A wheel hub spoke turning method

Abstract

The present invention provides a wheel hub spoke turning processing method, which belongs to the field of wheel hub processing, comprising: scanning the spoke surface of a workpiece to be processed with a 3D line laser scanner, and converting it to obtain three-dimensional point cloud information in a lathe coordinate system; converting the three-dimensional point cloud information into polar coordinates to obtain point cloud polar coordinates; discretizing the target wheel spoke surface in polar coordinate form to obtain target polar coordinates, taking the Z-direction difference between each target polar coordinate and the corresponding point cloud polar coordinate as a processing allowance, and obtaining the number of processing layers according to the processing allowance and a set single cutting depth of the lathe. n For each target polar coordinate, a turning data table of size is established based on the target polar coordinate value, the number of machining layers, and the single cutting depth. Each turning data table is then imported into the interpolator of the numerical control system to control the lathe to perform turning on the workpiece to obtain the wheel hub spoke. The present invention can effectively improve machining efficiency and machining accuracy, has strong adaptability, and is less costly.

Description

Technical Field

[0001] The invention belongs to the field of wheel hub processing, and particularly relates to a wheel hub spoke turning processing method. Background Art

[0002] As key load-bearing components of a vehicle, wheel hubs and spokes face significantly increased structural complexity and precision requirements as vehicles become lighter and more high-performance. Due to the complex shapes of wheel hubs and spokes, existing turning equipment and solutions are unable to perform turning operations. Therefore, milling is currently the most common process for wheel hub and spoke processing. However, when milling technology is applied to wheel hub and spoke processing, it has the following drawbacks:

[0003] 1) Processing efficiency and tool wear issues

[0004] Existing milling processes rely on fixed tool paths and constant cutting parameters. The sticky nature of lightweight materials like aluminum and magnesium alloys accelerates tool wear (for example, a carbide tool's lifespan when machining aluminum alloy is less than 50 pieces per blade). Frequent tool changes also lead to a 20% to 30% drop in machining efficiency. Furthermore, removing excess material from the spoke hollowing pattern requires multiple layered milling operations, resulting in low material utilization (only 60% to 70%) and high energy consumption (up to 2.5 kW / h per tool).

[0005] 2) Insufficient machining accuracy of complex surfaces

[0006] Milling asymmetric spokes or irregularly shaped surfaces requires multi-axis CNC lathes. However, traditional processes rely on empirical programming for tool path planning, which can easily lead to localized overcutting or residual stock (error ≥ 0.15mm), affecting dynamic balancing performance. For example, the curved surface of the spoke-rim mating surface often requires manual polishing and correction after milling, increasing process time and cost. Furthermore, thin-walled structures (≤3.2mm) are prone to chatter due to uneven cutting force distribution, resulting in excessive surface roughness (Ra > 3.2μm) and reduced fatigue life.

[0007] 3) The contradiction between multi-variety adaptability and cost

[0008] The demand for customized wheel hubs has led to a wide variety of spoke pattern designs. However, traditional milling requires individual programming and fixture adjustment for each pattern (debugging a single pattern takes ≥4 hours), resulting in a surge in costs for small-batch production. While existing universal fixtures can accommodate spokes of various sizes (such as the modular gripper in patent CN215147152U), the positioning accuracy for special-shaped spokes remains insufficient (repeatability error ≥0.08mm), making it difficult to meet the micron-level tolerances required by high-end models. Summary of the Invention

[0009] The purpose of the present invention is to provide a wheel hub spoke turning method, which can effectively improve the processing efficiency and processing accuracy, has strong adaptability and lower cost.

[0010] The present invention is achieved through the following technical solutions:

[0011] A wheel hub spoke turning method comprises the following steps:

[0012] Step S1: The workpiece to be processed is mounted on the rotating spindle of the lathe. The 3D line laser scanner is mounted on the lathe. The spoke surface of the workpiece to be processed is scanned in conjunction with the rotation of the rotating spindle. When the rotating spindle rotates one angle, the 3D line laser scanner scans a set of point cloud data. When the rotating spindle rotates 360 degrees, the point cloud data can be collected. k The point cloud data is assembled, and the scan data is converted into three-dimensional point cloud information in the lathe coordinate system according to the rigid body transformation relationship between the scan coordinate system and the lathe coordinate system determined by calibration;

[0013] Step S2: converting the three-dimensional point cloud information obtained in step S1 into polar coordinates to obtain point cloud polar coordinates;

[0014] Step S3: Discretize the target spoke surface in polar coordinate form to obtain target polar coordinates. The Z-direction difference between each discretized target polar coordinate and the corresponding point cloud polar coordinate in step S2 is used as the machining allowance. The number of machining layers is obtained based on the machining allowance and the set single cutting depth of the lathe. n , where the Z direction is the axis direction of the rotating spindle;

[0015] Step S4: For each target polar coordinate, a value of The turning processing data table is imported into the interpolator of the CNC system to control the lathe to perform turning processing on the workpiece to obtain the wheel hub spokes.

[0016] Furthermore, in step S1, the lathe has an X feed axis, a Z1 feed axis, a Z2 feed axis and a rotating spindle, the Z1 feed axis and the Z2 feed axis are the axial directions of the rotating spindle, the X feed axis direction is perpendicular to the Z1 feed axis, the Z2 feed axis is arranged above the Z1 feed axis, and a plurality of turning tools arranged along the X feed axis direction are arranged at the front end of the Z2 feed axis, and the laser line of the 3D line laser scanner is perpendicular to the plane formed by the X feed axis and the Z1 feed axis.

[0017] Furthermore, in step S1, the workpiece to be processed is a universal wheel spoke casting cake prepared by high-pressure casting, and the casting cake has a center hole that can be installed on a rotating spindle.

[0018] Furthermore, in step S1, the specific process of the calibration is: a standard workpiece with known geometric features is mounted on the rotating spindle, and a standard three-dimensional point cloud of the standard workpiece is obtained by a 3D line laser scanner. X s, the theoretical point cloud of the standard workpiece recorded by the CNC system in the lathe coordinate system X m ,Pick N For the corresponding standard 3D point cloud and theoretical point cloud, the least squares method is used to optimize the rotation matrix R and translation vectors t , where the error function used by the least squares method is expressed as , X m,i For the i For the theoretical point cloud in the point cloud, X s,i For the i Standard 3D point cloud in point cloud.

[0019] Furthermore, in step S2, the coordinates of the center of the spoke surface of the workpiece to be processed are determined based on the three-dimensional point cloud information obtained in step S1 ( x c , y c , z c ), the rotation angle of the workpiece to be processed corresponding to the first set of data scanned by the 3D line laser scanner is 0°, then the point cloud in the 3D point cloud information p i The corresponding workpiece rotation angle is , then the point cloud p i The polar coordinates of ,in,( x i , y i , z i ) is the point cloud p i Coordinate values ​​in the machine tool coordinate system.

[0020] Furthermore, in step S3, the machining allowance is expressed as , the number of processing layers is expressed as ,in, The point cloud information of the target spoke surface and the point cloud p i The corresponding polar coordinate value in the z direction, ceil() is the upward rounding function.

[0021] Furthermore, in step S4, the target polar coordinates p oi Expressed as ( r oi , c oi , zoi ), then the turning processing data table corresponding to the point cloud is expressed as In turning processing, according to the second column of the turning processing data table, the rotation of the rotary spindle is controlled, the first column controls the movement of the X axis, and the third column controls the Z1 axis and Z2 axis to control the turning tool movement.

[0022] Furthermore, in step S3, the number of point cloud data sets collected by line laser scanning is k , the target spoke surface is evenly divided along the rotation angle k lines, and for each line, the number of discrete points within a set distance is calculated according to a set discrete interval, so as to correspond each discrete point to each set of point cloud polar coordinates obtained in step S2.

[0023] Furthermore, the 3D line laser scanner is connected to an industrial computer, and the industrial computer and the numerical control system are in the form of a master and slave computers, using TCP / IP communication.

[0024] The present invention has the following beneficial effects:

[0025] 1. The present invention uses a 3D line laser scanner to obtain the three-dimensional point cloud information of the spoke surface of the workpiece to be processed, converts the three-dimensional point cloud information into polar coordinates, and then obtains the machining allowance based on the z-direction difference between the target polar coordinates and the corresponding point cloud coordinates, and thus obtains the number of machining layers. n Finally, the size of A turning processing data table is generated, and the lathe is controlled according to the data table to perform turning processing on the workpiece to obtain the wheel hub spokes. In this way, turning processing replaces traditional milling processing. Through the rotation of the workpiece and the linear feed of the tool, higher dimensional accuracy (usually IT6~IT8 level) and uniform surface quality (Ra 0.8~3.2μm) are exhibited in the processing of rotating parts (such as shafts and disks). In particular, the advantages are significant in the control of symmetrical features such as roundness and cylindricity. In terms of processing efficiency, the present invention is more efficient than traditional milling and can also adapt to the design of spokes with complex patterns, thereby effectively reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described in detail below with reference to the accompanying drawings.

[0027] Figure 1 Flowchart of the present invention.

[0028] Figure 2 It is a schematic structural diagram of the lathe of the present invention.

[0029] Figure 3 Schematic diagram of the positions of the 3D line laser scanner and the wheel hub spokes of the present invention.

[0030] Figure 4 It is a schematic diagram of the positions of the turning tool and the wheel hub spokes of the present invention.

[0031] Among them, 1. Lathe; 2. Rotating spindle; 3. Wheel hub; 31. Spoke surface; 4. X feed axis; 5. Z1 feed axis; 6. Z2 feed axis; 7. Turning tool. DETAILED DESCRIPTION

[0032] like Figure 1 As shown, the hub spoke turning method includes the following steps:

[0033] Step S1: The workpiece to be processed is mounted on the rotating spindle 2 of the lathe 1. The 3D line laser scanner is mounted on the lathe 1. The spoke surface 31 of the workpiece to be processed is scanned in conjunction with the rotation of the rotating spindle 2. When the rotating spindle 2 rotates one angle, the 3D line laser scanner scans a set of point cloud data. When the rotating spindle 2 rotates 360 degrees, the point cloud data can be collected. k The point cloud data is assembled, and the scan data is converted into three-dimensional point cloud information in the lathe coordinate system according to the rigid body transformation relationship between the scan coordinate system and the lathe coordinate system determined by calibration;

[0034] More specifically, if Figures 2 to 4 As shown, the lathe 1 has three servo feed axes and one servo spindle. The three servo feed axes are X feed axis 4, Z1 feed axis 5, and Z2 feed axis 6. The servo spindle is a rotating spindle 2 (i.e. Figure 4 The C axis in the figure), the Z1 feed axis 5 and the Z2 feed axis 6 are the axis directions of the rotating spindle 2 (i.e. Figure 4 The Z axis in the figure is driven forward and backward by an ordinary motor, and the Z2 axis is driven by a high-frequency motor. The Z1 axis is responsible for positioning movement. The Z2 axis is installed on the Z1 axis workbench. The front end of the Z2 feed axis 6 is provided with multiple turning tools 7 arranged along the direction of the X feed axis 4. The direction of the X feed axis 4 is horizontally perpendicular to the Z1 feed axis 5 (i.e. Figure 4 The 3D line laser scanner's laser line is perpendicular to the plane formed by the X-axis 4 and the Z1-axis 5. The Z2-axis is responsible for coordinated machining with the X-axis and the rotary spindle 2. The 3D line laser scanner is connected to an industrial computer, which is connected to the CNC system in a master-slave configuration, using TCP / IP communication. The structural relationship between the X-axis 4, the Z1-axis 5, and the Z2-axis 6 is based on existing technology.

[0035] The workpiece to be processed is a universal wheel spoke casting cake prepared by high-pressure casting. The casting cake has a center hole that can be installed on the rotating main shaft 2. The casting cake only has a certain processing allowance. The casting cake is fixed on the rotating main shaft 2 by a clamp, wherein the specific structure of the clamp is the existing technology.

[0036] The 3D line laser scanner obtains data in the scanner coordinate system. Subsequent calculations and controls are performed in the lathe coordinate system. Therefore, calibration is required to determine the rigid body transformation relationship between the scanner coordinate system and the lathe coordinate system (i.e., the rotation matrix). R and translation vectors t The specific process of calibration is: install a standard workpiece with known geometric features (such as a calibration block with regular grooves or scales) on the rotating spindle 2, and obtain the standard 3D point cloud of the standard workpiece through a 3D line laser scanner. X s , the theoretical point cloud of the standard workpiece recorded by the CNC system in the lathe coordinate system X m ,Pick N For the corresponding standard 3D point cloud and theoretical point cloud, the least squares method is used to optimize the rotation matrix R and translation vectors t , where the error function used by the least squares method is expressed as , X m,i For the i For the theoretical point cloud in the point cloud, X s,i For the i For standard 3D point clouds in point clouds, i =1,2,..., N .

[0037] Step S2: converting the three-dimensional point cloud information obtained in step S1 into polar coordinates to obtain point cloud polar coordinates;

[0038] The coordinates of the center of the spoke surface 31 of the workpiece to be processed are determined based on the three-dimensional point cloud information obtained in step S1 ( x c , y c , z c ), the spoke surface 31 is circular, and its center coordinate is the center of the circle. The specific acquisition process is technology. Define the rotation angle of the workpiece to be processed corresponding to the first set of data scanned by the 3D line laser scanner as 0° (that is, the rotation spindle 2 does not rotate when the 3D line laser scanner scans the first set of data), then the point cloud in the 3D point cloud information p i The corresponding workpiece rotation angle is , then the point cloud p i exist XY The coordinates of the plane ( x i , y i ) can be transformed into polar coordinates In the form of, combined with the value in the Z direction, we get the point cloud p i The polar coordinates of , thus forming point cloud data P', where ( x i , y i , z i ) is the point cloud p i Coordinate values ​​in the machine tool coordinate system.

[0039] Step S3: Discretize the target spoke surface in polar coordinate form to obtain target polar coordinates, and use the z-direction difference between each discretized target polar coordinate and the corresponding point cloud polar coordinate in step S2 as the machining allowance. The number of machining layers is obtained based on the machining allowance and the set single cutting depth of lathe 1. n , where the z direction is the axis direction of the rotating spindle 2;

[0040] Specifically, according to the number of point cloud data sets collected by line laser scanning k , the target spoke surface is evenly divided along the rotation angle k For each line, the number of discrete points within the set distance is calculated at the set discrete interval, and each discrete point is associated with each set of point cloud polar coordinates obtained in step S2. In this embodiment, the X-axis moves at a speed of 0.2m / min and the discrete interval is 1ms. Therefore, 300 points can be obtained for a distance of 1mm (the set distance).

[0041] The machining allowance is expressed as , the number of processing layers is expressed as ,in, The point cloud information of the target spoke surface 31 and the point cloud p i The corresponding polar coordinate value in the z direction, ceil() is the upward rounding function.

[0042] Step S4: For each target polar coordinate, a value of The turning processing data table is imported into the interpolator of the numerical control system to control the lathe 1 to perform turning processing on the workpiece to obtain the wheel hub 3 spokes;

[0043] Target polar coordinates p oi Expressed as ( r oi , c oi , z oi), then the turning processing data table corresponding to the point cloud is expressed as In turning processing, instructions are sent in the form of table lookup. According to the second column of the turning processing data table, the rotation of the rotating spindle 2 is controlled, the first column controls the movement of the X axis, and the third column controls the Z1 axis and Z2 axis to control the movement of the turning tool 7.

[0044] The above description is merely a preferred embodiment of the present invention and therefore cannot be used to limit the scope of the present invention. In other words, equivalent changes and modifications made according to the scope of the patent application and the contents of the specification should still fall within the scope of the patent of the present invention.

Claims

1. A wheel hub spoke turning method, characterized in that: The steps include: Step S1: The workpiece to be processed is mounted on the rotating spindle of the lathe. The 3D line laser scanner is mounted on the lathe. The spoke surface of the workpiece to be processed is scanned in conjunction with the rotation of the rotating spindle. When the rotating spindle rotates one angle, the 3D line laser scanner scans a set of point cloud data. When the rotating spindle rotates 360 degrees, the point cloud data can be collected. k The point cloud data is assembled, and the scan data is converted into three-dimensional point cloud information in the lathe coordinate system according to the rigid body transformation relationship between the scan coordinate system and the lathe coordinate system determined by calibration; Step S2: converting the three-dimensional point cloud information obtained in step S1 into polar coordinates to obtain point cloud polar coordinates; Step S3: Discretize the target spoke surface in polar coordinate form to obtain target polar coordinates. The Z-direction difference between each discretized target polar coordinate and the corresponding point cloud polar coordinate in step S2 is used as the machining allowance. The number of machining layers is obtained based on the machining allowance and the set single cutting depth of the lathe. n , where the Z direction is the axis direction of the rotating spindle; Step S4: For each target polar coordinate, a value of The turning processing data table is imported into the interpolator of the CNC system to control the lathe to perform turning processing on the workpiece to obtain the wheel hub spokes.

2. A wheel hub spoke turning method according to claim 1, characterized in that: In step S1, the lathe has an X feed axis, a Z1 feed axis, a Z2 feed axis and a rotating spindle, the Z1 feed axis and the Z2 feed axis are the axial directions of the rotating spindle, the X feed axis direction is perpendicular to the Z1 feed axis, the Z2 feed axis is arranged above the Z1 feed axis, and a plurality of turning tools arranged along the X feed axis direction are arranged at the front end of the Z2 feed axis, and the laser line of the 3D line laser scanner is perpendicular to the plane formed by the X feed axis and the Z1 feed axis.

3. The wheel hub spoke turning method according to claim 1, characterized in that: In step S1, the workpiece to be processed is a universal wheel spoke casting cake prepared by high-pressure casting, and the casting cake has a center hole that can be installed on a rotating spindle.

4. A wheel hub spoke turning method according to claim 1, 2 or 3, characterized in that: In step S1, the specific process of the calibration is: a standard workpiece with known geometric features is mounted on the rotating spindle, and a standard three-dimensional point cloud of the standard workpiece is obtained by a 3D line laser scanner. X s , the theoretical point cloud of the standard workpiece recorded by the CNC system in the lathe coordinate system X m ,Pick N For the corresponding standard 3D point cloud and theoretical point cloud, the least squares method is used to optimize the rotation matrix R and translation vectors t , where the error function used by the least squares method is expressed as , X m,i For the i For the theoretical point cloud in the point cloud, X s,i For the i Standard 3D point cloud in point cloud.

5. A wheel hub spoke turning method according to claim 2 or 3, characterized in that: In step S2, the coordinates of the center of the spoke surface of the workpiece to be processed are determined based on the three-dimensional point cloud information obtained in step S1 ( x c , y c , z c ), the rotation angle of the workpiece to be processed corresponding to the first set of data scanned by the 3D line laser scanner is 0°, then the point cloud in the 3D point cloud information p i The corresponding workpiece rotation angle is , then the point cloud p i The polar coordinates of ,in,( x i , y i , z i ) is the point cloud p i Coordinate values ​​in the machine tool coordinate system.

6. The wheel hub spoke turning method according to claim 5, characterized in that: In step S3, the machining allowance is expressed as , the number of processing layers is expressed as ,in, The point cloud information of the target spoke surface and the point cloud p i The corresponding polar coordinate value in the z direction, ceil() is the upward rounding function.

7. The wheel hub spoke turning method according to claim 6, characterized in that: In step S4, the target polar coordinates p oi Expressed as ( r oi , c oi , z oi ), then the turning processing data table corresponding to the point cloud is expressed as In turning processing, according to the second column of the turning processing data table, the rotation of the rotary spindle is controlled, the first column controls the movement of the X axis, and the third column controls the Z2 axis to control the movement of the turning tool.

8. The wheel hub spoke turning method according to claim 6, characterized in that: In step S3, the number of point cloud data sets collected by line laser scanning is k , the target spoke surface is evenly divided along the rotation angle k lines, and for each line, the number of discrete points within a set distance is calculated according to a set discrete interval, so as to correspond each discrete point to each set of point cloud polar coordinates obtained in step S2.

9. A wheel hub spoke turning method according to claim 2 or 3, characterized in that: The 3D line laser scanner is connected to an industrial computer, and the industrial computer and the numerical control system are in the form of a master and a slave computer, and TCP / IP communication is adopted.

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