Method for measuring form and position dimensions of short arc complex part
By establishing a coordinate system using datum planes and datum elements in the measurement of complex short-circuit parts, and translating the origin to the center of the outer arc, the problem of large errors in the measurement of the form and position dimensions of complex short-circuit parts is solved, and high-precision measurement results are achieved.
Patent Information
- Application Number
- CN202511599074.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-04
- Publication Date
- 2026-02-13
AI Technical Summary
Existing technologies cannot accurately measure the geometric dimensions of complex short-circuit parts. The measurement results are often inaccurate and unreliable, mainly because the first reference outer circle of the part is only 1/3 or 1/4 of the circle, which causes the measurement coordinate system to shift.
By determining the first datum plane, the first datum element, and the second datum element, a measurement coordinate system is established. The origin of the coordinate system is then translated to the theoretical position of the center point of the outer arc to form a new fitted coordinate system for dimensional measurement.
It achieves accuracy and reliability in measuring the shape and position dimensions of parts, with a measurement error within 0.02mm and a maximum and minimum deviation of only 0.004mm for the arc R, which conforms to the parameter settings of the machining process and ensures the correctness of the measurement results.
Smart Images
Figure CN121521045A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of part measurement technology, and in particular to a method for measuring the shape and position dimensions of complex short-circuit parts. Background Technology
[0002] In the inspection of the form and position dimensions of complex short-circuit arc parts, the main measurement methods rely on contact coordinate measuring machines (CMMs) and non-contact influence measurement devices. The measurement principle of these devices is to collect multiple data points to construct the feature to be measured and establish a coordinate system for measurement. Due to the special shape of short-circuit arc complex parts, the first reference outer circle of the part is only 1 / 3 or 1 / 4 of the circle. This leads to a large error in constructing the element features from the data points during the measurement process. Furthermore, when fitting the center of the circle during measurement, because the measurement points are all within 90°, there is a significant error in fitting the center of the outer arc, causing a shift in the measurement coordinate system of the part, ultimately making the measurement results unreliable. Summary of the Invention
[0003] The purpose of this application is to provide a method for measuring the shape and position dimensions of complex short-circuit arc parts, thereby solving the problem that existing technologies cannot accurately measure the dimensions of complex short-circuit arc parts.
[0004] To achieve the above objectives, this application adopts the following technical solution:
[0005] On the one hand, this application provides a method for measuring the geometric dimensions of complex short-arc parts, including:
[0006] Based on the clamping and positioning of each machining process of the part, the first datum surface, the first datum element, and the second datum element are determined; the first datum surface is determined by the first datum element and the second datum element.
[0007] Based on the first reference plane, the first reference element, and the second reference element, determine the Z-axis direction, X or Y-axis direction, and the origin of the coordinate system to establish a measurement coordinate system;
[0008] The origin of the measurement coordinate system is translated to the theoretical position of the center point of the outer arc to obtain the position of the center of the fitted outer arc and the direction of the coordinate system, thus forming a new fitted coordinate system.
[0009] The dimensions of the part are measured according to the new fitted coordinate system.
[0010] On the other hand, this application also provides a measuring device for the shape and position dimensions of complex short-arc parts, including:
[0011] The machining datum determination module is used to determine the first datum surface, the first datum element, and the second datum element based on the clamping and positioning of each machining operation of the part; the first datum surface is determined by the first datum element and the second datum element.
[0012] The coordinate system establishment module is used to determine the Z-axis direction, X or Y-axis direction, and origin of the coordinate system based on the first reference plane, the first reference element, and the second reference element, and to establish the measurement coordinate system.
[0013] The coordinate system translation module is used to translate the origin of the measurement coordinate system to the theoretical position of the center point of the outer arc, so as to obtain the position of the center of the fitted outer arc and the direction of the coordinate system, and form a new fitted coordinate system.
[0014] The dimension measurement module is used to measure the dimensions of the part according to the new fitted coordinate system.
[0015] Based on the above technical solution, this application can achieve the following technical effects:
[0016] To address the issues of large measurement errors and unreliable results when using existing inspection resources for inspecting numerous dimensions in the industry, due to limitations in measuring tools, equipment principles, and software algorithms, this method uses the process machining datum as the primary element for establishing the part's measurement coordinate system. Then, based on the theoretical values from the design drawings, the origin of the coordinate system is translated to the theoretical position of the outer arc center, which serves as the part's center for subsequent measurements. After measurement, the remaining dimensions are verified using a reverse calculation method to ensure measurement accuracy. This method solves the problem of inspecting a large number of dimensions. It can be widely applied in the machining inspection industry. Attached Figure Description
[0017] Figure 1 This is a flowchart illustrating a method for measuring the shape and position dimensions of a complex short-arc part according to an embodiment of this application;
[0018] Figure 2 This is a schematic diagram illustrating the implementation process of a method for measuring the shape and position dimensions of complex short-arc parts according to an embodiment of this application;
[0019] Figure 3 This is a schematic diagram of part machining and clamping provided in an embodiment of this application;
[0020] Figure 4 This is a schematic diagram of the establishment of the B reference plane coordinate system according to an embodiment of this application;
[0021] Figure 5 This is a schematic diagram of the establishment of the C-datum plane coordinate system provided in an embodiment of this application;
[0022] Figure 6 This is a schematic diagram of the translation confirmation of the B reference plane coordinate system according to an embodiment of this application;
[0023] Figure 7This is a schematic diagram of the rotation of the C-reference plane coordinate system provided in an embodiment of this application;
[0024] Figure 8 This is a schematic diagram of the translation confirmation of the C-datum plane coordinate system provided in an embodiment of this application;
[0025] Figure 9 This is a schematic diagram illustrating the evaluation of the arc size of a certain type of part according to an embodiment of this application;
[0026] Figure 10 This is a schematic diagram illustrating the compliance verification of the coordinate system of a certain type of part according to an embodiment of this application;
[0027] Figure 11 This is a partial view of the dimensions of a certain model housing provided in an embodiment of this application. Detailed Implementation
[0028] The present application will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present application will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and are not to scale, and are only used to facilitate and clarify the illustration of the embodiments of the present application.
[0029] It should be noted that, in order to clearly illustrate the content of this application, several embodiments are provided to further explain the different implementations of this application. These embodiments are enumerated rather than exhaustive. Furthermore, for the sake of brevity, content mentioned in the preceding embodiments is often omitted in the following embodiments. Therefore, content not mentioned in the following embodiments can be referred to in the preceding embodiments.
[0030] Example 1
[0031] like Figure 1 The diagram shown is a flowchart illustrating a method for measuring the shape and position dimensions of a complex short-arc part according to this embodiment. Figure 2 The diagram illustrates the implementation process of the method for measuring the geometric dimensions of complex short-circuit arc parts provided in this embodiment. The method specifically includes the following steps:
[0032] Step 102: Based on the clamping and positioning of each machining process of the part, determine the first datum plane, the first datum element, and the second datum element; the first datum plane is determined by the first datum element and the second datum element.
[0033] In one embodiment, determining the first datum plane, the first datum element, and the second datum element based on the clamping and positioning of each machining operation of the part includes:
[0034] The first reference plane is determined by clamping and positioning the first and second reference elements.
[0035] In one specific embodiment, such as Figure 3 As shown, through the study of the clamping and positioning datum for each machining process of the part, it was found that the machining of datum surface B is mainly achieved through clamping and positioning using two Φ21H7 holes. Therefore, the two Φ21H7 holes were identified as key features for establishing the coordinate system in the subsequent inspection process.
[0036] In another specific embodiment, the C-reference plane is mainly clamped and positioned using holes Φ56H7 and Φ41H7. Therefore, holes Φ56H7 and Φ41H7 are identified as key features for establishing the coordinate system in the subsequent detection process.
[0037] Step 104: Determine the Z-axis direction, X or Y-axis direction, and origin of the coordinate system based on the first reference plane, the first reference element, and the second reference element, and establish the measurement coordinate system;
[0038] In one embodiment, the step of determining the Z-axis direction, X-axis or Y-axis direction, and origin of the coordinate system based on the first reference plane, the first reference element, and the second reference element, and establishing the measurement coordinate system, includes:
[0039] The X-axis or Y-axis direction, X-axis origin, and Y-axis origin are determined based on the first and second reference elements.
[0040] The Z-axis direction and Z-axis origin are determined based on the first reference plane.
[0041] In one embodiment, determining the X-axis or Y-axis direction, the X-axis origin, and the Y-axis origin based on the first reference element and the second reference element includes:
[0042] Construct a virtual straight line by taking the center of the first and second reference elements to determine the X-axis or Y-axis direction;
[0043] The origin of the X-axis and the origin of the Y-axis are determined by taking the midpoint between the centers of the first and second reference elements.
[0044] In one specific embodiment, such as Figure 4 As shown, the key elements for establishing the coordinate system are sequentially acquired from the B datum plane elements and two Φ21H7 holes, specifically including:
[0045] The centers of the two Φ21H7 holes are used to construct a virtual straight line to determine the X+ direction of the coordinate system (the Y direction is automatically confirmed); the midpoint of the centers of the two Φ21H7 holes is used to determine the origin of the X and Y coordinate systems; the B datum plane determines the Z+ direction and the Z origin of the coordinate system. Finally, the direction and position of the B datum plane coordinate system are determined.
[0046] In yet another specific embodiment, such as Figure 5As shown, the C datum plane, Φ56H7 hole, and Φ41H7 hole were sequentially acquired as key elements for establishing the coordinate system, specifically including:
[0047] The virtual straight lines constructed from the centers of the Φ56H7 and Φ41H7 holes determine the X+ direction of the coordinate system (the Y direction is automatically confirmed); the C datum plane determines the Z+ direction and the Z origin of the coordinate system; the Φ56H7 hole determines the X and Y origins of the coordinate system. Finally, the direction and position of the C datum plane coordinate system are determined.
[0048] Step 106: Translate the origin of the measurement coordinate system to the theoretical position of the center point of the outer arc to obtain the position of the center of the fitted outer arc and the direction of the coordinate system, thus forming a new fitted coordinate system;
[0049] In one embodiment, translating the origin of the measurement coordinate system to the theoretical position of the center point of the outer circular arc to obtain the fitted center position of the outer circular arc and the orientation of the coordinate system includes:
[0050] The theoretical position of the center point of the outer arc is obtained by using the theoretical values of the design drawings;
[0051] Calculate the theoretical deviation between the origin of the measurement coordinate system and the theoretical position of the center point of the outer circular arc;
[0052] Based on the theoretical deviation, the measurement coordinate system is translated to obtain the position of the center of the fitted outer arc and the direction of the coordinate system.
[0053] In one embodiment, calculating the theoretical deviation between the origin of the measurement coordinate system and the theoretical position of the center point of the outer circular arc includes:
[0054] The theoretical deviation between the origin of the measurement coordinate system and the center point of the outer arc is calculated using a three-dimensional model.
[0055] In one specific embodiment, such as Figure 6 As shown, the theoretical relationship (X,Y) between the origin (midpoint) of the B reference plane measurement coordinate system and the center point of the outer arc is calculated using a three-dimensional model as (0,58.6899). Therefore, the coordinate system needs to be translated by 58.6899 along the Y+ direction to fit the position of the center of the outer arc.
[0056] In one embodiment, before translating the origin of the measurement coordinate system to the theoretical position of the center point of the outer arc to obtain the fitted center position of the outer arc and the coordinate system direction, the method further includes:
[0057] Obtain the deviation between the X-axis direction of the measurement coordinate system and the X-axis direction of the coordinate system in the design drawing;
[0058] Based on the deviation value of the coordinate system along the X-axis direction from the design drawings, the measurement coordinate system is rotated along the Z-axis to align the coordinate system direction.
[0059] In yet another specific embodiment, such as Figure 7 As shown, calculations using a 3D model show that the X+ direction of the C datum plane coordinate system is offset by 45.79945 from the X+ direction of the design drawing coordinate system. Therefore, the coordinate system needs to be rotated 45.7994 along the Z-axis to correct the coordinate system direction.
[0060] like Figure 8 As shown, the positional relationship (X,Y) between the origin (midpoint) of the C reference plane coordinate system and the center point of the outer arc is calculated using a three-dimensional model as (0,109). Therefore, the coordinate system needs to be translated 109 in the Y+ direction to fit the position of the center of the outer arc.
[0061] Step 108: Measure the dimensions of the part according to the new fitted coordinate system.
[0062] In one specific embodiment, by establishing the coordinate system described above, fitting the center of the outer arc, and determining the XYZ directions for measurement, the subsequent part size acquisition and size evaluation work can be completed in accordance with normal procedures.
[0063] 1. Evaluation of the size of the arc
[0064] Because traditional methods of evaluating the dimensions of circular arcs suffer from significant errors in directly fitting the arc elements due to the characteristics of short arcs, this paper leverages the advantage of the coordinate system origin mentioned above. Five to seven points are evenly collected on the arc surface (one point every 20°). The straight-line distance from the coordinate system origin to each measurement point is directly calculated, forming a measurement interval. The radius R is then indirectly determined. Figure 9 As shown.
[0065] 2. Roundness dimensions of the arc
[0066] After measuring 5-7 R values using the above method, the maximum difference between the maximum and minimum values is the measured value of the roundness of the arc.
[0067] 3. Evaluation of linear distance dimensions
[0068] Under the above coordinate system, the linear distance dimension measurement result of the part can be obtained by directly calculating the actual measured values of the X, Y, and Z coordinates of each element.
[0069] In one embodiment, prior to measuring the dimensions of the part according to the new fitted coordinate system, the method further includes:
[0070] The actual measurement values of the holes at multiple different locations were obtained under the new fitted coordinate system;
[0071] Based on the actual measured values and corresponding theoretical coordinate values of the holes at multiple different locations, the deviation values of the holes at multiple different locations in the new fitted coordinate system are calculated respectively.
[0072] Find the linear dimensional tolerance with the highest requirements in the design drawings. If the deviation values of the holes at multiple different positions in the new fitted coordinate system are all less than the linear dimensional tolerance, then it proves that the new fitted coordinate system meets the measurement requirements.
[0073] In one specific embodiment, among the dimensions to be measured, the distance dimension related to the origin of the coordinate system is identified, and the actual value of this dimension is measured, as follows: Figure 10 As shown.
[0074] In addition to the holes used in the first and second datum elements, two (or more) holes are found at different positions in this coordinate system as evidence that the coordinate system is correctly established.
[0075] The proof method is as follows: Given that the theoretical coordinates (X, Y) of the two holes should be (-26.5, -101) and (24, -88.5), the actual measured values (X1, Y1) of the two holes are directly calculated in the above-mentioned translated coordinate system. The deviation value ф of the two holes in this coordinate system is then calculated: ф=2×√(X-X1) 2 +(Y-Y1) 2
[0076] Find the linear dimensional tolerance ∈ with the highest requirement in the design drawings. Taking the above figure as an example, ∈ = 0.03 (outer circle radius). If both of the determined holes (or multiple holes) satisfy ф < ∈, it proves that the coordinate system meets the requirements of this measurement.
[0077] In one embodiment, such as Figure 11 As shown, by comparing data from the original measurement method and the previous measurement method, it is concluded that the center of the outer arc fitted using the machining datum can accurately represent the center position of the part, and can be used to detect the positional dimensions related to the center of the outer arc in the design drawings. Detailed data is shown in Table 1.
[0078] Table 1. Comparison of Measurements and Results
[0079]
[0080]
[0081] Analysis of the measurement data revealed that directly establishing a coordinate system using the center point of the arc resulted in significant deviations in the fitting of the arc center point, leading to deviations of over 0.05mm in various geometric dimensions, with the arc radius (R) deviation reaching 0.3mm. This made the measurement results unsuitable for assessing part quality. However, using a coordinate system fitted from the machining datum to measure various geometric dimensions resulted in errors within 0.02mm. Furthermore, the calculated positions of all points on the arc radius (R) using polar radius conversion were within the acceptable range, with the maximum and minimum deviations of R being only 0.004mm. This aligns with the parameter settings and equipment error range of the machining process, proving the reliability of the measurement method. Theoretical verification using a reverse calculation method, where all parameters were measured using a fixed parameter as the measurement datum and all results were normal, demonstrates the validity of the inspection method. Therefore, this method effectively solves the challenge of inspecting the position, shape, and dimensions of short arc-shaped parts.
[0082] In summary, addressing the issues of large measurement errors and unreliable results when using existing inspection resources for inspecting numerous dimensions in the industry, due to limitations in measuring tools, equipment principles, and software algorithms, this method employs the process machining datum as the primary element for establishing the part's measurement coordinate system. Then, using the theoretical values from the design drawings, the origin of the coordinate system is translated to the theoretical position of the outer arc center, serving as the part's center for subsequent measurements. After measurement, the remaining dimensions are verified using a reverse calculation method to ensure measurement accuracy. This method solves the problem of inspecting a large number of dimensions. It can be widely applied in the machining inspection industry.
[0083] Example 2
[0084] This embodiment provides a device for measuring the shape and position dimensions of complex short-circuit parts. The device includes:
[0085] The machining datum determination module is used to determine the first datum surface, the first datum element, and the second datum element based on the clamping and positioning of each machining operation of the part; the first datum surface is determined by the first datum element and the second datum element.
[0086] The coordinate system establishment module is used to determine the Z-axis direction, X or Y-axis direction, and origin of the coordinate system based on the first reference plane, the first reference element, and the second reference element, and to establish the measurement coordinate system.
[0087] The coordinate system translation module is used to translate the origin of the measurement coordinate system to the theoretical position of the center point of the outer arc, so as to obtain the position of the center of the fitted outer arc and the direction of the coordinate system, and form a new fitted coordinate system.
[0088] The dimension measurement module is used to measure the dimensions of the part according to the new fitted coordinate system.
[0089] In summary, addressing the issues of large measurement errors and unreliable results when using existing inspection resources for inspecting numerous dimensions in the industry, due to limitations in measuring tools, equipment principles, and software algorithms, this device employs the process machining datum as the primary element for establishing the part's measurement coordinate system. Then, using the theoretical values from the design drawings, the origin of the coordinate system is translated to the theoretical position of the outer arc center, serving as the part's center for subsequent measurements. After measurement, the remaining dimensions are verified using a reverse calculation method, ensuring the accuracy of the measurements. This solves the problem of inspecting a large number of dimensions. This device can be fully utilized in the machining inspection industry.
[0090] Example 3
[0091] In another feasible embodiment, this embodiment provides a measuring device for the shape and position dimensions of complex short-arc parts, the device specifically including:
[0092] A processor; and a memory arranged to store computer-executable instructions, which, when executed, cause the processor to perform the steps as described in any of the above method embodiments.
[0093] Example 4
[0094] In another feasible embodiment, this embodiment provides a measurement and storage medium for the shape and position dimensions of complex short-arc parts, the storage medium specifically including:
[0095] The storage medium stores a measurement and processing program for the shape and position dimensions of complex short-circuit arc parts. When the processor executes the measurement and processing program for the shape and position dimensions of complex short-circuit arc parts, it implements the steps as described in any of the above method embodiments.
[0096] The above description is merely an embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of this application should be included within the scope of the claims of this application.
Claims
1. A method for measuring the geometric dimensions of complex short-circuit arc parts, characterized in that, include: Based on the clamping and positioning of each machining process of the part, determine the first datum plane, the first datum element, and the second datum element; The first reference plane is determined by the first reference element and the second reference element; Based on the first reference plane, the first reference element, and the second reference element, determine the Z-axis direction, X or Y-axis direction, and the origin of the coordinate system to establish a measurement coordinate system; The origin of the measurement coordinate system is translated to the theoretical position of the center point of the outer arc to obtain the position of the center of the fitted outer arc and the direction of the coordinate system, thus forming a new fitted coordinate system. The dimensions of the part are measured according to the new fitted coordinate system.
2. The method according to claim 1, characterized in that, The step of determining the first datum plane, the first datum element, and the second datum element based on the clamping and positioning of the part according to each machining process includes: The first reference plane is determined by clamping and positioning the first and second reference elements.
3. The method according to claim 1, characterized in that, The step of determining the Z-axis direction, X-axis or Y-axis direction, and origin of the coordinate system based on the first reference plane, the first reference element, and the second reference element, and establishing the measurement coordinate system, includes: The X-axis or Y-axis direction, X-axis origin, and Y-axis origin are determined based on the first and second reference elements. The Z-axis direction and Z-axis origin are determined based on the first reference plane.
4. The method according to claim 3, characterized in that, The step of determining the X-axis or Y-axis direction, X-axis origin, and Y-axis origin based on the first and second reference elements includes: Construct a virtual straight line by taking the center of the first and second reference elements to determine the X-axis or Y-axis direction; The origin of the X-axis and the origin of the Y-axis are determined by taking the midpoint between the centers of the first and second reference elements.
5. The method according to claim 1, characterized in that, The step of translating the origin of the measurement coordinate system to the theoretical position of the center point of the outer arc to obtain the fitted position of the outer arc center and the coordinate system direction includes: The theoretical position of the center point of the outer arc is obtained by using the theoretical values of the design drawings; Calculate the theoretical deviation between the origin of the measurement coordinate system and the theoretical position of the center point of the outer circular arc; Based on the theoretical deviation, the measurement coordinate system is translated to obtain the position of the center of the fitted outer arc and the direction of the coordinate system.
6. The method according to claim 5, characterized in that, The calculation of the theoretical deviation between the origin of the measurement coordinate system and the theoretical position of the center point of the outer circular arc includes: The theoretical deviation between the origin of the measurement coordinate system and the center point of the outer arc is calculated using a three-dimensional model.
7. The method according to claim 1, characterized in that, Before translating the origin of the measurement coordinate system to the theoretical position of the center point of the outer arc to obtain the fitted center position of the outer arc and the direction of the coordinate system, the method further includes: Obtain the deviation between the X-axis direction of the measurement coordinate system and the X-axis direction of the coordinate system in the design drawing; Based on the deviation value of the coordinate system along the X-axis direction from the design drawings, the measurement coordinate system is rotated along the Z-axis to align the coordinate system direction.
8. The method according to claim 1, characterized in that, Before performing dimensional measurements on the part according to the new fitted coordinate system, the method further includes: The actual measurement values of the holes at multiple different locations were obtained under the new fitted coordinate system; Based on the actual measured values and corresponding theoretical coordinate values of the holes at multiple different locations, the deviation values of the holes at multiple different locations in the new fitted coordinate system are calculated respectively. Find the linear dimensional tolerance with the highest requirements in the design drawings. If the deviation values of the holes at multiple different positions in the new fitted coordinate system are all less than the linear dimensional tolerance, then it proves that the new fitted coordinate system meets the measurement requirements.
9. The method according to claim 1, characterized in that, The step of measuring the dimensions of the part according to the new fitted coordinate system includes: Based on the new fitted coordinate system, multiple measurement points are uniformly collected on the arc surface of the part, and the straight-line distance from the origin of the coordinate system to each measurement point is calculated to obtain the radius of each measurement point. Calculate the maximum difference between the maximum and minimum radius dimensions of the multiple measurement points to obtain the measured value of the roundness of the part's arc.
10. A measuring device for the shape and position dimensions of complex short-arc parts, characterized in that, include: The machining datum determination module is used to determine the first datum surface, the first datum element, and the second datum element based on the clamping and positioning of each machining operation of the part. The first reference plane is determined by the first reference element and the second reference element; The coordinate system establishment module is used to determine the Z-axis direction, X or Y-axis direction, and origin of the coordinate system based on the first reference plane, the first reference element, and the second reference element, and to establish the measurement coordinate system. The coordinate system translation module is used to translate the origin of the measurement coordinate system to the theoretical position of the center point of the outer arc, so as to obtain the position of the center of the fitted outer arc and the direction of the coordinate system, and form a new fitted coordinate system. The dimension measurement module is used to measure the dimensions of the part according to the new fitted coordinate system.