A leveling method for a three-point supported turntable based on autocollimator measurement

Abstract

Precision rotary tables are crucial instruments for measuring the shape and manufacturing precision of rotary parts. However, the inclination of the working surface relative to the axis of rotation introduces significant measurement errors into the workpiece contour or working angle measurements. Therefore, it is necessary to level the rotary platform so that the platform's surface normal is parallel to the axis of rotation. Leveling the turntable eliminates angle measurement errors caused by platform inclination when using an autocollimator in conjunction with the turntable. This leveling method boasts advantages such as simple mathematical principles, high leveling accuracy, and high operability, providing a feasible approach for automatic turntable leveling. The proposed method achieves leveling of a three-point supported turntable through autocollimator measurement. Before leveling, the inclination state of the rotary platform is calculated using the autocollimator. Based on the inclination state, the adjustment amount of the support feet is further calculated. Finally, the leveling operation is completed based on the adjustment amount and the autocollimator measurement.

Description

Technical Field

[0001] This invention relates to a leveling method for a three-point supported turntable based on autocollimator measurement. Background Technology

[0002] Precision rotary tables are crucial instruments for measuring the shape and manufacturing accuracy of rotary parts. However, the inclination of the working surface relative to the axis of rotation introduces significant measurement errors into the workpiece contour or working angle measurements. Therefore, it is necessary to level the rotary platform so that the platform's surface normal is parallel to the axis of rotation. Leveling the rotary table eliminates angle measurement errors caused by platform inclination when using an autocollimator in conjunction with the rotary table. This leveling method offers advantages such as simple mathematical principles, high leveling accuracy, and high operability, providing a feasible approach for automatic rotary table leveling. Summary of the Invention

[0003] This invention provides a leveling method for a three-point supported turntable based on autocollimator measurement. The basic idea of ​​this method is to first obtain the tilt state of the turntable by autocollimator measurement and then adjust the height of the support points to achieve leveling.

[0004] This leveling method has the advantages of simple mathematical principles and high leveling accuracy, and can provide a feasible approach for automatic leveling of turntables.

[0005] The prerequisites for using this invention are:

[0006] a. The turntable's support platform has three support points, such as a support platform using 3V kinematic connections;

[0007] b. In order to measure the tilt state of the platform, an autocollimator needs to be set up in the direction perpendicular to the axis of rotation of the turntable, and the autocollimator can measure the angle in two directions;

[0008] c. An optical prism with three or more working faces is required, i.e., the prism face number requirement is met. n ≥3.

[0009] To achieve leveling of the three-point support turntable, the specific operating steps are as follows:

[0010] Step 1: Place an optical prism in the center region of a turntable supported by three points. The optical prism has a total of n One side, n ≥ 3; Adjust the relative angle between the prism and the turntable so that the normal to any working face of the prism is parallel to the line connecting any turntable support point and the center of the turntable. Denote this working face of the prism and the turntable support point as face A. P 1. Support point, determine this position as the measurement zero point;

[0011] Step 2: Rotate the turntable so that surface A is aligned with the autocollimator, that is, align the autocollimator with the measurement obtained from surface A. X The axis angle value is within the arcsecond range, at which point the autocollimator is measured. Y Axis angle i 1;

[0012] Step 3: Rotate the turntable clockwise, and as described in Step 2, measure the B, C...X faces of the optical prism respectively. Y Axis angle i n The X side is the first n noodle;

[0013] Step 4: Rotate the turntable to align face A with the autocollimator again. Then, keeping the turntable stationary, rotate the prism to align face B with the autocollimator. At this point, measure the autocollimator. Y Axis angle i n+1 ;

[0014] Step 5: Rotate the turntable so that plane C is aligned with the autocollimator. At this time, measure the autocollimator. Y Axis angle i n+2 ;

[0015] Step Six: Solve the system of equations to find the platform tilt angle. i p and tilt direction i 0,

[0016] ,

[0017] Among them, the platform tilt angle i p This refers to the angle between the platform normal and the axis of rotation, and the direction of tilt. i 0 refers to the angle between the projection of the line connecting the highest and lowest points of the platform and the inner normal of surface A at the zero measurement point onto the plane perpendicular to the rotation axis. f a This refers to the perpendicularity error of face A of the prism relative to the base of the prism, and so on. β ab This represents the angle between the normals of surface A and surface B, which is the central angle corresponding to the two working surfaces, and so on.

[0018] Step 7: Based on the tilt direction in Step 6 i The value of 0 is used to represent the support columns of a three-point support platform in the following three cases. P 1. P 2. P 3. Make adjustments to achieve platform leveling and support columns. P 1. P 2. P3. Arranged in a clockwise direction:

[0019] a. If i 0 is between 0° and 60° or between 180° and 240°, adjust surface A so that its normal line is aligned with the support point. P 1. The line connecting the center of the turntable and the center of the circle are parallel. Rotate the turntable so that surface A is aligned with the autocollimator, and adjust the support column. P The height of 1 makes the autocollimator Y Increase in shaft angle measurement value i p cos i 0- 0.57735 i p sin i 0; Adjust surface A so that its normal line is aligned with the support point. P 3. The line connecting the center of the turntable and the center of the circle are parallel. Rotate the turntable so that surface A is aligned with the autocollimator, and adjust the support column. P The height of 3 makes the autocollimator Y The measured shaft angle increased by -1.15470°. i p sin i 0;

[0020] b. If i 0 is between 60° and 120° or 240° and 300°. Adjust surface A as described in a and perform measurements with the autocollimator. First, adjust the support column. P The height of 2 makes the autocollimator Y The shaft angle measurement value increased - i p cos i 0+ 0.57735 i p sin i 0, then adjust the support column. P The height of 3 makes the autocollimator Y The measured shaft angle increased by -0.57735 degrees. i p sin i 0- i p cos i 0;

[0021] c. If i 0 is between 120° and 180° or between 300° and 360°. Adjust surface A as described in a and perform measurements with the autocollimator. First, adjust the support column. P The height of 1 makes the autocollimator Y Increase in shaft angle measurement value i p cos i 0+ 0.57735 i p sin i 0, then adjust the support column. P The height of 2 makes the autocollimator Y The measured shaft angle increased by 1.15470°. i p sin i 0. Attached Figure Description

[0022] Figure 1 The structure of the support platform and its spindle to which this invention is applied.

[0023] Figure 2 The support platform structure for the 3V kinematic connection of the present invention is applicable.

[0024] Figure 3 , Figure 4 This invention describes the vector representation of platform tilt on which the present invention is based.

[0025] Figure 5 The mathematical principle of balancing.

[0026] Figure 6 This is a schematic diagram of the operation corresponding to the leveling steps two and four of the implementation plan.

[0027] Figure 7 This is a schematic diagram illustrating the operation of adjusting the support feet. Detailed Implementation Plan

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the number of faces of the prism is given below in conjunction with the accompanying drawings. n Analysis example when =4.

[0029] The basic configuration of a three-point support turntable is as follows: Figure 1 As shown, it includes a main shaft 1, support columns 2, and support platform 4. The bearing components are not shown in the drawing. The three support columns 2 support the platform 4. The angle between the platform surface normal 3 and the turntable axis 5 is denoted as the platform tilt angle. i p ;

[0030] The support platform 4 is connected to the spindle 1 via a 3V kinematic connection, and its structure is as follows: Figure 2 As shown, the lower surface of the support platform 4 has three V-grooves 6 spaced 120° apart; when the support column 2 on the main shaft 1 contacts and fully engages with the V-grooves 6, there are a total of six contact points; the height of the support column 2 can be adjusted by rotating the knob 7.

[0031] Figure 3 The diagram shows the coordinate system of the turntable, where the solid circle represents the plane of the inclined platform. P 1. P 2.P 3 are the support points, arranged clockwise around the circumference of the turntable; coordinate system z The shaft coincides with the rotating shaft 4 of the turntable. y The shaft includes one of the support points. P 1;

[0032] Figure 4 vectors in a 1. a 2. a 3 correspondence representation Figure 3 The tilt state of the middle platform.

[0033] Figure 5 The diagram illustrates the mathematical principle of turntable leveling: if the support column is raised... P At a height of 1, the platform generates a vector. i Inclined vectors in the same direction; if the support column is raised P 2, then the platform generates and j Inclined vectors in the same direction, and so on;

[0034] By adjusting two of the three support columns, namely the highest support column and the lowest support column, any change in the tilt vector can be generated, making it equal in magnitude and opposite in direction to the original tilt vector of the support platform, thus achieving the leveling of the rotary platform.

[0035] Specifically, the number of faces of the prism is given below. n =4, and β ab =85°, β ac =170° β ad Example of leveling operation of a three-point support turntable at 265°:

[0036] Step 1: Place an optical prism 8 in the center area of ​​the three-point support turntable 4. The optical prism 8 has four faces. Adjust the relative angle between the prism 8 and the turntable 4 so that the normal of any working face of the prism is parallel to the line connecting any turntable support point and the center of the turntable 4. Label this working face of the prism and the turntable support point as face A, face B, face C, face D, face E, face F, face G, face H, face F, face G ... P 1. Support point, determine this position as the measurement zero point;

[0037] Step Two: According to Figure 6 Rotate turntable 4 to align surface A with autocollimator 9, as shown in the left figure, so that autocollimator 9 is aligned with the measurement obtained from surface A. X The axis angle value is within the arcsecond range, at which point the measurement of the autocollimator 9 is performed. Y Axis angle i 1;

[0038] Step 3: Rotate turntable 4 clockwise, and as described in Step 2, measure the alignment of surfaces B, C, and D of the optical prism 8 with the autocollimator. Y Axis angle i 2. i 3. i 4;

[0039] Step 4: Rotate turntable 4 to align face A with autocollimator 9 again. Then, keeping turntable 4 stationary, rotate prism 8 to align face B with autocollimator 9. The position at this point is as follows: Figure 6 As shown in the right figure, and measurements were taken. Y Axis angle i 5;

[0040] Step 5: Rotate the turntable 4 to align surface C with the autocollimator 9 and take measurements. Y Axis angle i 6;

[0041] Step Six: Solve the system of equations to find the platform tilt angle. i p and tilt direction i 0,

[0042] ,

[0043] Step 7: Based on the tilt direction in Step 6 i The value of 0 is used to represent the support columns of a three-point support platform in the following three cases. P 1. P 2. P 3. Make adjustments to achieve platform balancing:

[0044] a. If i 0 is between 0° and 60° or between 180° and 240°, adjust surface A so that its normal line is aligned with the support point. P The lines connecting point 1 and the center of the turntable are parallel to each other. Rotate the turntable so that surface A is aligned with the autocollimator. After alignment, the positional relationship of the instrument setup is as follows: Figure 7 As shown in the left figure, the support column is then adjusted. P The height of 1 makes the autocollimator Y Increase in shaft angle measurement value i p cos i 0- 0.57735 i p sin i 0; then adjust surface A so that its surface normal is perpendicular to the support point. P 3. The line connecting the center of the turntable and the center of the circle are parallel. Rotate the turntable so that surface A is aligned with the autocollimator. After alignment, the positional relationship of the instrument setup is as follows: Figure 7 As shown in the right figure, adjust the support column. P The height of 3 makes the autocollimatorY The measured shaft angle increased by -1.15470°. i p sin i 0;

[0045] b. If i 0 is between 60° and 120° or 240° and 300°. Adjust surface A as described in a and perform measurements with the autocollimator. First, adjust the support column. P The height of 2 makes the autocollimator Y The shaft angle measurement value increased - i p cos i 0+ 0.57735 i p sin i 0, then adjust the support column. P The height of 3 makes the autocollimator Y The measured shaft angle increased by -0.57735 degrees. i p sin i 0- i p cos i 0;

[0046] c. If i 0 is between 120° and 180° or between 300° and 360°. Adjust surface A as described in a and perform measurements with the autocollimator. First, adjust the support column. P The height of 1 makes the autocollimator Y Increase in shaft angle measurement value i p cos i 0+ 0.57735 i p sin i 0, then adjust the support column. P The height of 2 makes the autocollimator Y The measured shaft angle increased by 1.15470°. i p sin i 0;

[0047] Taking the platform tilt state as ( i p , i To further illustrate step seven, let's take (0) = (100″, 0°) as an example: Since the tilt direction is 0°, it belongs to case a. First, make the normal of face A of the prism parallel to... P Place the line connecting point 1 and the center of the circle, then rotate the turntable so that face A is aligned with the autocollimator. Assume the autocollimator is not leveled. Y The axis angle value is iy Then adjust P The height of point 1 makes the autocollimator Y The axis angle becomes i y + i p cos i 0- 0.57735 i p sin i 0= i y Leveling can be achieved by adding 100″.

Claims

1. A leveling method for a three-point supported turntable based on autocollimator measurement, characterized in that, including the following steps: Step 1: Place an optical prism in the center region of a turntable supported by three points. The optical prism has a total of n One side, n ≥ 3; Adjust the relative angle between the prism and the turntable so that the normal line of any working face of the prism is parallel to the line connecting any turntable support point and the center of the turntable. Denote this working face of the prism and the turntable support point as face A. P 1. Support point, determine this position as the measurement zero point; Step 2: Rotate the turntable so that surface A is aligned with the autocollimator, that is, align the autocollimator with the measurement obtained from surface A. X The axis angle value is within the arcsecond range, at which point the autocollimator is measured. Y Axis angle i 1; Step 3: Rotate the turntable clockwise, and as described in Step 2, measure the B, C...X faces of the optical prism respectively. Y Axis angle i n The X side is the first n noodle; Step 4: Rotate the turntable to align face A with the autocollimator again. Then, keeping the turntable stationary, rotate the prism to align face B with the autocollimator. At this point, measure the autocollimator. Y Axis angle i n+1 ; Step 5: Rotate the turntable so that plane C is aligned with the autocollimator. At this time, measure the autocollimator. Y Axis angle i n+2 ; Step Six: Solve the system of equations to find the platform tilt angle. i p and tilt direction i 0, ， Among them, the platform tilt angle i p This refers to the angle between the platform normal and the axis of rotation, and the direction of tilt. i 0 refers to the angle between the projection of the line connecting the highest and lowest points of the platform and the inner normal of surface A at the zero measurement point onto the plane perpendicular to the rotation axis. f a This refers to the perpendicularity error of face A of the prism relative to the base of the prism, and so on. β ab This represents the angle between the normals of surface A and surface B, which is the central angle corresponding to the two working surfaces, and so on. Step 7: Based on the tilt direction in Step 6 i The value of 0 is used to represent the support columns of a three-point support platform in the following three cases. P 1. P 2. P 3. Make adjustments to achieve platform leveling and support columns. P 1. P 2. P 3. Arranged in a clockwise direction: a. If i 0 is between 0° and 60° or between 180° and 240°, adjust surface A so that its normal line is aligned with the support point. P 1. The line connecting the center of the turntable and the center of the circle are parallel. Rotate the turntable so that surface A is aligned with the autocollimator, and adjust the support column. P The height of 1 makes the autocollimator Y Increase in shaft angle measurement value i p cos i 0- 0.57735 i p sin i 0; Adjust surface A so that its normal line is aligned with the support point. P 3. The line connecting the center of the turntable and the center of the circle are parallel. Rotate the turntable so that surface A is aligned with the autocollimator, and adjust the support column. P The height of 3 makes the autocollimator Y The measured shaft angle increased by -1.15470°. i p sin i 0; b. If i 0 is between 60° and 120° or 240° and 300°. Adjust surface A as described in a and perform measurements with an autocollimator. First, adjust the support column. P The height of 2 makes the autocollimator Y The shaft angle measurement value increased - i p cos i 0+ 0.57735 i p sin i 0, then adjust the support column. P The height of 3 makes the autocollimator Y The measured shaft angle increased by -0.57735 degrees. i p sin i 0- i p cos i 0; c. If i 0 is between 120° and 180° or between 300° and 360°. Adjust surface A as described in a and perform measurements with the autocollimator. First, adjust the support column. P The height of 1 makes the autocollimator Y Increase in shaft angle measurement value i p cos i 0+ 0.57735 i p sin i 0, then adjust the support column. P The height of 2 makes the autocollimator Y The measured shaft angle increased by 1.15470°. i p sin i 0.

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