JP7769348B2 - System and method for measuring inner wall of deep arrowhead workpiece - Google Patents

Description

This invention relates to a method for measuring the overall surface profile of the inner wall of a deep workpiece, specifically to a method and measurement system for measuring the overall surface profile of the inner wall of a deep workpiece by using two sensors to measure different areas of the inner wall and then joining the surface profiles together.

High-precision workpieces are widely used in precision equipment in fields such as aeronautics and nuclear physics. Thanks to their unique geometric shape and specific performance, they play a role that cannot be replaced by any other individual or assembled parts. At the same time, due to their critical location, when installed on these ultra-precision equipment, any errors in their geometry and contour will result in larger installation errors, thereby reducing the accuracy and reliability of the equipment. Therefore, as the performance requirements of these ultra-precision equipment become increasingly stringent, the requirements for high-precision workpieces also become increasingly higher. In particular, the requirements for the geometric dimensional accuracy of their inner walls and the quality of their internal contours are also becoming increasingly higher.

Currently, these deep-arrow workpieces are mainly machined using high-precision lathes. For example, when machining high-speed cutting servo (FTS), the complex control and machining processes and strict environmental requirements make the machining process susceptible to abnormal factors such as the environment and materials, which further causes defects in the deep-arrow workpieces and reduces their machining quality. Therefore, to ensure the accuracy of the geometric dimensions and consistency of the contour quality of deep-arrow workpieces, it is necessary to further improve the quality of the workpieces through secondary processing and accurately evaluate the geometric dimensions of the inner wall and the quality of the inner wall contour of deep-arrow workpieces.

However, current measurement methods mainly involve measuring the outer walls of deep workpieces. Current measurement solutions, such as CMMs, cannot measure the bottom of the inner wall due to their large probe size, and have low measurement efficiency. Optical measurement methods also cannot meet the requirements for measuring the overall surface shape of the inner wall due to optical path interference or excessively large measurement angles. Therefore, a measurement solution is needed to measure the overall surface shape of the inner wall of deep workpieces.

The objective of this invention is to provide a method and measurement system for measuring the entire surface profile of the inner wall of a deep workpiece, which requires a complete measurement of the inner wall of a deep workpiece, something that cannot be achieved with current measurement methods. This method uses two sensors to measure different areas of the inner wall, and then stitches together the surface profiles.

In order to achieve the above object, the present invention provides:
The inner wall measurement system for deep workpieces includes:

An XY positioning base is installed on a horizontal mounting surface. The XY positioning base includes an X-direction moving base that moves in the X direction and a Y-direction moving base that moves in the Y direction.

The rotation base is mounted on an XY positioning base and is used to rotate around the Z axis.

The workpiece holder is mounted on the rotating base and is used to place deep workpieces.

A vertical holder is mounted on top of which is a Z-direction moving base that moves in the Z direction.

The side measurement gauge is mounted on the Z-direction moving base and is used to measure the inner sidewalls of deep workpieces.

This is an inner wall measurement system characterized by the fact that the axial measurement gauge is installed on the Z-direction moving base and is used to measure the bottom wall of the inner wall of a deep workpiece.

Furthermore, a first spatial posture adjustment device is installed between the rotation base and the workpiece holder and is used to drive the workpiece holder to rotate in the X direction and/or the Y direction.

Furthermore, the first spatial posture adjustment device includes two first angle tables that rotate in the X direction and the Y direction, respectively.

Furthermore, two second spatial posture adjustment devices are included, which are installed on the Z-direction moving base. The side-direction measuring gauges and axial-direction measuring gauges are installed on the corresponding second spatial posture adjustment devices, respectively. The second spatial posture adjustment devices are used to drive the side-direction measuring gauges and axial-direction measuring gauges to rotate in the X direction and/or Z direction.

Furthermore, the second spatial posture adjustment device includes two second angle tables that rotate in the X direction and the Z direction, respectively.

Furthermore, all of the side and axial measuring gauges include a measuring bar and a measuring ball installed at the end of the measuring bar.

The method for measuring the inner wall of a deep-arrow high workpiece is used in the system for measuring the inner wall of a deep-arrow high workpiece, and includes the following steps:

Step (1) Calibrate the side-facing measuring instrument so that it is perpendicular to the axial-facing measuring instrument.

Step (2) Calibrate the workpiece holder so that the deep arrow height workpiece is horizontal.

Step (3) Measure the surface shape of the side wall of the inner wall of the deep-arrow-tall workpiece by moving the side measuring instrument along the generatrix of the deep-arrow-tall workpiece, butting up against the inner wall of the deep-arrow-tall workpiece. Measure the surface shape of the bottom wall of the inner wall of the deep-arrow-tall workpiece by moving the axial measuring instrument along the generatrix holder of the deep-arrow-tall workpiece to the bottom wall of the inner wall of the deep-arrow-tall workpiece axis.

Step (4) The surface shape of the inner wall's side wall and the surface shape of the inner wall's bottom wall are joined together to obtain the surface shape of the complete deep-arrow workpiece.

Furthermore, in step (1), the spatial tilt angle of the side-directed measuring gauge or the axial-directed measuring gauge is calibrated based on a standard ball, and this step (1) includes the following steps:

Step (1.1) Place the standard ball in the workpiece holder.

Step (1.2) Find the first reference plane, which is the center plane of the standard ball, and make the first reference plane parallel to a plane in the three-dimensional coordinate system.

Step (1.3) Drive the side or axial measuring instrument so that it abuts against the outer contour of the first reference surface and moves linearly along the outer contour of the first reference surface. As the side or axial measuring instrument moves, record the point where the measured value is smallest and a second position a certain distance away from the first position, and record the smallest measured value and the measured value, respectively.

Furthermore, the calculation method for step (1.4) includes the following:

Furthermore, step (1) also includes measuring the roundness of the ball in a standard ball measurement side or shaft measurement gauge, and step (1) includes the following steps:

Step (1.6) Place the standard ball in the workpiece holder.

Step (1.7) Find the second reference plane, which is the center plane of the standard ball, and make the second reference plane parallel to a plane in the three-dimensional coordinate system.

Step (1.8) Drive the side or axial measuring instrument so that it abuts against the outer contour of the second reference surface, and move linearly along the outer contour of the reference surface. As the side or axial measuring instrument moves, record the point where the measured value is smallest and a second position a certain distance away from the first position, and record the smallest measured value and the measured value, respectively.

Furthermore, the calculation method in step (1.9) includes the following:

Furthermore, step (2) includes calibrating the workpiece holder spatial tilt angle in the side-direction measuring instrument or axial-direction measuring instrument after calibration, and step (2) includes the following:

Step (2.1) Place the deep workpiece in the workpiece holder.

Furthermore, step (4) includes the following: According to the coordinate relationship between the surface shape of the side wall of the inner wall and the surface shape of the bottom wall of the inner wall, a transformation matrix is determined to the coordinates of the two surfaces in the overlapping area between the two surfaces. Then, the coordinate transformation is performed on the entire measurement surface shape to obtain the entire surface shape of the inner wall of the deep workpiece.

Compared to conventional technology, this invention has the following outstanding technical advantages:

This patent uses a side-direction measuring gauge and an axial-direction measuring gauge together to measure the wall shape of the inner wall of a deep workpiece. The measurement structure and method are not affected by light, and it can also measure a variety of deep workpieces with different dimensions. In addition, this patent uses a 6-DOF platform to calibrate the workpiece holder, the side-direction measuring gauge, and the front step of the axial measuring gauge, effectively increasing the accuracy of deep workpiece measurement.

FIG. 1 is a structural image diagram of the inner wall measurement system. FIG. 2A is an image diagram showing how to calibrate the spatial tilt angle of a side-facing measurement meter. FIG. 2B is an image diagram of calibrating the spatial tilt angle of the axial measurement gauge. FIG. 3A is an image diagram of measuring the roundness of a measurement ball of a side-facing measuring instrument. FIG. 3B is an image diagram of measuring the roundness of the ball measured by the shaft measurement meter. FIG. 4 is an image diagram of the measurement results of the ball roundness. FIG. 5A is a top view of the side measurement gauge calibrating the spatial tilt angle of the workpiece holder. FIG. 5B is a stereoscopic image diagram of the side measurement gauge calibrating the spatial tilt angle of the workpiece holder. FIG. 6 is an image diagram of the process for measuring the inner wall of a deep workpiece. FIG. 7A is an image diagram of a side-facing measuring instrument inspecting the inner wall surface of a deep workpiece. FIG. 7B is an image diagram of an axial measuring instrument inspecting the inner wall surface of a deep workpiece.

The present invention will be explained in detail in the following embodiments.

An embodiment of the present invention relates to a method and measurement system for measuring the overall surface profile of the inner wall of a deep-sea workpiece, using two sensors to measure different areas of the inner wall and then joining the resulting surface profiles. It is applicable to fields such as information and electronics, aeronautics, new energy, and biomedicine, where ultra-precision processing and measurement products are used as key components.

In this embodiment, the inner wall system for a deep workpiece includes the following:

The workpiece holder (108) is used to place the deep workpiece (109).

The side measurement gauge (111) is used to measure the side walls of the inner wall of the deep workpiece (109).

The axial measuring gauge (112) is used to measure the bottom wall of the inner wall of the deep workpiece (109).

The 6-DOF platform has the workpiece holder (108), side measurement gauge (111), and axial measurement gauge (112) mounted on it, and drives the workpiece holder (108) to move 6-DOF relative to the side measurement gauge (111) or axial measurement gauge (112).

In this patent, the 6-DOF platform includes a horizontal mounting surface (103) and a vertical holder (101). The horizontal mounting surface (103) is used to mount a workpiece holder (108). The vertical holder (101) is used to mount a lateral measuring gauge (111) and an axial measuring gauge (112).

Specifically, as shown in Figure 1, a horizontal board is placed on the horizontal support surface (103), and from bottom to top, the board is mounted with an X-direction moving base (105), a Y-direction moving base (104), a rotation base (106), a first spatial posture adjustment device (107), and the workpiece holder (108). Specifically, the X-direction moving base (105) is a sliding device in the X direction, the Y-direction moving base (104) is a sliding device in the Y direction, and the rotation base (106) is installed on the Y-type sliding device, and each drives the workpiece holder (108) to move in the X direction, move in the Y direction, and rotate in the Z direction. The first spatial posture adjustment device (107) is divided into two overlapping first angle tables. The workpiece holder (108) is installed on the corresponding first angle table. The two first angle tables are used to rotate the workpiece holder (108) around the X and Y directions, respectively.

The vertical holder (101) is placed next to the horizontal support surface (103) and includes a horizontal board and a vertical board installed vertically. A Z-direction moving base (102) and two second spatial posture adjustment devices (110) are installed on the vertical board. The two second spatial posture adjustment devices (110) are each equipped with the side-direction measuring device (111) and the axial-direction measuring device (112). The Z-direction moving base (102) is specifically a Z-direction sliding device, and two second spatial posture adjusting devices (110) are installed on the Z-direction sliding device, so that when the Z-direction sliding device operates, the side measuring gauge (111) and the axial measuring gauge (112) move up and down. By changing the height of the side measuring gauge (111) and the axial measuring gauge (112), the relative position of the workpiece holder (108) to the side measuring gauge (111) or the axial measuring gauge (112) can be changed, thereby realizing the Z-direction adjustment of the workpiece holder (108). Two second spatial posture adjusting devices (110) are installed. The two second spatial posture adjustment devices (110) respectively drive the side measurement gauge (111) and the axial measurement gauge (112) to rotate in the Z and X directions. Rotating the side measurement gauge (111) or the axial measurement gauge (112) in the Z direction rotates the workpiece relatively. The second spatial posture adjustment device (110) specifically includes two second angle tables that rotate in the X and Z directions, respectively. The vertical holder (101), horizontal support surface (103), and vertical holder (101) are aligned with the part on the horizontal support surface (103), achieving 6-DOF adjustment of the workpiece holder (108).

In this patent, the side measurement gauge (111) collects data by hitting the side wall of the inner wall of the deep-arrow workpiece (109). At its end, there is a hitting bar that contacts the inner wall of the deep-arrow workpiece (109), and the bar shakes or expands in response to changes in the shape of the side wall of the inner wall of the deep-arrow workpiece (109). The side measurement gauge (111) collects data after the hitting bar shakes or expands in different situations, thereby representing the shape of the side wall of the inner wall of the deep-arrow workpiece (109). Similarly, in this patent, the axial measurement gauge (112) collects data by hitting the deep-arrow workpiece (109). At its end, there is a hitting bar that contacts the inner wall of the deep-arrow workpiece (109), and the bar expands and contracts in response to changes in the shape of the bottom wall of the inner wall of the deep-arrow workpiece (109). The side measuring gauge (111) collects data after the abutting bar expands and contracts under different conditions, thereby representing the shape of the bottom wall of the inner wall of the deep workpiece (109). Additionally, measuring balls (202) are installed at the ends of all abutting bars, ensuring smooth abutment between the side measuring gauge (111) and the inner wall of the deep workpiece (109). Therefore, by installing the measuring balls (202), the data read by the side measuring gauge (111) and the axial measuring gauge (112) is the data from the center of the measuring ball (202) to the other end of the abutting bar.

In this patent, before measuring the deep workpiece (109), the 6-DOF platform must be calibrated to ensure accuracy. The workpiece holder (108), side measurement gauge (111), and axial measurement gauge (112) are all vertically and horizontally aligned. After all calibrations are completed, measurement of the inner wall of the deep workpiece (109) begins. The method includes the following: Measure the surface shape of the side wall of the inner wall of the deep workpiece (109) by moving the side measurement gauge (111) along the generatrix of the deep workpiece (109) and abutting against the side wall of the inner wall of the deep workpiece (109). Measure the surface shape of the bottom wall of the inner wall of the deep workpiece (109) by moving the axial measurement gauge (112) along the generatrix holder of the deep workpiece (109) to the bottom wall of the inner wall of the deep workpiece (109). The surface shape of the inner wall's side wall and the surface shape of the inner wall's bottom wall are connected to obtain the complete surface shape of the deep workpiece (109). The connecting method can be done by connecting the two measured surface shapes using a point cloud division algorithm (Concatenate).

Therefore, this patent also includes a method for calibrating inner wall measurements on a deep workpiece (109). This calibration method includes the following steps:

Step (1) Calibrate the side-direction measuring gauge (111) and the axial-direction measuring gauge (112) so that they are perpendicular.

Step (2) Calibrate the workpiece holder (108) so that the deep arrow height workpiece (109) is horizontal.

Here, step (1) also includes calibrating the spatial tilt angle of the side-directed measuring gauge (111) or the axial-directed measuring gauge (112) on the standard ball (201), and this step (1) includes the following steps:

Step (1.1) Place a standard ball (201) on the workpiece holder (108).

Step (1.2) Find the first reference plane, which is the center plane of the standard ball (201), and make the first reference plane parallel to a plane in the three-dimensional coordinate system.

In this embodiment, the spatial tilt angle of the side-directed measuring instrument (111) and the axial measuring instrument (112) can be adjusted to a relatively small threshold value by repeated calculations. For example, 0.1 degrees. At this point, the spatial tilt angle of the side-directed measuring instrument (111) and the axial measuring instrument (112) is adjusted to a relatively small threshold value.

Furthermore, step (1) includes the following: measuring the roundness of the measuring ball (202) in the side-direction measuring gauge (111) or the axis-direction measuring gauge (112) of the standard ball (201). This step (1) includes the following steps:

(1.6) Place the standard ball (201) in the workpiece holder (108).

(1.7) Find a second reference plane, which is the center plane of the standard ball (201), and make the second reference plane parallel to a plane in the three-dimensional coordinate system.

In this patent, a measuring ball (202) is installed on the side measuring gauge (111). When the side measuring gauge (111) measures the deep workpiece (109), the measured contour is the locus of the center of the circle of the measuring ball (202), not the contour of the deep workpiece (109). Therefore, the roundness contour of the measuring ball (202) must be inspected when the side measuring gauge (111) measures the deep workpiece (109). The inner wall contour of the deep workpiece (109) is mapped using the roundness contour of the measuring ball (202). As shown in Figure 4, under normal circumstances, the side measuring gauge (111) uses a measuring surface with an angle of only about 120 degrees during measurement. Therefore, when inspecting the roundness contour of the measuring ball (202), the need for the work can be met by determining the surface contour of the measuring ball (202) with an angle of about 120 degrees.

Furthermore, step (2) includes calibrating the spatial tilt angle of the workpiece holder (108) using the calibrated side-direction measuring instrument (111) or axial-direction measuring instrument (112), and this step (2) includes the following:

Step (2.1) Place the deep arrow height workpiece (109) on the workpiece holder (108) and place the deep arrow height workpiece (109) directly on the workpiece holder (108).

After all calibrations are completed, measurements are taken of the inner wall of the deep arrowhead workpiece (109).

Similarly, when the axial measuring instrument (112) measures the bottom wall of the inner wall, there is a trajectory of the measuring ball.

After obtaining the generatrix loci of the continuous inner wall side wall and the continuous inner wall bottom wall, the workpiece holder (108) is rotated and measurement continues, and the surface shapes of the continuous inner wall side wall and the inner wall bottom wall are obtained, and the surface shapes of the inner wall side wall and the inner wall bottom wall are connected based on the surface shapes of the inner wall side wall and the inner wall bottom wall.

There is always an overlapping area on the bottom wall of the wall. Specifically, the overlapping area of the two surface shapes is determined according to the coordinate axes of the measured surface shapes, and the overlapping area is then connected by matching the point cloud. That is, a matrix transformation is performed based on the coordinates of the two surface shapes, and after the coordinates are confirmed and the overlapping area is overlapped, the coordinate transformation is performed on the entire surface shape of the deep arrow height workpiece (109), and the complete surface shape of the inner wall of the deep arrow height workpiece (109) is obtained.

This patent uses a side measuring gauge (111) and an axial measuring gauge (112) together to measure the inner wall shape of a deep workpiece (109). The measurement structure and method are not affected by light and can measure all types of deep workpieces (109) of different sizes. In addition, this patent drives a 6-DOF platform to perform pre-step calibration of the workpiece holder (108), side measuring gauge (111), and axial measuring gauge (112), effectively increasing the inspection accuracy of deep workpieces (109).

The above-described embodiments are relatively preferred embodiments of the present invention, and do not limit the scope of the claims of the present invention. Therefore, all modifications that achieve the same effect according to the structure, shape, and principles of the present invention must be included within the scope of the claims of the present invention.

101 Vertical holder 102 Z-direction moving base 103 Horizontal mounting surface 104 Y-direction moving base 105 X-direction moving base 106 Rotation base 107 First spatial posture adjustment device 108 Workpiece holder 109 Deep arrow height workpiece 110 Second spatial posture adjustment device 111 Side measuring gauge 112 Axial measuring gauge 201 Standard ball 202 Measuring ball

Claims (10)

1. A system for measuring an inner wall of a workpiece , comprising:
It has a horizontal placement surface,
An XY positioning base is installed on the horizontal mounting surface.
The XY positioning base includes an X direction moving base that moves in the X direction and a Y direction moving base that moves in the Y direction,
A rotation base is installed on the XY positioning base, and the rotation base is used to rotate around the Z axis ;
a workpiece holder is installed on the rotating base, and the workpiece holder is used to place a workpiece ;
A vertical holder is provided, and a Z-direction moving base that moves in the Z direction is provided on the vertical holder.
A side measuring gauge is installed on the Z-direction moving base, and the side measuring gauge is used to measure the side wall of the inner wall of the workpiece ;
An axial measuring instrument is installed on the Z-direction moving base, and the axial measuring instrument is used to measure the bottom wall of the inner wall of the workpiece ;
An inner wall measurement system, characterized in that the side measurement gauge and the axial measurement gauge use a contact measurement method . a first spatial posture adjusting device is installed between the rotation base and the workpiece holder, and the first spatial posture adjusting device rotates the workpiece holder around the X axis and/or the Y axis ;
Two second spatial posture adjustment devices are installed on the Z-direction moving base;
The side measuring gauge and the axial measuring gauge are respectively installed on the corresponding second spatial posture adjusting device;
2. The system for measuring the inner wall of a workpiece according to claim 1, wherein the second spatial posture adjusting device is used to drive the side measuring gauge and the axial measuring gauge to rotate around the X- axis and /or the Z-axis. A method for measuring an inner wall of a workpiece used in the system for measuring an inner wall of a workpiece according to claim 1 or 2, comprising:
Step (1) of calibrating a side measurement gauge so that it is perpendicular to an axial measurement gauge;
(2) calibrating the workpiece holder so that it is level with the workpiece ;
Step (3) of measuring the surface shape of the side wall of the workpiece inner wall by moving the side measuring instrument along the workpiece generatrix against the inner wall of the workpiece, and measuring the surface shape of the bottom wall of the workpiece inner wall by moving the axial measuring instrument along the workpiece generatrix holder against the bottom wall of the inner wall of the workpiece axis;
and (4) combining the surface profile of the side wall of the inner wall and the surface profile of the bottom wall of the inner wall to obtain the complete surface profile of the workpiece . The side and axial measuring instruments have measuring balls, and by abutting the measuring balls against the inner wall of the workpiece, a measuring ball locus is generated in step (3). The measuring ball locus also has point coordinates P _Ai (x _o , y _Ai , z _Ai ). The corresponding points have a slope k _Ai and a corresponding slope angle θ _Ai relative to the coordinate system. The radius of the measuring ball at the angle θ _Ai can be calculated according to the slope k _Ai and the corresponding slope angle θ _Ai . According to the corresponding mapping relationship, the point coordinates P _{Ai ′} (x ₀ ′, y _{Ai ′} , z _{Ai ′} ) of the side wall of the inner wall corresponding to the point coordinates P _Ai (x ₀ , y _Ai , z _Ai ) can be obtained. The point coordinates P _Ai ′ ( _{x 0} ', y _Ai ', z _Ai ') can be calculated,
In step (3), there is a trajectory of the measurement ball, and the trajectory of the measurement ball has point coordinates PBi( _x0 , _yBi , _zBi ), and the corresponding point has a tilt angle _θBi with respect to the coordinate system. The radius of the measurement ball at the angle _θBi can be calculated by the tilt angle _kBi and the corresponding tilt angle _θBi. According to the mapping relationship, the point coordinates PBi _' ( _x0 ', _yBi' , _zBi' ) of the side wall of the inner wall corresponding _to the point coordinates _PBi ( _x0 , _yBi , _zBi ) can be obtained. Some point coordinates _PBi ( _x0 , _yBi , _zBi ) can be mapped to the point coordinates _PBi '( _x0 ', _yBi ', _zBi ) of the side wall of the inner wall. 4. The method for measuring an inner wall of a workpiece according to claim 3, wherein the distance between the inner wall and the workpiece is calculated. The step (1) of calibrating the spatial tilt angle of the side or axial measuring instrument based on the standard ball includes:
Step (1.1) of placing a standard ball on a workpiece holder;
(1.2) finding a first reference plane, the first reference plane being the center plane of the standard ball, and making the first reference plane parallel to a plane of a three-dimensional coordinate system ;
a step (1.3) of driving a side or axial measuring instrument to contact the outer contour of the first reference surface, and moving linearly along the outer contour of the first reference surface, and recording the smallest measured value and a second position a certain distance away from the first position while the side or axial measuring instrument is moving, and recording the smallest measured value and the measured value respectively;
Step (1.4) is to calculate the spatial tilt angle _αA between the side-direction measuring instrument or the axis-direction measuring instrument and the first reference axis according to the smallest measured value and the measured value, and set the first reference axis perpendicular to the first reference plane;
Step (1.5) of driving the second spatial posture adjusting device to calibrate the angle difference between the side-direction measuring device or the axial-direction measuring device and the first reference axis according to the value of the spatial tilt angle _αA ;
4. The method for measuring an inner wall of a workpiece according to claim 3, further comprising: In the calculation method of step (1.4),
During the movement of the side or axial measuring instrument, there are a measuring edge _{ZAO OAO} at a first position, a measuring edge Z _An O _An at a second position, a right-angled triangle O _A Q _A O _An and a right-angled triangle O _An T _A P _A , the spatial tilt angle is α _A ∠ P _A O _An T _A , the value of the measuring edge Z _A0 O _A0 at the first position is S _A0 , and the value of the measuring edge Z _An O _An at the second position is S _An ,
In the right triangle O _A Q _A O _An , point O _A is the center of the standard ball, point O _An is the center of the measurement ball of the side-directed measuring meter or the axial-directed measuring meter at the second position Z _An , and point Q _A is the intersection point of the horizontal extension of point O _A and the vertical extension of point O _An ,
In the right-angled triangle O _An T _A P _A , point P _A is the intersection point of the side of the center of the measurement ball of the side-directed or axial-directed measuring instrument at the first position Z _An , which is extended vertically, and the side Z _An O _An measured at the second position, and point T _A is the perpendicular point of point O _An on the side T _A O _AO ;
Calculate ∠P _A O _An T _A according to formula (1)-(5), wherein R is the radius of the standard ball and r _A is the radius of the measurement ball;
The method for measuring an inner wall of a workpiece according to claim 5.
The step (1) includes measuring the roundness of the ball in the standard ball measuring side or shaft measuring device.
Step (1.6) of placing a standard ball in a workpiece holder;
(1.7) finding a second reference plane, the second reference plane being the center plane of the standard ball, and making the second reference plane parallel to a plane of the three-dimensional coordinate system;
Step (1.8) is to drive the side or axial measuring instrument to abut against the outer contour of the second reference surface, and move linearly along the outer contour of the second reference surface, and record the point where the measured value is smallest during the movement of the side or axial measuring instrument and a second position that is a certain distance away from the first position, and record the smallest measured value and the measured value respectively;
4. The method for measuring the inner wall of a workpiece according to claim _{3, further comprising the step (1.9) of measuring the radius r Ai of} the measuring ball at different positions by the smallest measurement value and several other measurement values, and obtaining the roundness of the measuring ball by matching the radius r Ai of the measuring ball. In the calculation method in step (1.9),
When the side or axis measuring instrument moves, there is a right-angled triangle O _A Q _Ai O _Ai . In the right-angled triangle O _A Q _Ai O _Ai , point O _A is the center of the measured ball, point O _Ai is the center of the ball measured at the second position Z _Ai , and there is a straight line O _A Z _AO passing through point O _A , and said Q _Ai is a perpendicular point to the straight line O _A Z _{AO .}
Calculate the radius r _Ai of the measuring ball according to formulas (6)-(10), characterized in that said θ _Ai is ∠O _Ai O _A Q _Ai ;
The method for measuring an inner wall of a workpiece according to claim 7.
After the calibration in step (2), the calibration of the spatial tilt angle of the workpiece holder in the side direction measuring instrument or the axial direction measuring instrument is performed by:
Step (2.1) of placing a workpiece in a workpiece holder;
The axial measurement meter is driven to move in the X direction over the height z ₁ ' of the workpiece , find the point P ₁ ' with the largest measurement value, and record its coordinate values (x ₁ ', y ₁ ', z ₁ '); the axial measurement meter is driven to move in the X direction over the height z ₂ ' of the workpiece , find the point P ₂ ' with the largest measurement value, and record its coordinate values (x ₂ ', y ₂ ', z ₂ ');
Step (2.2) of driving the axial measurement device to move in the Y direction at height z ₃ ' in the workpiece , finding point P ₃ ' with the largest measurement value, and recording its coordinate values (x ₃ ', y ₃ ', z ₃ '); driving the axial measurement device to move in the Y direction at height z ₄ ' in the workpiece, finding point P ₄ ' with the largest measurement value, and recording its coordinate values (x ₄ ', y ₄ ', z ₄ ');
Step (2.3) of calculating the tilt angle θ _α of the workpiece holder around X and the tilt angle θ _b of the workpiece holder around Y according to formulas (11) and (12);
The method for measuring an inner wall of a workpiece according to claim 3, comprising:
In the step (4),
According to the coordinate relationship between the side wall surface shape and the bottom wall surface shape of the inner wall, the overlapping area between the two surfaces determines the transformation matrix to the coordinates of the two surfaces, and then performs coordinate transformation on the entire measurement surface shape to obtain the entire surface shape of the workpiece inner wall;
The method for measuring an inner wall of a workpiece according to claim 3.