ), i∈[0,n]; take the average of three measurements, (x ri ,z ri ), With ri =z 1ri =z 2ri =z 3ri ,i∈[0,n]。 3. The testing method for the ball spline shaft raceway straightness testing instrument according to claim 1, characterized in that: The specific process for measuring the splined shaft raceway data points in step 3 is as follows: Using a ball-head probe, the probe returns to the tool setting point (0,0) and moves along the X-axis until it contacts the raceway, resulting in B(x). g0 ,0); the probe moves along the Z-axis, and then n data points B′(x,0) are obtained. gi ,z gi ), i∈[0,n]; the measurement error in the X direction caused by the installation deviation of the spline shaft X-axis and Y-axis is x. rix x riy Therefore, x ri It consists of three parts, namely x ri =x rix +x riy +x 轴 Similarly, the data points of the raceway x gi =x rix +x riy +x 轴 +x 滚 (2) Obtain real track data x 滚 =x gi ―x ri (3) With 滚 =z gi =z ri 。 4. The detection method of the ball spline shaft raceway straightness testing instrument according to claim 1, characterized in that: in step 4, the least squares method is used to calculate the fitted straight line of the ball spline shaft ball raceway, as follows: 4.1 Let x i =x 滚 , z i =z 滚 =z, the expression for the straight line is set as x = bz + a (4) The best estimates of parameters a and b are 4.2 Substitute a and b into the straight line formula x = bz + a to obtain the mathematical model of the raceway straight line, and calculate the straightness deviation |x 终点 ―x 起点 |

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