Checking method of three-section type steering shaft based on CATIA

Abstract

The invention provides a three-section type steering shaft checking method based on CATIA, and relates to the field of vehicle steering system design. In the design stage of the three-section type steering shaft, the maximum offset state of the support assembly can be simulated in CATIA software; then, the coordinate transformation function of CATIA software is used for simulating the maximum offset state of the three-section type steering shaft; whether the gap between the deviated three-section type steering shaft and the vehicle body meets the standard or not is verified in software, and if the gap meets the assembly requirement, solid components can be assembled; and if the assembly requirement is not met, the offset parameter of the support assembly in the CATIA software can be readjusted by combining the size tolerance which can be achieved in production, and the steps are repeated until verification is qualified. In this way, through the checking method, the gap between the three-section type steering shaft and the vehicle body can be accurately controlled before the vehicle is assembled; furthermore, whether the whole vehicle assembly can be smoothly carried out or not can be judged in advance through the checking method.

Description

Technical Field

[0001] The present application relates to the field of vehicle steering system design, and in particular to a CATIA-based three-section steering shaft calibration method. Background Art

[0002] The vehicle steering system is an indispensable part of the vehicle. Whether it is a fuel vehicle, an electric vehicle or a hybrid vehicle, whether it is a mechanical power steering or an electric power steering, the steering system has an irreplaceable function and status. At present, with the increasing upgrading of powertrains or motors, the cabin layout conditions are becoming more and more complex, and the layout space left for the steering system is also more cramped. Therefore, the existing steering system has been updated from the traditional two-stage steering shaft to a three-stage intermediate shaft. The advantage of the three-stage steering shaft is that it can change direction multiple times to adapt to complex spatial environments, and can reduce the torque fluctuation between the input shaft and the output shaft (reaching the requirement of less than 5%).

[0003] However, in order to ensure the stability of the three-section steering shaft after assembly, it has an additional middle section fixing point in its structure compared to the two-section steering shaft, and this fixing point is prone to deviation during assembly. Through three-coordinate measurement, it was found that the Y coordinate of the first stud at the fixing point was too small, and the Y coordinate of the second stud was too large, thus forming a lever at the bracket, and then accumulating the installation margin of the screw hole and the stud, causing the offset of the middle universal joint to be much larger than the estimated value (if the fixing point has a deviation of 1mm, under the effect of the lever principle, it may cause a deviation of more than 10mm in the Y direction of the middle universal joint), and then the three-section steering shaft (especially the middle universal joint and the middle shaft) will interfere with the vehicle body, seriously affecting the steering safety of the vehicle. Summary of the invention

[0004] In view of this, the purpose of this application is to provide a CATIA-based three-section steering shaft calibration method to solve the problem that the existing three-section steering shaft is prone to deviation during assembly, which in turn causes the three-section steering shaft to easily interfere with the vehicle body.

[0005] According to the above purpose, the present invention provides a calibration method for a three-section steering shaft based on CATIA, wherein the calibration method for a three-section steering shaft based on CATIA comprises the following steps:

[0006] S10: building a model of a three-section steering shaft in CATIA software and forming a basic coordinate system, wherein the three-section steering shaft includes a first shaft system, a second universal joint, and a second shaft system connected in sequence;

[0007] S20: revising the coordinates of the bracket assembly in the second axis system so as to be able to simulate the maximum offset state of the bracket assembly in the CATIA software;

[0008] S30: changing the positions of the first axis system and the second axis system through the coordinate transformation function of the CATIA software to simulate the maximum offset state of the three-section steering axis;

[0009] S40: Verifying whether the gap between the three-section steering shaft and the vehicle body after the offset meets the standard;

[0010] S50: When the gap between the three-section steering shaft and the vehicle body meets the standard, production and assembly can be carried out; when the gap between the three-section steering shaft and the vehicle body does not meet the standard, the coordinates of the bracket assembly are readjusted and step S20 is repeated.

[0011] Preferably, the first shaft system comprises a first universal joint, a spline tube and a spline shaft connected in sequence; the spline shaft can be telescopic relative to the spline tube, and the telescopic end of the spline shaft is connected to the second universal joint.

[0012] Preferably, the second shaft system includes the rigid shaft and a third universal joint connected in sequence; and the bracket assembly is sleeved on the outer side of the rigid shaft.

[0013] Preferably, the bracket assembly includes an axle bracket and a body welding bracket which are sleeved on the outer side of the rigid shaft, and the axle bracket and the body welding bracket are both formed with a first screw hole and a second screw hole, the two first screw holes are connected by a first stud, and the two second screw holes are connected by a second stud.

[0014] Preferably, the first screw hole and the second screw hole are distributed along the axial direction of the rigid shaft, and the first screw hole is located above the second screw hole close to the second universal joint.

[0015] Preferably, in S20, the coordinates of the first stud are revised to (X, Yn, Z), and the coordinates of the second stud are revised to (X, Y+n, Z); the coordinates of the first screw hole are revised to (X, Ym, Z), and the coordinates of the second screw hole are revised to (X, Y+m, Z) to obtain the revised position of the bracket assembly.

[0016] Preferably, step S30 specifically includes the following steps:

[0017] S310: Establishing a first coordinate system;

[0018] S320: Establishing a second coordinate system, and transforming the second universal joint and the rigid axis from the first coordinate system to the second coordinate system through the coordinate transformation function of the CATIA software, so as to obtain the offset positions of the second universal joint and the rigid axis.

[0019] Preferably, the center point of the third universal joint is set as the first center point, the center of the bearing of the shaft support at the initial position is set as the first bearing center, the coordinate origin of the first coordinate system is the first center point, and the X-axis of the first coordinate system is the line connecting the first center point and the first bearing center;

[0020] The center of the bearing of the shaft support set at the revised position is the second bearing center, the coordinate origin of the second coordinate system is the first center point, and the X-axis of the second coordinate system is the line connecting the first center point and the second bearing center.

[0021] Preferably, step S30 further includes the following steps:

[0022] S330: Establishing a third coordinate system;

[0023] S340: Establishing a fourth coordinate system, and transforming the spline tube and the spline shaft from the third coordinate system to the fourth coordinate system through the coordinate transformation function of the CATIA software, so as to obtain the offset positions of the spline tube and the spline shaft.

[0024] Preferably, the center point of the first universal joint is set as the second center point, the center point of the second universal joint at the initial position is set as the third center point, the coordinate origin of the third coordinate system is the second center point, and the X-axis of the third coordinate system is the line connecting the second center point and the center of the third bearing;

[0025] The center point of the second universal joint after being offset in step S320 is set as the fourth center point, the coordinate origin of the fourth coordinate system is the second center point, and the X-axis of the fourth coordinate system is the line connecting the second center point and the fourth center point.

[0026] According to a CATIA-based three-section steering shaft verification method of the present invention, in the design stage of the three-section steering shaft, the maximum offset state of the bracket assembly (i.e., the middle section fixed point) can be simulated in the CATIA software; then the coordinate transformation function of the CATIA software is used to simulate the maximum offset state of the three-section steering shaft; and then the software is verified to see whether the gap between the offset three-section steering shaft (especially its second universal joint, i.e., the middle universal joint described in the background technology) and the vehicle body meets the standard. If it meets the assembly requirements, the physical component can be assembled; if it does not meet the assembly requirements, the offset parameters of the bracket assembly in the CATIA software can be readjusted in combination with the dimensional tolerances that can be achieved in production, and the above steps are repeated until the verification is qualified.

[0027] In this way, this verification method can achieve accurate control of the gap between the three-section steering shaft and the body before vehicle assembly, so as to avoid the situation where the interference between the intermediate shaft and the body is found after the engine is assembled, thereby effectively saving manpower and material resources. Furthermore, this verification method can be used to detect whether the size deviation of the welding studs of the body here is within the expected range when the white body is welded to the assembly in the early stage, so as to judge in advance whether the assembly of the whole vehicle can proceed smoothly, thereby ensuring the assembly efficiency and smoothness of the assembly.

[0028] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 is a flow chart of a calibration method for a three-section steering shaft based on CATIA according to the present invention;

[0031] Figure 2 is a schematic diagram of a three-section steering shaft according to the present invention;

[0032] Figure 3 is a schematic diagram of a bracket assembly according to the present invention in a basic coordinate system;

[0033] Figure 4 It is a schematic diagram of the bracket assembly after coordinate revision according to the present invention.

[0034] Icons: 1-first universal joint; 2-spline tube; 3-spline shaft; 4-second universal joint; 5-rigid shaft; 6-shaft bracket; 7-first stud; 8-second stud; 9-body welding bracket; 10-third universal joint; DETAILED DESCRIPTION

[0035] The following specific embodiments are provided to help the reader obtain a comprehensive understanding of the methods, devices and / or systems described herein. However, after understanding the disclosure of the present application, various changes, modifications and equivalents of the methods, devices and / or systems described herein will be apparent. For example, the order of operations described herein is merely an example, and is not limited to the order set forth herein, but in addition to the operations that must occur in a particular order, changes that will be apparent after understanding the disclosure of the present application may be made. In addition, in order to improve clarity and brevity, descriptions of features known in the art may be omitted.

[0036] The features described herein may be implemented in different forms and should not be interpreted as being limited to the examples described herein. Rather, the examples described herein have been provided only to illustrate some of the many possible ways of implementing the methods, devices and / or systems described herein that will be apparent after understanding the disclosure of the present application.

[0037] Throughout the specification, when an element (such as a layer, a region, or a substrate) is described as being “on”, “connected to”, “bound to”, “over”, or “covering” another element, it may be directly “on”, “connected to”, “bound to”, “over”, or “covering” another element, or one or more other elements may be present between them. In contrast, when an element is described as being “directly on”, “directly connected to”, “directly bound to”, “directly over”, or “directly covering” another element, there may be no other elements present between them.

[0038] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0039] Although terms such as "first," "second," and "third" may be used herein to describe various members, components, regions, layers, or portions, these members, components, regions, layers, or portions are not limited by these terms. Rather, these terms are only used to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Therefore, without departing from the teachings of the examples described herein, the first member, component, region, layer, or portion referred to may also be referred to as the second member, component, region, layer, or portion.

[0040] For ease of description, spatial relational terms such as "above", "upper", "below", and "lower" may be used herein to describe the relationship of one element to another element as shown in the accompanying drawings. Such spatial relational terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, an element described as being "above" or "upper" relative to another element will subsequently be "below" or "lower" relative to the other element. Therefore, the term "above" includes both "above" and "below" orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relational terms used herein will be interpreted accordingly.

[0041] The terms used herein are only used to describe various examples and are not used to limit the present disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms "include", "comprise" and "have" list the stated features, quantities, operations, components, elements and / or their combinations that exist, but do not exclude the existence or addition of one or more other features, quantities, operations, components, elements and / or their combinations.

[0042] Variations in the shapes shown in the drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the drawings but include variations in shapes that occur during manufacturing.

[0043] The features of the examples described herein may be combined in various ways that will be apparent after understanding the disclosure of the present application. In addition, although the examples described herein have various configurations, other configurations are possible as will be apparent after understanding the disclosure of the present application.

[0044] The present invention provides a CATIA-based three-section steering shaft verification method, which can realize accurate control of the gap between the three-section steering shaft and the vehicle body before vehicle assembly, and can also judge in advance whether the whole vehicle assembly can proceed smoothly when the white body is welded to the assembly in the early stage. In the following, the verification steps and verification principle of the CATIA-based three-section steering shaft verification method of the present invention will be described in detail.

[0045] The verification method of the three-section steering shaft based on CATIA includes the following steps:

[0046] S10: building a model of a three-section steering shaft in CATIA software and forming a basic coordinate system, wherein the three-section steering shaft includes a first shaft system, a second universal joint, and a second shaft system connected in sequence;

[0047] S20: revising the coordinates of the bracket assembly in the second axis system so as to be able to simulate the maximum offset state of the bracket assembly in the CATIA software;

[0048] S30: changing the positions of the first axis system and the second axis system through the coordinate transformation function of the CATIA software to simulate the maximum offset state of the three-section steering axis;

[0049] S40: Verifying whether the gap between the three-section steering shaft and the vehicle body after the offset meets the standard;

[0050] S50: When the gap between the three-section steering shaft and the vehicle body meets the standard, production and assembly can be carried out; when the gap between the three-section steering shaft and the vehicle body does not meet the standard, the coordinates of the bracket assembly are readjusted and step S20 is repeated.

[0051] Specifically, in step S10, Figure 2 As shown, the first shaft system includes a first universal joint, a spline tube and a spline shaft connected in sequence, the spline shaft can be telescopic relative to the spline tube, and the telescopic end of the spline shaft is connected to the second universal joint. In addition, the second shaft system includes a rigid shaft and a third universal joint connected in sequence, one end of the rigid shaft away from the third universal joint is connected to the second universal joint, and a bracket assembly is sleeved on the outer side of the rigid shaft.

[0052] More specifically, the bracket assembly includes an axle bracket and a body welding bracket that are sleeved on the outer side of the rigid shaft, so that by connecting the axle bracket and the body welding bracket, a stable connection between the three-section steering shaft and the body can be achieved. Furthermore, the axle bracket and the body welding bracket are both formed with a first screw hole and a second screw hole (that is, the axle bracket is formed with a first screw hole and a second screw hole, and the body welding bracket is also formed with a first screw hole and a second screw hole), the two first screw holes are connected by a first stud, and the two second screw holes are connected by a second stud, so as to achieve a stable connection between the axle bracket and the body welding bracket. It should be noted that in order to improve the stability of the connection between the axle bracket and the body welding bracket, the first screw hole and the second screw hole are distributed along the axial direction of the rigid shaft, and the first screw hole is located above the second screw hole close to the second universal joint (such as Figures 2 to 4 shown).

[0053] It should be noted that the above structure is the structure of an existing three-section steering shaft, so the more specific connection and assembly relationship thereof will not be described in detail. In addition, in step S10, in the basic coordinate system that can be automatically formed by the CATIA software, the positive direction of the X axis is the direction toward the rear of the vehicle, the positive direction of the Y axis is the direction toward the right of the vehicle, and the positive direction of the Z axis is the direction toward the top of the vehicle. The directions of the above coordinate axes meet the inherent requirements when modeling the three-section steering shaft.

[0054] The above-mentioned bracket assembly, as the middle fixed point of the three-section steering shaft, is prone to deviation during assembly, which will cause the offset of the second universal joint to be much greater than the estimated value under the action of the lever, and then the three-section steering shaft (especially its second universal joint and rigid shaft) will interfere with the vehicle body, seriously affecting the steering safety of the vehicle. Therefore, in the above-mentioned step S20, the maximum offset state of the bracket assembly is simulated by revising the coordinates of the bracket assembly, and then the three-section steering shaft is calibrated. Specifically, the coordinates of the first stud are revised to (X, Yn, Z), and the coordinates of the second stud are revised to (X, Y+n, Z); the coordinates of the first screw hole are revised to (X, Ym, Z), and the coordinates of the second screw hole are revised to (X, Y+m, Z) to obtain the revised position of the bracket assembly.

[0055] It should be noted that the above "n" and "m" should be determined according to the tolerances of the two studs and the corresponding screw holes. For example, when the X, Y, and Z coordinate tolerances of the studs are (-1mm, +1mm), in order to facilitate assembly, the diameter of the screw hole is 1mm larger than the diameter of the corresponding stud. Therefore, the screw hole (inner diameter) is 0.5mm larger than the stud (outer diameter) on one side. Therefore, in the CATIA model, the coordinates of the first stud are revised to (X, Y-1, Z), and the coordinates of the second stud are revised to (X, Y+1, Z); the coordinates of the first screw hole are revised to (X, Y-1.5, Z), and the coordinates of the second screw hole are revised to (X, Y+1.5, Z) to obtain the revised position of the bracket assembly, which meets the maximum offset of the cumulative tolerance (such as Figure 4 shown).

[0056] It should be further explained that the coordinates of each component in the bracket assembly before revision are (X, Y, Z), and the revised coordinates are relative values ​​to the coordinates before revision. In addition, during the assembly process of the bracket assembly, the nuts on the first stud and the second stud need to be tightened at the end, causing the center of gravity of the entire rigid shaft to shift negatively toward the Y axis, that is, the installation error will shift negatively toward the Y axis, so in step S20, only the Y coordinates of each component in the bracket assembly are revised. In addition, through three-coordinate measurement, it was found that the Y coordinate of the first stud of all problematic vehicles was too small, and the Y coordinate of the second stud was too large, so the bracket assembly was revised as above.

[0057] In the above step 30, it specifically includes the following steps:

[0058] S310: Establishing a first coordinate system;

[0059] S320: establishing a second coordinate system, and transforming the second universal joint and the rigid axis from the first coordinate system to the second coordinate system through the coordinate transformation function of the CATIA software, so as to obtain the offset positions of the second universal joint and the rigid axis;

[0060] S330: Establishing a third coordinate system;

[0061] S340: Establishing a fourth coordinate system, and transforming the spline tube and the spline shaft from the third coordinate system to the fourth coordinate system through the coordinate transformation function of the CATIA software, so as to obtain the offset positions of the spline tube and the spline shaft.

[0062] Through the extreme positions of the second universal joint, rigid shaft, spline tube and spline shaft after offset, the specific gap between each component of the three-section steering shaft and the vehicle body can be known, and it can be verified whether the gap between the three-section steering shaft and the vehicle body meets the assembly process requirements, so as to avoid the situation where the intermediate shaft or other components are found to interfere with the vehicle body after the engine is assembled, thereby effectively saving manpower and material resources. In addition, when the white body is welded to the assembly in the early stage, the three-coordinate measuring machine can be used to detect whether the size deviation of the studs in the bracket assembly is within the expected range, so as to judge in advance whether the assembly of the whole vehicle can proceed smoothly, thereby ensuring the assembly efficiency and smoothness.

[0063] It should be noted that, since the spline shaft and the spline tube can be relatively telescopic, the simultaneous offset of the second universal joint, rigid shaft, spline tube and spline shaft can be achieved. In addition, when verifying whether the gap between the offset three-section steering shaft (especially its second universal joint) and the vehicle body meets the standard, the assembly of the physical components can be carried out; if it is verified that a certain component of the three-section steering shaft does not meet the assembly requirements, the offset parameters of the bracket assembly in the CATIA software can be readjusted in combination with the dimensional tolerances that can be achieved in production, and the above steps are repeated until the verification is qualified. For example, the Y-direction tolerance of the first stud is modified to (0, 1mm), the Y-direction tolerance of the second stud is modified to (-1mm, 0), and the size of the corresponding screw hole is reduced so that the screw hole (inner diameter) is 0.25mm larger than the stud (outer diameter) on one side, and then re-verified and checked.

[0064] In this verification method, the center point of the third universal joint is set as the first center point, the center of the bearing of the shaft support at the initial position is set as the first bearing center, the coordinate origin of the first coordinate system is the first center point, and the X-axis of the first coordinate system is the line connecting the first center point and the first bearing center (the Y-axis and Z-axis of the first coordinate system can be automatically generated using CATIA software after the X-axis is confirmed); the center of the bearing of the shaft support at the revised position is set as the second bearing center, the coordinate origin of the second coordinate system is the first center point, and the X-axis of the second coordinate system is the line connecting the first center point and the second bearing center.

[0065] Similarly, the center point of the first universal joint is set as the second center point, the center point of the second universal joint at the initial position is set as the third center point, the coordinate origin of the third coordinate system is the second center point, and the X-axis of the third coordinate system is the line between the second center point and the center of the third bearing; the center point of the second universal joint after offset in step S320 is set as the fourth center point, the coordinate origin of the fourth coordinate system is the second center point, and the X-axis of the fourth coordinate system is the line between the second center point and the fourth center point.

[0066] It should be noted that the center point of the third universal joint is used to connect the steering gear, and the center point of the first universal joint is used to connect the steering column and the steering wheel, so the positions of the two will never change, that is, the two can form the coordinate origin.

[0067] According to the verification method of the three-section steering shaft based on CATIA as described above, in the design stage of the three-section steering shaft, the maximum offset state of the bracket assembly can be simulated in the CATIA software; then the coordinate transformation function of the CATIA software is used to simulate the maximum offset state of the three-section steering shaft; and then the software is verified to see whether the gap between the offset three-section steering shaft (especially its second universal joint) and the vehicle body meets the standard. If it meets the assembly requirements, the physical component can be assembled; if it does not meet the assembly requirements, the offset parameters of the bracket assembly in the CATIA software can be readjusted in combination with the dimensional tolerances that can be achieved in production, and the above steps are repeated until the verification is qualified.

[0068] In this way, this verification method can achieve accurate control of the gap between the three-section steering shaft and the body before vehicle assembly, so as to avoid the situation where the interference between the intermediate shaft and the body is found after the engine is assembled, thereby effectively saving manpower and material resources. Furthermore, this verification method can be used to detect whether the size deviation of the welding studs of the body here is within the expected range when the white body is welded to the assembly in the early stage, so as to judge in advance whether the assembly of the whole vehicle can proceed smoothly, thereby ensuring the assembly efficiency and smoothness of the assembly.

[0069] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be described in the protection scope of the claims.

Claims

1. A calibration method for a three-section steering shaft based on CATIA, characterized in that: The CATIA-based three-section steering shaft verification method comprises the following steps: S10: building a model of a three-section steering shaft in CATIA software and forming a basic coordinate system, wherein the three-section steering shaft includes a first shaft system, a second universal joint, and a second shaft system connected in sequence; S20: revising the coordinates of the bracket assembly in the second axis system so as to be able to simulate the maximum offset state of the bracket assembly in the CATIA software; S30: changing the positions of the first axis system and the second axis system through the coordinate transformation function of the CATIA software to simulate the maximum offset state of the three-section steering axis; S40: Verifying whether the gap between the three-section steering shaft and the vehicle body after the offset meets the standard; S50: When the gap between the three-section steering shaft and the vehicle body meets the standard, production and assembly can be carried out; when the gap between the three-section steering shaft and the vehicle body does not meet the standard, the coordinates of the bracket assembly are readjusted and step S20 is repeated.

2. The CATIA-based three-section steering shaft calibration method according to claim 1 is characterized in that: The first shaft system includes a first universal joint, a spline tube and a spline shaft connected in sequence; the spline shaft can be telescopic relative to the spline tube, and the telescopic end of the spline shaft is connected to the second universal joint.

3. The CATIA-based three-section steering shaft calibration method according to claim 2 is characterized in that: The second shaft system includes the rigid shaft and the third universal joint connected in sequence; the bracket assembly is sleeved on the outer side of the rigid shaft.

4. The CATIA-based three-section steering shaft calibration method according to claim 3 is characterized in that: The bracket assembly includes an axle bracket and a body welding bracket sleeved on the outer side of the rigid shaft, the axle bracket and the body welding bracket are both formed with a first screw hole and a second screw hole, the two first screw holes are connected by a first stud, and the two second screw holes are connected by a second stud.

5. The CATIA-based three-section steering shaft calibration method according to claim 4 is characterized in that: The first screw hole and the second screw hole are distributed along the axial direction of the rigid shaft, and the first screw hole is located above the second screw hole close to the second universal joint.

6. The CATIA-based three-section steering shaft calibration method according to claim 5, characterized in that: In S20, the coordinates of the first stud are revised to (X, Yn, Z), and the coordinates of the second stud are revised to (X, Y+n, Z); the coordinates of the first screw hole are revised to (X, Ym, Z), and the coordinates of the second screw hole are revised to (X, Y+m, Z) to obtain the revised position of the bracket assembly.

7. The CATIA-based three-section steering shaft calibration method according to claim 5, characterized in that: Step S30 specifically includes the following steps: S310: Establishing a first coordinate system; S320: Establishing a second coordinate system, and transforming the second universal joint and the rigid axis from the first coordinate system to the second coordinate system through the coordinate transformation function of the CATIA software, so as to obtain the offset positions of the second universal joint and the rigid axis.

8. The CATIA-based three-section steering shaft calibration method according to claim 7, characterized in that: The center point of the third universal joint is set as the first center point, the center of the bearing of the shaft support at the initial position is set as the first bearing center, the origin of the first coordinate system is set as the first center point, and the X-axis of the first coordinate system is set as the line connecting the first center point and the first bearing center; The center of the bearing of the shaft support set at the revised position is the second bearing center, the coordinate origin of the second coordinate system is the first center point, and the X-axis of the second coordinate system is the line connecting the first center point and the second bearing center.

9. The CATIA-based three-section steering shaft calibration method according to claim 7, characterized in that: Step S30 also includes the following steps: S330: Establishing a third coordinate system; S340: Establishing a fourth coordinate system, and transforming the spline tube and the spline shaft from the third coordinate system to the fourth coordinate system through the coordinate transformation function of the CATIA software, so as to obtain the offset positions of the spline tube and the spline shaft.

10. The CATIA-based three-section steering shaft calibration method according to claim 9, characterized in that: The center point of the first universal joint is set as the second center point, the center point of the second universal joint at the initial position is set as the third center point, the origin of the third coordinate system is the second center point, and the X-axis of the third coordinate system is the line connecting the second center point and the center of the third bearing; The center point of the second universal joint after being offset in step S320 is set as the fourth center point, the coordinate origin of the fourth coordinate system is the second center point, and the X-axis of the fourth coordinate system is the line connecting the second center point and the fourth center point.

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