CN115046474B - A measuring system and method for inner and outer surfaces of tubular parts - Google Patents

Abstract

The invention discloses a system and a method for measuring the inner and outer surfaces of a tubular part, wherein the system comprises: a probe assembly and a probe adjustment mechanism; the probe assembly is used for measuring the inner surface and the outer surface of the tubular piece based on the optical fiber white light interferometry principle; the probe adjusting mechanism is used for adjusting the position of the probe assembly and is connected with the extension plate; the extension plate is connected with the z-direction displacement platform, and the z-direction displacement platform drives the probe assembly to move along the positive and negative directions of the z axis by driving the extension plate; the tubular member is clamped by a chuck; the chuck is connected with the rotary table and the x-direction displacement table in sequence. The method comprises the steps of firstly, calibrating an absolute reference of an optical system, adjusting a light path and calibrating before measurement to obtain a compensation value, keeping a probe adjusting mechanism still after calibration, scanning and measuring a tubular part, compensating a measurement result according to the compensation value to generate a three-dimensional point cloud data sequence of the tubular part, and analyzing to obtain measurement data.

Description

System and method for measuring inner and outer surfaces of tubular parts

technical field

The invention belongs to the technical field of precision measurement, and in particular relates to a measurement system and method for the inner and outer surfaces of a tubular part.

Background technique

In the high-precision equipment or systems in the fields of national defense, aerospace, medicine, and optics, high-precision tubular parts are ubiquitous, and in many cases, the topography of the internal and external surfaces will have a great impact on the performance of the system . Accurate and stable measurement of the inner and outer surfaces of tubular parts can effectively determine whether the machining accuracy of parts is up to standard, and is also the basis for improving machining accuracy, which is of great significance to the precision machining of tubular parts.

In the internal and external surface measurement system of the tubular part using the rotating form of the tubular part, the eccentricity between the axis of the tubular part, the rotation axis of the turntable and the axis of the probe will cause measurement errors. Therefore, combined with the structural characteristics of the rotary part, it is simple, convenient and efficient The method to compensate the measurement error is of great value in improving the measurement accuracy of the inner and outer surfaces of tubular parts.

Contents of the invention

Aiming at the deficiencies of the prior art, the invention proposes a measurement system and method for measuring the inner and outer surfaces of a tubular member.

In order to achieve the above technical purpose, the technical solution of the present invention is as follows: the first aspect of the embodiment of the present invention provides a system for measuring the inner and outer surfaces of a tubular member, including: a probe assembly and a probe adjustment mechanism; the probe assembly is based on an optical fiber The principle of white light interferometry is to collimate the beam input by the optical fiber, deflect the collimated beam by 90° and focus it to the inner or outer surface of the tubular member, and feed back the optical signal carrying the optical path information back to the white light interferometer for processing. Distance information, to complete the measurement of the inner and outer surfaces of the tubular member; the probe adjustment mechanism is used to adjust the position of the probe assembly, and is connected with the extension plate; the extension plate is connected with the z-direction displacement platform, and the z-direction displacement platform The probe assembly is driven to move along the positive and negative directions of the z-axis by driving the extension plate; the tubular member is clamped by the chuck; the chuck is sequentially connected with the turntable and the x-direction displacement table.

Further, the probe adjustment mechanism includes a sequentially connected manual rotary table, a manual translation table, a manual angler, a pole, and a rotating mounting base; the rotating mounting base is connected to the probe assembly; the manual rotating table is connected to the Extension board connection.

Further, the rough adjustment range of the manual rotary table is 360°, the fine adjustment range is ±3°, and the fine adjustment accuracy is ±5'; the stroke of the manual translation table is ±6.5 mm, the straightness is 5 μm, and the adjustment accuracy is 10 μm; the adjustment range of the manual angler is ±7°, and the adjustment accuracy is 0.1°; the coarse adjustment range of the rotary mount is 360°, the fine adjustment range is ±7°, and the fine adjustment accuracy is 10'.

Further, the probe assembly, the adjustment mechanism and the extension plate are Z-shaped; the cross-section of the extension plate is I-shaped; the z-direction translation platform is an air-floating guide rail translation platform; the turntable is an air-floating turntable.

The second aspect of the embodiment of the present invention provides a method for measuring the inner and outer surfaces of a tubular member, which is applied to the above-mentioned inner and outer surface measurement system of the tubular member, and the method includes the following steps:

S1, perform absolute reference calibration on the optical system in the probe assembly;

S2, use the calibration ring gauge to adjust the optical path and calibrate before measurement, measure the 3D point cloud data sequence of the calibration ring gauge, and perform least squares fitting on the generated 3D point cloud data sequence of the calibration ring gauge to obtain the fitted cylinder diameter , the difference between the fitting cylinder diameter and the nominal value of the ring gauge is the compensation value;

S3, actually measure the inner and outer surfaces of the tubular part of the tested part, use the compensation value obtained in step S2 to compensate the measured value, and generate the three-dimensional point cloud data of the tubular part, and perform fitting analysis on the three-dimensional point cloud data to obtain the shape tolerance and Surface roughness.

Further, the step S1 is specifically: in a state where the axis of the probe and the axis of an inner cylindrical surface whose inner diameter has been precisely calibrated maintain a relatively high degree of coaxiality, measure the inner cylindrical surface, and record the interference signal envelope The peak value corresponds to the reading of the grating scale of the scanning stage, and the reading position corresponds to the radius of the inner cylindrical surface, and subsequent measurement values are based on this radius value.

Further, the step S2 specifically includes the following sub-steps:

S201: Return all manual adjustment stages of the probe adjustment mechanism to zero;

S202: Clamp the calibration ring gauge with the chuck, and control the z-direction displacement stage and the x-direction displacement stage, so that the center point O ₁ of the probe assembly is basically in the middle section of the ring gauge in the z direction, so that the point O ₁ is on the inner surface of the ring gauge The distance is equal to the effective focal length of the probe;

S203: Adjust the light output direction of the probe by adjusting the manual rotary table, manual translation table, and manual angler, measure the ring gauge based on the optical fiber white light interferometry technology, and monitor the light intensity value of the beam returned by the measuring arm at the same time. It is enough that the intensity value reaches the threshold that can match the light intensity value of the reference arm, and try to find the position of the maximum light intensity;

S204: Make fine adjustments to the rotating mount, and observe the distance values measured by the internal and external surface measurement systems of the tubular parts until the minimum distance is found;

S205: Set the start and end height positions of the scanning measurement and the rotational speed of the turntable, control the simultaneous movement of the z-direction displacement table and the turntable, and perform helical scanning measurement on the inner surface of the ring gauge;

S206: During the scanning measurement, collect the measurement distance s value, the position value of the z-direction displacement table and the value of the turntable rotation angle. The point cloud data generation method is: the position value of the z-direction displacement table at a certain moment is the z coordinate, and the value of the turntable rotation angle at the corresponding moment The value decomposes the measurement distance into x coordinates and y coordinates, and then obtains the absolute position of a point in the point cloud data in space, and performs the same processing on the data collected at different times to obtain the 3D point cloud of the cylindrical surface in the calibration ring gauge data;

S207: Perform least square fitting on the generated point cloud data of the calibration ring gauge to obtain the diameter of the fitted cylinder, and the difference between the diameter and the nominal value of the ring gauge is a compensation value.

Further, the step S3 includes the following sub-steps:

S301: Use the chuck to clamp the tubular piece at a suitable height; by controlling the movement of the z-direction translation platform and the x-direction translation platform, the distance from the center point O ₁ of the probe assembly to the inner surface or outer surface of the tubular piece is within the distance of the probe Within the effective measurement range;

S302: Set the starting and ending height positions of the scanning measurement and the rotational speed of the turntable, control the simultaneous movement of the z-direction translation stage and the turntable, and scan and measure the inner or outer surface of the tubular part; use the compensation value obtained in step S2 to compensate the measured value to obtain a tubular 3D point cloud data of parts;

S303: performing fitting analysis on the three-dimensional point cloud data of the tubular part to obtain shape tolerance and surface roughness.

Further, the scanning measurement in the step S302 is a helical scanning measurement, a circular scanning measurement or a linear scanning measurement.

Further, in the step S303, for the part where the geometric profile of the measured surface is close to the profile of a standard geometric body, standard geometric features including circles, cylinders, and cones can be selected to perform least squares fitting on the point cloud data; and then the Quickly measure and evaluate the shape and position tolerances and surface roughness that need to be understood; The size parameters that need to be understood are measured.

The beneficial effects of the present invention are: the present invention provides a measurement system and method for the inner and outer surfaces of tubular parts, the present invention is based on the principle of optical fiber white light interferometry, and on the basis of a fast and convenient absolute reference calibration method for optical systems , through the probe assembly to achieve single-point absolute distance measurement, with the assistance of x-direction and z-direction translation stages and turntables, the single-point scanning is extended to three-dimensional scanning, and the multi-mode scanning measurement of the inner and outer surface topography of tubular parts is realized and Constructing three-dimensional point cloud data, a pre-measurement calibration method based on a calibration ring gauge is proposed, which realizes compensation for measurement errors, and can extract and evaluate the shape and position tolerances of tubular parts according to the point cloud data. The method of the present invention improves The measurement efficiency and measurement accuracy of the inner and outer surfaces of the tubular parts are improved.

Description of drawings

Fig. 1 is the schematic diagram of the mechanism of the internal and external surface measurement system of the tubular part;

Figure 2 is a schematic diagram of probe pose adjustment;

Fig. 3 is a top view of the measured state of the inner and outer surfaces;

Fig. 4 is the schematic diagram that carries out the helical scanning measurement to the inner surface of the tubular part;

Fig. 5 is a schematic diagram of performing circle scanning measurement on the inner surface of the tubular part;

Fig. 6 is a schematic diagram of performing linear scanning measurement on the inner surface of a tubular member.

Detailed ways

Reference will now be made in detail to the exemplary embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, the same numerals in different drawings refer to the same or similar elements unless otherwise indicated. The implementations described in the following exemplary examples do not represent all implementations consistent with the present invention. Rather, they are merely examples of apparatuses and methods consistent with aspects of the invention as recited in the appended claims.

A measuring system and measuring method for inner and outer surfaces of a tubular member of the present invention will be described in detail below in conjunction with the accompanying drawings. If there is no conflict, the features in the following embodiments and implementations can be combined with each other.

As shown in FIG. 1 , a system for measuring the inner and outer surfaces of a tubular member consists of a probe assembly 5 , a probe adjustment mechanism, an extension plate 1 , a z-direction displacement table 6 , a chuck 8 , an x-direction displacement table 9 and a turntable 10 .

The basic principle of probe measurement is optical fiber white light interferometry technology. The optical system structure of the space scanning Michelson interferometer based on white light source is that the light emitted by broadband white light source reaches the coupler through the optical fiber and is divided into two paths through the optical fiber. After the collimator is collimated, it is directly reflected by a plane mirror perpendicular to the incident light beam and then returns to the fiber. This path is called the reference arm. There is a scanning translation platform under the mirror that can drive the mirror in the direction of the light emitted by the collimator. Move back and forth to change the optical path of the reference arm to achieve spatial scanning. The other path of light is collimated by the collimator (the collimator is included in the probe assembly 5), and finally projected onto the surface of the object under test, and returns to the optical fiber in the original path after reflection. This path is called the measurement arm. The basic principle of the measurement is that the two beams of optical signals returned by the reference arm and the measuring arm form an interference signal through the output port of the coupler, reach the photodetector through the optical fiber, and are converted into electrical signals and collected by the data acquisition instrument, which collects them synchronously. The reading of the grating scale of the above-mentioned scanning translation stage, after extracting the peak value of the interference signal envelope, can finally obtain the reading of the grating scale of the scanning translation platform at the time corresponding to the peak value. At this time, the optical path of the reference arm and the measuring arm are equal. When measuring at different points on the surface, when the optical path of the measuring arm changes due to the change of the measured surface topography, the peak position of the interference signal envelope will also change, which can be calculated by the change of the grating ruler reading of the scanning stage corresponding to the peak position The height difference between different points on the surface to be measured.

The probe assembly 5 belongs to the end part of the measuring arm in the optical measuring system, and is mainly composed of a probe housing and optical components. The optical components integrated in the probe assembly 5 are used to collimate the light beam input from the optical fiber, deflect the collimated light beam by 90° and focus it to the inner or outer surface of the tubular member 7, and the light carrying the optical path information The signal is fed back to the white light interferometer for processing to obtain distance information. The probe housing is the carrier of the optical components. Its function is to integrate the optical components that can realize the above optical path into the probe housing. The total number of probes can be changed by increasing or decreasing the number of probe sleeves in the probe housing. Correspondingly match the extension boards 1 of different heights to meet the measurement requirements of the tubular member 7 in different height ranges. The effective focal length of the off-axis parabolic mirror has a positive and negative range, that is, the ring-shaped zone with a distance of t in Figure 3, which is the effective measurement range of the probe. According to the quality of the surface to be measured, the value of t is generally 2 to 4mm. By selecting off-axis parabolic reflectors with different effective focal lengths in the probe assembly 5 , a series of probe assemblies 5 with different focal lengths can be obtained to meet the measurement requirements of tubular members 7 with different inner diameters. Generally, the probe assembly 5 with the standard effective measurement range can be selected, and the distance from the inner point _O1 of the probe assembly 5 to the measured surface can be adjusted through the x-direction displacement table 9, so that it can be within the effective measurement range of the probe, but x The stroke of the translation stage 9 is limited. When the inner diameter of the tubular part 7 is small, the adjustment space of the x-direction translation stage 9 is insufficient, or the inner diameter of the tubular part 7 is too large, so that the distance to be adjusted exceeds the stroke of the x-direction translation stage 9. Replace the probe assembly 5 with other effective measurement ranges. For internal surface measurement, the principle of selecting the effective measurement range of the probe is that the effective focal length is less than or equal to half of the measured inner diameter, so when adjusting the distance between the probe assembly 5 and the measured surface through the x-direction displacement stage 9, only along the probe assembly 5 The outgoing light direction makes the probe assembly 5 close to the inner surface of the tubular member 7.

As shown in FIG. 1 , the probe adjustment mechanism includes a manual rotation table 2 , a manual translation table 11 , a manual angler 3 , a support rod 12 and a rotation mounting seat 4 which are sequentially connected. The coarse adjustment range of the manual rotary table 2 is 360°, the fine adjustment range is ±3°, and the fine adjustment accuracy is ±5'. The stroke of the manual translation stage 11 is ±6.5 mm, the straightness is 5 μm, and the adjustment accuracy is 10 μm. The adjustment range of the manual angler 3 is ±7°, and the adjustment accuracy is 0.1°. The coarse adjustment range of the swivel mount 4 is 360°, the fine adjustment range is ±7°, and the fine adjustment accuracy is 10'.

As shown in FIG. 2 , the position of the probe is the state when all the adjustment stages in the above-mentioned probe adjustment mechanism are at the zero position. The straight line OO ₁ is the axis of the probe, the ray with O ₁ as the end point is the light output direction of the probe, the line where the x-axis is located is the rotation axis of the manual rotary table 2, and the manual angler 3 rotates its table around the axis of the y-axis to realize the table top Swing, the ellipse in the figure is the projection on the xoz plane of the circular trajectory of the center of the table rotating around the rotation axis, and the rotation axis passes through the point O. Therefore, the final effect of the manual angler 3 is to rotate the probe around the y-axis. The straight line where the z-axis is located is the rotation axis of the rotating mount 4 , and the table top of the manual translation platform 11 translates along the positive and negative directions of the y-axis. Point O is the intersection point of the axis of the support rod 12 and the axis of the probe. When all the above-mentioned adjustment mechanisms are at zero position, the above three rotation axes take point O as the origin of the travel space Cartesian coordinate system. After the above adjustment mechanism is adjusted, the above three rotation axes will no longer form a spatial rectangular coordinate system.

The function of the manual rotating table 2 is to make all the components installed on the table rotate around its axis of rotation together, the function of the manual translation table 11 is to translate all the components installed on the table together, and the function of the manual angler 3 It is to make all the components installed on the table swing together with the table, and the function of the rotating mount 4 is to fix the probe assembly and make the probe assembly rotate around its axis.

Optical fiber white light interferometry requires the incident and reflected light to meet the corresponding requirements. Only when the light intensity of the measuring arm and the reference arm match can a more obvious interference signal that can be used to extract the interference signal envelope or fringe peak be obtained. Therefore, it is necessary to use the above adjustment mechanism to adjust the Combined fine-tuning of the probe pose is used to adjust the angle of incident and reflected light, so that conditions such as the intensity of reflected light meet the measurement requirements.

The z-direction translation platform 6 is an air bearing guide rail translation platform, which is driven by a linear motor, and can also be replaced by other forms of translation platforms. Its stroke is generally 500mm, and the positioning accuracy can reach ±0.5μm. The pitch, yaw, and roll angles are smaller than those of the mechanical guide rail turntable, and its positioning accuracy and motion error directly affect the measurement accuracy of the system. The probe assembly 5 , the adjustment mechanism and the extension plate 1 are integrally installed on the surface of the z-direction displacement table 6 , and the z-direction displacement table 6 drives the probe to move along the positive and negative directions of the z-axis by driving the extension plate 1 .

As shown in Figure 1, when the tubular member 7 is longer, a probe assembly 5 with a relatively large length and diameter is required, and the swing of the z-direction displacement table 6 may easily cause the end of the probe to be unstable. The cross section of the extension plate 1 is The purpose of the font is to improve the vibration resistance of the longboard and reduce the amplification of the vibration of the table during exercise. Viewed from the y-direction, the probe assembly 5, the adjustment mechanism and the extension plate 1 are in the shape of a font. This structure can effectively improve the stability of the probe end point _O1 , thereby reducing measurement errors and improving measurement accuracy.

The chuck 8 is a three-jaw self-centering chuck, which can also be replaced by other clamps, and its function is to clamp the tubular part 7. Since the tubular member 7 is basically a revolving body, the three jaws of the chuck 8 move synchronously, which has a centering effect on the tubular member 7, that is, ensures that the axis of the tubular member 7 has a certain degree of coaxiality with the chuck axis.

The chuck 8 is installed on the turntable 10 through an adapter plate. After the rough positioning is installed, a standard round bar should be clamped on the chuck 8, and the turntable 10 should be rotated to observe the radial runout with a dial indicator to assist fine positioning and ensure the tubular shape. The axis of the member 7 has a certain degree of coaxiality with the rotation axis of the turntable 10 to ensure that during the rotation of the tubular member 7, the angle of reflected light will not change greatly due to excessive eccentricity, which will eventually lead to the loss of some measurement points. The turntable 10 is an air-floating turntable, and other forms of turntables can also be used to replace it. The rotation angle accuracy can reach ±6arcsec, and its parameters such as end jump, radial jump, and table swing angle are smaller than those of mechanical bearing turntables, and its rotation angle accuracy and motion error, etc. It directly affects the measurement accuracy of the system, and its function is to drive the tubular member 7 to rotate.

The turntable 10 is installed on the x-direction translation stage 9, the x-direction translation platform 9 is a mechanical guide rail translation platform, the positioning accuracy can reach ±1μm, it is driven by a ball screw, and other forms of translation platforms can be used instead. Its function is to drive the measured piece to move along the positive and negative directions of the x-axis to adjust the distance between the long probe assembly point O ₁ and the inner and outer surfaces of the tubular piece 7 . The zero position of the x-direction displacement table 9 is the position where the axis of the probe coincides theoretically with the rotation axis of the turntable, and this position has been pre-calibrated when the measuring system is assembled.

The embodiment of the present invention also proposes a method for measuring the inner and outer surfaces of the tubular member based on the above-mentioned measuring system for the inner and outer surfaces of the tubular member, which specifically includes the following steps:

S1, perform absolute reference calibration on the optical system in the probe assembly (5):

As mentioned in the basic measurement principle above, the interferometer can only measure the absolute value of the relative distance, so it is necessary to designate a certain point in the light emitting direction of the probe as the absolute distance measurement reference, and the distance between point O ₁ and this point has been Know. Point O1 in Fig. ₂ is the intersection point of the probe axis and the optical axis of the outgoing light, and the arrow is a schematic representation of the outgoing light.

After the assembly of the probe assembly 5 is completed, the optical system needs to be calibrated with an absolute reference. The specific method is to keep the axis of the probe and the axis of an inner cylindrical surface whose inner diameter has been precisely calibrated to maintain a high degree of coaxiality. The inner cylindrical surface is measured, and the peak value of the envelope of the interference signal is recorded corresponding to the reading of the grating scale of the scanning translation stage. The reading position corresponds to the radius of the inner cylindrical surface. Subsequent measurements are based on this radius value. The present invention clamps the outer circle of the probe with a three-jaw self-centering chuck, and measures the inner hole of the chuck. The clamping ensures the coaxiality of the axis of the inner hole of the chuck and the axis of the probe, and the radius of the inner hole is relatively Accurate known quantity, and is limited by problems such as clamping accuracy, so this benchmark is a relatively accurate benchmark, and the calibration error is generally above 10 μm, and further corrections are still needed in the future.

As shown in Figure 3, the absolute reference is a circle centered at point _O1 , whose radius r is known. The dotted line with point O ₁ as the end point is the optical axis of the probe’s outgoing light, and the original value measured after calibration is the distance m relative to the reference (in Figure 3, the distance m ₁ between the inner surface of the tubular member and the outer surface of the tubular member surface relative to the reference distance m ₂ ), the distance s from the point O ₁ to the inner and outer surfaces of the tubular member 7 is:

s=r+m

To sum up, the absolute reference calibration of the optical system enables the measurement system to have the absolute ranging capability, and the measured value is s.

S2, use the calibration ring gauge to adjust the optical path and calibrate before measurement, measure the 3D point cloud data sequence of the calibration ring gauge, and perform least squares fitting on the generated 3D point cloud data sequence of the calibration ring gauge to obtain the fitted cylinder diameter , the difference between the fitting cylinder diameter and the nominal value of the ring gauge is the compensation value.

Before formal measurement of the DUT, optical path adjustment and pre-measurement calibration are required. Calibration before measurement requires the use of a calibration standard, specifically a grade 5 calibration ring gauge that complies with the JB/T 11233-2012 standard. , increases with the size of the ring gauge). The size of the ring gauge is selected according to the measured size of the tubular member 7 and the effective measurement range of the probe assembly 5 . The specific steps of optical path adjustment and pre-measurement calibration are as follows:

S201: Return all manual adjustment stages of the probe adjustment mechanism to zero.

S202: Clamp the ring gauge with the chuck 8, and control the movement of the z-direction displacement table 6 and the x-direction displacement table 9, so that the point O ₁ is basically in the middle section of the ring gauge in the z direction, so that the point O ₁ reaches the inner surface of the ring gauge The distance is within the effective measurement range of the probe (for combinations of probe assemblies 5 with different effective measurement ranges and calibration ring gauges of different specifications, there are pre-recorded positions of the z-direction translation stage 6 and x-direction translation stage 9 to improve optical path adjustment and the efficiency of pre-measurement calibration).

S203: By adjusting the manual rotation table 2, manual translation table 11, and manual angler 3, the light emitting direction of the probe is adjusted in a combined manner, and the ring gauge is measured based on the optical fiber white light interferometry technology using the aforementioned internal and external surface measurement system of the tubular part. Measurement, while observing the light intensity value of the beam returned by the measuring arm displayed by equipment such as an oscilloscope, the light intensity value reaches the threshold that can match the light intensity value of the reference arm, and try to find the position of the maximum light intensity.

S204: Fine-tune the rotating mounting base 4, observe the distance value measured by the system until the minimum distance is found, as shown in Figure 3, at this time the optical axis of the beam emitted by the probe passes through the center of the inner circle of the ring gauge.

S205: After setting parameters such as the start and end height positions of the scanning measurement and the rotational speed of the turntable, control the simultaneous movement of the z-direction displacement table 6 and the turntable 10, and perform helical scanning measurement on the inner surface of the ring gauge as shown in FIG. 4 .

S206: During the scanning measurement process, the system will synchronously collect the measurement distance s value, the position value of the z-direction translation platform 6 and the x-direction translation platform 9, and the rotation angle value of the turntable 10 through the data acquisition instrument. The sampling frequency is generally 30kHz. The point cloud data is generated in such a way that the position value of the translation platform in the z direction at a certain moment is the z coordinate, and the value of the rotation angle of the turntable 10 at the corresponding moment is the sum of the measured value s and the offset e of the translation platform 9 in the x direction from its zero position ( measure the inner surface) or difference (measure the outer surface) into x and y coordinates, then the absolute position of a point in the point cloud data in space is obtained, and the data collected at different times are processed in the same way, and the ring gauge The 3D point cloud data sequence of the inner cylindrical surface.

S207: Perform least squares fitting on the generated point cloud data to obtain a fitting cylinder diameter. Due to the accumulation of a series of errors such as the centering error of the chuck 8 and the installation error between the chuck 8 and the turntable 10, there is a certain offset between the axis of the cylindrical surface in the ring gauge and the axis of rotation of the turntable 10, so the measured value of a single point s fluctuates periodically in the continuous multi-turn measurement, and the cylinder diameter obtained by fitting eliminates the influence of the offset. The difference between the ring gauge nominal value D _nom and the fitted cylinder diameter D _mea is the compensation value rc, which compensates for the comprehensive error of absolute distance measurement: rc=D _nom -D _mea ; The measured value s' of is: s'=s+rc.

S3, the actual measurement of the inner and outer surfaces of the tested piece (i.e. the tubular piece 7), the compensation value obtained in step S2 is used to compensate the measured value, and the obtained three-dimensional point cloud data is fitted to the point cloud data, and the shape and position tolerance (roundness) is obtained by analysis. , cylindricity, taper, coaxiality, etc.) and surface roughness.

After the above-mentioned calibration is completed, the probe adjustment mechanism remains still, and the scanning measurement of the tubular member 7 is directly carried out. The specific steps of the scanning measurement are as follows:

S301: Use the chuck 8 to clamp the tubular member 7 at a suitable height, and control the movement of the z-direction displacement table 6 and the x-direction displacement table 9, so that the inner center point O ₁ of the probe assembly 5 reaches the inner surface or outer surface of the tubular member 7 The surface distance is within the effective measurement range of the probe;

S302: After setting the parameters such as the height and position of the beginning and end of the scanning measurement and the rotational speed of the turntable, control the simultaneous movement of the z-direction displacement table 6 and the turntable 10, and perform spiral scanning measurement on the inner surface or outer surface of the tubular member 7 as shown in Figure 4 according to requirements , or circle scanning measurement as shown in FIG. 5, or linear scanning measurement as shown in FIG.

S303: After obtaining the generated point cloud data, the point cloud data can be processed in the point cloud data processing software. For the part where the geometric contour of the measured surface is close to the contour surface of the standard geometric body, standard geometric features (circle, cylinder, cone, etc.) can be selected etc.) to perform least square fitting on the point cloud data, and then quickly measure and evaluate the shape and position tolerances (roundness, cylindricity, taper, coaxiality, etc.) and surface roughness that need to be known; For parts with complex appearance, such as irregular surface features such as threads and rifling lines, the point cloud data can be triangulated, and then the dimensional parameters that need to be understood can be measured.

The above embodiments are only used to illustrate the design concept and characteristics of the present invention, and its purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, all equivalent changes or modifications based on the principles and design ideas disclosed in the present invention are within the protection scope of the present invention.

Claims (9)

1. A system for measuring the inner and outer surfaces of a tubular member, comprising: a probe assembly (5) and a probe adjustment mechanism; the probe assembly is based on the principle of optical fiber white light interferometry, collimating the light beam input by the optical fiber, The collimated beam is deflected by 90° and focused to the inner or outer surface of the tubular member (7), and the optical signal carrying the optical path information is fed back to the white light interferometer for processing to obtain the distance information, and the internal and external inspection of the tubular member (7) is completed. Surface measurement; the probe adjustment mechanism is used to adjust the position of the probe assembly, and is connected with the extension plate (1); the extension plate (1) is connected with the z-direction displacement platform (6), and the z-direction displacement The table (6) drives the probe assembly (5) to move along the positive and negative directions of the z- axis by driving the extension plate (1); the tubular member (7) is clamped by the chuck (8); the chuck (8) and The turntable (10) and the x-direction displacement platform (9) are connected in sequence; The probe adjustment mechanism includes a manual rotary table (2), a manual translation table (11), a manual angler (3), a pole (12) and a rotating mounting base (4) connected in sequence; the rotating mounting base (4) Connected with the probe assembly (5); the manual rotating table (2) is connected with the extension plate (1); through the adjustment mechanism, the combined fine-tuning of the probe position is carried out to realize the adjustment of the angle of incident and reflected light . 2. The internal and external surface measurement system of tubular parts according to claim 1, characterized in that, the rough adjustment range of the manual rotary table (2) is 360°, the fine adjustment range is ±3°, and the fine adjustment accuracy is ±5'; The stroke of the manual translation stage (11) is ±6.5 mm, the straightness is 5 μm, and the adjustment accuracy is 10 μm; the adjustment range of the manual angler (3) is ±7°, and the adjustment accuracy is 0.1°; The coarse adjustment range of the rotating mount (4) is 360°, the fine adjustment range is ±7°, and the fine adjustment accuracy is 10'. 3. The internal and external surface measurement system of tubular parts according to claim 1, characterized in that, the probe assembly (5), the adjustment mechanism and the extension plate (1) are in the shape of a letter; the cross section of the extension plate (1) is font; the z- direction translation platform (6) is an air-floating guide rail translation platform; the turntable (10) is an air-flotation turntable. 4. A method for measuring the inner and outer surfaces of a tubular member, which is applied to the measuring system for the inner and outer surfaces of the tubular member according to any one of claims 1 to 3, wherein the method comprises the following steps: S1, perform absolute reference calibration on the optical system in the probe assembly (5); S2, use the calibration ring gauge to adjust the optical path and calibrate before measurement, measure the 3D point cloud data sequence of the calibration ring gauge, and perform least squares fitting on the generated 3D point cloud data sequence of the calibration ring gauge to obtain the fitted cylinder diameter , the difference between the fitting cylinder diameter and the nominal value of the ring gauge is the compensation value; S3, actually measure the inner and outer surfaces of the tubular part (7) under test, use the compensation value obtained in step S2 to compensate the measured value, and generate three-dimensional point cloud data of the tubular part (7), and fit the three-dimensional point cloud data The shape and position tolerance and surface roughness are obtained by analysis. 5. The method for measuring the inner and outer surfaces of a tubular member according to claim 4, wherein the step S1 is specifically: keeping the axis of the probe at a high coaxiality with the axis of an inner cylindrical surface whose inner diameter has been precisely calibrated In the state of , measure the inner cylindrical surface, record the peak value of the interference signal envelope corresponding to the reading of the grating ruler of the scanning translation stage, the reading position corresponds to the radius of the inner cylindrical surface, and the subsequent measurement values are based on this radius value. 6. The method for measuring the inner and outer surfaces of a tubular member according to claim 4, wherein said step S2 specifically comprises the following sub-steps: S201: Return all manual adjustment stages of the probe adjustment mechanism to zero; S202: Clamp the calibration ring gauge with the chuck (8), and control the z -direction displacement table (6) and the x -direction displacement table (9), so that the center point O ₁ of the probe assembly is basically in the middle section of the ring gauge in the z direction , so that the distance from the inner surface of the ring gauge at point O1 is equal _to the effective focal length of the probe; S203: By adjusting the manual rotation stage (2), manual translation stage (11), and manual angler (3), adjust the light output direction of the probe, measure the ring gauge based on optical fiber white light interferometry technology, and monitor the measurement arm at the same time Return the light intensity value of the beam. The light intensity value reaches the threshold value that can match the light intensity value of the reference arm. Try to find the position of the maximum light intensity; S204: Make fine adjustments to the rotating mount (4), and observe the distance values measured by the internal and external surface measurement system of the tubular member until the minimum distance is found; S205: Set the height and position of the beginning and end of the scanning measurement and the rotational speed of the turntable, control the simultaneous movement of the z -direction displacement table (6) and the turntable (10), and perform helical scanning measurement on the inner surface of the ring gauge; S206: During scanning measurement, collect the measurement distance s value, the position value of the z -direction translation platform (6) and the rotation angle value of the turntable (10), and the point cloud data generation method is: the position value of the z -direction translation platform at a certain moment is the z coordinate , decompose the measurement distance into x coordinates and y coordinates by using the rotation angle value of the turntable (10) at the corresponding time, then the absolute position of a point in the point cloud data in space is obtained, and the data collected at different times are processed in the same way to obtain the calibration 3D point cloud data of the cylindrical surface inside the ring gauge; S207: Perform least square fitting on the generated point cloud data of the calibration ring gauge to obtain the diameter of the fitted cylinder, and the difference between the diameter and the nominal value of the ring gauge is a compensation value. 7. The method for measuring the inner and outer surfaces of a tubular member according to claim 4, wherein said step S3 comprises the following sub-steps: S301: Use the chuck (8) to clamp the tubular member (7) at a suitable height; by controlling the movement of the z -direction translation stage (6) and the x -direction translation stage (9), the center point of the inner circle of the probe assembly (5) O ₁ The distance from the inner or outer surface of the tubular member (7) is within the effective measurement range of the probe; S302: Set the start and end height positions of the scanning measurement and the rotational speed of the turntable, control the simultaneous movement of the z-direction translation stage (6) and the turntable (10), and scan and measure the inner or outer surface of the tubular part (7); use the compensation obtained in step S2 The measured value is compensated to obtain the three-dimensional point cloud data of the tubular part (7); S303: Perform fitting analysis on the three-dimensional point cloud data of the tubular member (7) to obtain shape tolerance and surface roughness. 8 . The method for measuring the inner and outer surfaces of a tubular member according to claim 7 , wherein the scanning measurement in the step S302 is helical scanning measurement, circular scanning measurement or linear scanning measurement. 9. The method for measuring the inner and outer surfaces of a tubular member according to claim 7, characterized in that, in the step S303, for the part where the geometrical profile of the measured surface is close to the profiled surface of a standard geometric body, a circle, a cylinder, and a cone can be selected. Standard geometric features perform least square fitting on point cloud data; then quickly measure and evaluate the shape and position tolerances and surface roughness that need to be known; for complex inner and outer surface features including threads and rifles For the tested part, first triangulate the point cloud data, and then measure the size parameters that need to be known.

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