A method of transferring a machining reference for a part
By selecting feature points on the part and constructing and correcting the planar coordinate system, the problem of machining datum transfer when large irregular parts change positions is solved, realizing high-precision machining and equipment expansion capabilities, and reducing the difficulty of calibration.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI ELECTRIC SHMP CASTING & FORGING CO LTD
- Filing Date
- 2023-04-18
- Publication Date
- 2026-06-19
AI Technical Summary
Large, irregularly shaped parts lack easily identifiable and calibrated references during processing, making it difficult to guarantee accuracy when switching to another workstation. This is especially true when the pace of equipment upgrades cannot keep up with market demands, and conventional methods are unable to meet processing requirements.
By selecting feature points on the part, a planar coordinate system is constructed between the front and rear workstations. The latter planar coordinate system is then corrected by rotating and translating the feature points, so as to achieve synchronous transfer of the machining datum and maintain accuracy.
It ensures high-precision machining of parts when the work station changes, expands the processing capacity of ordinary equipment, reduces the difficulty of calibration when parts are transferred to a different work station, and is suitable for complex parts that do not have a unified design benchmark or are difficult to calibrate.
Smart Images
Figure CN116372639B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of mechanical manufacturing technology, and in particular to a method for transferring machining references for parts. Background Technology
[0002] With the rapid development of the national equipment manufacturing industry, the demand for large and irregular forgings is constantly increasing and gradually developing towards larger and heavier sizes. However, the equipment upgrade speed of most manufacturing enterprises is often unable to meet the ever-changing market.
[0003] For example, such as Figure 1 As shown, a large, irregularly shaped part, a key core component, is manufactured by our company in a major project. It is semi-ring-shaped with an outer diameter of approximately 10.5m (radius 5.25m) and an inner diameter of approximately 7m (radius 3.50m). The plate width is approximately 1.75m. Large gantry milling machines or bridge milling machines are mainly used for machining. However, the maximum gantry width of our existing gantry milling machines is only about 4.5m. This part cannot pass directly through the gantry, and conventional methods cannot meet the basic machining requirements of this part.
[0004] In this working condition, to machine the part, it needs to be rotated during the machining process to complete the machining of all areas. Normally, parts machined at a different station need to have easily identifiable and calibrated reference points, such as a vertical plane. However, this target part lacks such features, and it has extremely high requirements for the positional and contour accuracy of key features. Conventionally, a single-station machining solution should be used. How to ensure the accuracy of these features while the station is changing has become a significant technical challenge limiting the machining process at different stations. Summary of the Invention
[0005] To address the issue of machining datum transfer, this invention provides a method for transferring machining datum for parts. The technical solution is as follows:
[0006] A method for transferring machining references for parts, comprising:
[0007] Select at least two feature points on the part;
[0008] Construct a planar coordinate system for the front and rear workstations of the part, and mark the position of the feature points under the corresponding workstations in the corresponding planar coordinate system to form the corresponding image. The latter planar coordinate system is constructed based on any feature point.
[0009] Select the rotation center point based on the feature points, translate the previous and previous images until their rotation center points coincide, and rotate the previous image until their feature points coincide.
[0010] Based on the translated and rotated coordinate system of the previous plane, the coordinate system of the next plane is corrected, and the machining is performed using this as a reference.
[0011] In a preferred embodiment of the present invention, the coordinate system of the next plane is corrected based on the coordinates of the origin of the translated and rotated previous image in the next image and the rotation angle.
[0012] In a preferred embodiment of the present invention, it includes:
[0013] S1 selects at least two feature points on the part;
[0014] When the part is in station I, S2 sets the reference zero position of the part and constructs the corresponding first plane coordinate system, draws the first plane coordinate system, marks the position of feature points, and forms the first image;
[0015] S3 adjusts the part to position II, positions the machine tool to any feature point and sets the zero position, and constructs the corresponding second plane coordinate system. The second plane coordinate system is drawn, and the adjusted feature point position is marked to form the second image.
[0016] S4 selects the rotation center point based on the feature points, translates the first image to coincide with the rotation center point under the two work positions, and rotates it around the rotation center point to coincide with the feature points under the two work positions.
[0017] S5 corrects the second plane coordinate system based on the first plane coordinate system after translation and rotation, and uses this as the reference for machining.
[0018] In a preferred embodiment of the present invention, it further includes:
[0019] S6 repeats S1-S5 or S3-S5 as the part processing station changes.
[0020] In a preferred embodiment of the present invention, two or n feature points are selected on the part, wherein the polygon formed by the n feature points as vertices has a circumcircle.
[0021] In a preferred embodiment of the present invention, when two feature points are selected, either one of them is selected as the rotation center point.
[0022] In a preferred embodiment of the present invention, when n feature points are selected, the outer center of the n feature points is selected as the rotation center point.
[0023] In a preferred embodiment of the present invention, the previous planar coordinate system selects the reference zero position according to the design reference of the part.
[0024] In a preferred embodiment of the present invention, the feature points include hole-like structures or point-like structures.
[0025] In a preferred embodiment of the present invention, the spacing l between each feature point is ≥0.3L, where L is the maximum external length of the part.
[0026] Compared with the prior art, the beneficial effects of the present invention are:
[0027] By constructing feature points and a coordinate system, this invention ensures that the machining datum can be transferred synchronously and maintain sufficient accuracy when the part changes workstations. This guarantees that the original high requirements for positional and contour elements can be completed even when the workstation changes. It is especially suitable for parts with complex contours, no unified design datum, or datums that are difficult to calibrate. At the same time, this invention does not require part position adjustment, effectively expanding the machining capacity of ordinary equipment and greatly reducing the difficulty of adjustment when the part changes workstations. Attached Figure Description
[0028] Figure 1 This is a schematic diagram of the structure of a typical part to which this invention applies;
[0029] Figure 2 This is a schematic diagram of the first image in Example 1;
[0030] Figure 3 This is a schematic diagram of the second image in Example 1;
[0031] Figure 4 This is a schematic diagram of the first and second images after translation in Example 1;
[0032] Figure 5 This is a schematic diagram of the first and second images after rotation in Example 1;
[0033] Figure 6 This is a schematic diagram illustrating the resetting of the origin of the second planar coordinate system in Example 1;
[0034] Figure 7 This is a schematic diagram of the first and second images after translation in Example 2;
[0035] Figure 8 This is a schematic diagram of the first and second images after rotation and resetting of the origin in Example 2. Detailed Implementation
[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.
[0038] A method for transferring machining references for parts, comprising:
[0039] Select at least two feature points on the part.
[0040] A planar coordinate system is constructed for the part located at the preceding and following workstations, and the positions of feature points at each workstation are marked in the corresponding planar coordinate system to form corresponding images. The subsequent planar coordinate system is constructed based on any feature point. Preferably, the preceding image also includes a two-dimensional graphic of the part at that workstation.
[0041] Select the rotation center point based on the feature points, translate the previous and previous images until their rotation center points coincide, and rotate the previous image until their feature points coincide.
[0042] Based on the translated and rotated coordinate system of the previous plane, the coordinate system of the next plane is corrected. For example, based on the coordinates of the origin of the translated and rotated image in the next image and the rotation angle, the coordinate system of the next plane is corrected, and processing is carried out based on this.
[0043] In this method, two or n feature points are typically selected. The polygon formed by the n feature points as vertices has a circumcircle. Two feature points are generally suitable when the overall rigidity of the part is good and the feature point coordinates are accurately detected. Selecting n feature points has lower requirements for the part and feature point detection compared to two feature points, and can further reduce the deviation generated during datum transfer.
[0044] When two feature points are selected in S1, either one is chosen as the center of rotation. When n feature points are selected in S1, the circumcenter of the n feature points, i.e., the center of the circumcircle, is chosen as the center of rotation.
[0045] Preferably, the distance between each feature point l ≥ 0.3L, where L is the maximum external length of the part. This allows the magnification ratio L / l to be controlled within an appropriate range when the deviation between feature points is proportionally amplified to the entire part, thereby achieving positioning.
[0046] Feature points can be inherent to the part itself or artificially placed. Hole-like or point-like structures are preferred, as they can be simply circled during subsequent coordinate detection with minimal deviation. Hole-like structures refer to structures that appear as holes, which can be constructed artificially using a method similar to drilling a center point; point-like structures refer to structures that appear as points, which can be specific sharp points on the part.
[0047] Feature points can be selected before or after machining at station I, but without a doubt, feature points should be within the machine tool's travel range to ensure that their coordinates can be detected subsequently.
[0048] The following Examples 1 and 2 will use a typical part to which this method is applicable in the background art as an example. This part is generally semi-ring-shaped, and its structure is as follows: Figure 1 The method is illustrated in the figure. In Example 1, two feature points are selected, and in Example 2, three feature points are selected.
[0049] Example 1:
[0050] A method for transferring machining references for parts, comprising:
[0051] S1 selects two feature points on the part, namely feature point 1 and feature point 2.
[0052] When the part is in station I, S2 sets the reference zero position of the part and constructs the corresponding first plane coordinate system. The reference zero position can be selected according to the design datum of the part, but if there is no obvious design datum, it can be set arbitrarily as long as it is convenient for machining. The reference zero position of this part is preferably set at the center axis of the inner and outer arcs.
[0053] It is understandable that the establishment of a planar coordinate system requires the determination of three factors: the working plane, the vector direction of the axis, and the position of the origin. In this embodiment, the position of the origin can be determined according to the origin position of the design datum, the vector direction of the axis follows the direction of the XYZ axis of the machine tool's own coordinate system, and the working plane (Z-axis position) is determined according to the requirements.
[0054] A first planar coordinate system is drawn using drawing software or manually, and the positions of feature points are marked to form a first image. At station I, the coordinates of the feature points can be detected and plotted accordingly in the first planar coordinate system.
[0055] Preferably, such as Figure 2As shown, a two-dimensional graphic of the part in station I state is also drawn to help process engineers understand the changes in station and machining coordinate system. The two-dimensional graphic of the part can be drawn, adjusted to station 1 state, and a first plane coordinate system is constructed at the same position. The positions of two feature points are located and drawn on the two-dimensional graphic of the part.
[0056] S3 adjusts the part to position II, and positions the machine tool to any feature point as the zero point, for example, feature point 1 on the adjusted part (which can be recorded as feature point 1' at this time, and the corresponding feature point 2 after adjustment is feature point 2'). A corresponding second-plane coordinate system is constructed, and the coordinates of the adjusted feature points in the second-plane coordinate system are measured. The second-plane coordinate system is then drawn, and the positions of the adjusted feature points are calibrated. Here, since feature point 1' is the origin, only feature point 2' needs to be calibrated to form the second image, as shown below. Figure 3 As shown.
[0057] S4 selects the rotation center point based on the feature points. In this embodiment, the feature point that serves as the origin, i.e., feature point 1 (feature point 1'), is used as the rotation center point. Figure 4 As shown, the first image is translated to coincide with the rotation center point under both workstations, and as... Figure 5 As shown, the feature points of the two workstations coincide when the rotation center point is rotated to coincide, that is, feature point 2 and feature point 2' coincide.
[0058] S5 measures the coordinates of the origin of the first plane coordinate system after translation and rotation in the second plane coordinate system, as well as the angle between the first and second plane coordinate systems. The zero position is set on the machine tool with this coordinate point, i.e., the zero position is corrected, and the corresponding rotation is used to obtain the corrected second plane coordinate system. At this point, the machining reference of the original station I is completely transferred to the station II state, and station II machining is performed based on this reference.
[0059] To establish a zero position on the machine tool using this coordinate point and correspondingly rotate to obtain a corrected second planar coordinate system, the second planar coordinate system can be reset first after obtaining the corrected zero position. This involves translating the second planar coordinate system to its origin, aligning it with the zero position, and simultaneously resetting the second planar coordinate system on the image. Figure 6 As shown, the angle between the first plane coordinate system and the second plane coordinate system is the angle α between the first plane coordinate system and the reset second plane coordinate system. The angle α is measured, and the reset second plane coordinate system is obtained by rotating the plane by the corresponding angle to obtain the corrected second plane coordinate system.
[0060] S6 repeats S1-S5 or S3-S5 as the part processing station changes, realizing the synchronous transfer of processing reference throughout the entire workpiece processing process.
[0061] Example 2:
[0062] Based on Example 1, this example selects three feature points and constructs a triangle based on these three feature points. The circumcenter of this triangle, i.e., the center of its circumcircle, is used as the center of rotation. The other steps are similar to those in Example 1. Specifically:
[0063] S1 selects three feature points on the part, namely feature point 1, feature point 2 and feature point 3.
[0064] When the part is in station I, S2 sets the reference zero position of the part and constructs the corresponding first plane coordinate system.
[0065] The first plane coordinate system is drawn using drawing software or manually, and the positions of feature points are marked to form the first image.
[0066] S3 adjusts the part to position II, and positions the machine tool to any feature point to set the zero position, such as feature point 1 on the adjusted part (which can be recorded as feature point 1' at this time, the corresponding feature point 2 after adjustment is feature point 2', and the corresponding feature point 3 after adjustment is feature point 3'). Then, a corresponding second plane coordinate system is constructed, the coordinates of the adjusted feature points in the second plane coordinate system are measured, the second plane coordinate system is drawn, and the position of the adjusted feature points is marked.
[0067] S4 selects the rotation center point based on the feature points. In this embodiment, the circumcenter of the three feature points is used as the rotation center point, that is, triangles are constructed using the feature points in two coordinate systems respectively, and the circumcenter is fitted. Figure 7 As shown, the first image is translated to coincide with the rotation center point under both workstations, and as... Figure 8 As shown, the feature points of the two workstations coincide when the rotation center point is rotated around. That is, feature point 1 and feature point 1' coincide, feature point 2 and feature point 2' coincide, and feature point 3 and feature point 3' coincide.
[0068] S5 measures the coordinates of the origin of the first plane coordinate system after translation and rotation in the second plane coordinate system, as well as the angle between the first and second plane coordinate systems. The zero position is set on the machine tool with this coordinate point, i.e., the zero position is corrected, and the corresponding rotation is used to obtain the corrected second plane coordinate system. At this point, the machining reference of the original station I is completely transferred to the station II state, and station II machining is performed based on this reference.
[0069] S6 repeats S1-S5 or S3-S5 as the part processing station changes, realizing the synchronous transfer of processing reference throughout the entire workpiece processing process.
[0070] In summary, by constructing feature points and a coordinate system, this invention ensures that the machining datum can be transferred synchronously and maintain sufficient accuracy when the part changes workstations. This guarantees that the original high requirements for positional and contour elements can be completed even when the workstation changes. It is especially suitable for parts with complex contours, no unified design datum, or datums that are difficult to calibrate. At the same time, this invention does not require part position adjustment, effectively expanding the machining capacity range of ordinary equipment and greatly reducing the difficulty of adjustment when the part changes workstations.
[0071] Furthermore, it should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.
Claims
1. A method for transferring machining reference points for parts, characterized in that, include: Select at least two feature points on the part; Construct a planar coordinate system for the front and rear workstations of the part, and mark the position of the feature points under the corresponding workstations in the corresponding planar coordinate system to form the corresponding image. The latter planar coordinate system is constructed based on any feature point. Select the rotation center point based on the feature points, translate the previous and previous images until their rotation center points coincide, and rotate the previous image until their feature points coincide. Based on the translated and rotated coordinate system of the previous plane, the coordinate system of the next plane is corrected, and the machining is performed using this as a reference.
2. The part machining reference transfer method of claim 1, wherein, The coordinate system of the second plane is corrected based on the coordinates of the origin of the first image after translation and rotation in the second image and the rotation angle.
3. The part machining datum transfer method according to claim 1, characterized in that, include: S1 selects at least two feature points on the part; When the part is in station I, S2 sets the reference zero position of the part and constructs the corresponding first plane coordinate system, draws the first plane coordinate system, marks the position of the feature points, and forms the first image; S3 adjusts the part to position II, positions the machine tool to any feature point and sets the zero position, and constructs the corresponding second plane coordinate system. The second plane coordinate system is drawn, and the adjusted feature point position is marked to form the second image. S4 selects the rotation center point based on the feature points, translates the first image to coincide with the rotation center point under the two work positions, and rotates it around the rotation center point to coincide with the feature points under the two work positions. S5 corrects the second plane coordinate system based on the first plane coordinate system after translation and rotation, and uses this as the reference for machining.
4. The part machining reference transfer method of claim 3, wherein, Also includes: S6 repeats S1-S5 or S3-S5 as the part processing station changes.
5. The part machining reference transfer method of claim 1 or 3, wherein, Select two or n feature points on the part, where the polygon formed by the n feature points as vertices has a circumcircle.
6. The part machining reference transfer method of claim 5, wherein, When selecting two feature points, choose either one as the rotation center.
7. The part machining datum transfer method according to claim 5, characterized in that, When n feature points are selected, the circumcenter of the n feature points is selected as the rotation center.
8. The part machining reference transfer method of claim 1 or 3, wherein, The zero point of the previous plane coordinate system is selected based on the design datum of the part.
9. The part machining reference transfer method of claim 1 or 3, wherein, The feature points include hole-like structures or point-like structures.
10. The part machining datum transfer method according to claim 1 or 3, characterized in that, The distance between each feature point l ≥ 0.3L, where L is the maximum external length of the part.