An adjustable positioning method based on a load-bearing body structure and a subframe

Abstract

The present application belongs to the field of automobile manufacturing, and particularly relates to an adjustable positioning method based on combined mounting of a bearing type vehicle body structure and a subframe. The present application increases an adjustable positioning pin mechanism in a front point area of the subframe, and places the subframe in two sets of positioning fixtures with fixed relative positions, namely a subframe positioning fixture and a vehicle body positioning fixture. The adjustable positioning pin is pre-adjusted and fastened relative to a welding positioning reference of the subframe and a main positioning reference of the vehicle body, and the relative position of the positioning pin is iterated. The pre-adjusted subframe with the adjustable positioning pin is placed in a flexible production line, and the assembly positioning is realized through matching of the adjustable positioning pin and the vehicle body longitudinal beam. The iterated adjustable positioning pin is positioned in the front point area of the subframe, the height relative to a common positioning pin is reduced, and the longitudinal distance from the main positioning reference of the vehicle body is shortened, so that the assembly positioning precision caused by the positioning pin and the workpiece position tolerance is reduced, the influence of the positioning precision caused by springback deformation of the welding positioning pin and the vehicle body welding joint is avoided, and the space occupation risk of the positioning pin to the vehicle body holder is reduced.

Description

Technical Field

[0001] This invention belongs to the field of automobile manufacturing, and specifically relates to an adjustable positioning method based on the assembly of a load-bearing body structure and a subframe. Background Technology

[0002] In monocoque applications, the subframe not only bears the force and displacement from the load and assembles the powertrain, but also improves the lateral symmetry of the vehicle's positioning parameters during the assembly process with the body, providing strong protection for the vehicle's driving stability and safety.

[0003] In flexible assembly processes, two common positioning methods are typically used to improve the accuracy of subframe and body assembly. The first uses AGV positioning fixtures (integrated with support and positioning), and the second uses subframe-mounted positioning pins. In current production practice, AGV positioning fixtures often encounter issues due to excessively high positioning pins, leading to deviations in verticality and exceeding design requirements, thus affecting positioning accuracy. Furthermore, the compatibility of multiple vehicle models on a single platform results in an excessive variety of positioning pins, causing insufficient operating space. The second method, in practice, suffers from springback deformation after welding, resulting in low verticality and positional accuracy of the positioning pins. This can even lead to positioning failures and occupy space for other fixtures, impacting production cycle time. Summary of the Invention

[0004] This invention addresses the issue of platform compatibility across multiple vehicle models, optimizes assembly operation space, and improves precise positioning during assembly. It adds a set of bolted, slightly adjustable locating pins at the front mounting point of the subframe. By matching the subframe with two sets of aligning locating fixtures, the adjustable locating pins fixed to the subframe are aligned with the welding reference holes on the subframe and the main locating holes on the vehicle body.

[0005] This invention adds an adjustable locating pin mechanism to the front area of ​​the subframe, placing the subframe within two sets of relatively fixed locating fixtures: a subframe locating fixture and a body locating fixture. The adjustable locating pin is pre-adjusted and tightened relative to the subframe welding datum and the body main locating datum, achieving iterative positioning of the locating pin. The pre-adjusted subframe with adjustable locating pins is placed in a flexible production line, and assembly positioning is achieved by matching the adjustable locating pins with the body longitudinal beams. The iteratively positioned adjustable locating pin is located in the front area of ​​the subframe, reducing its height relative to conventional locating pins and shortening its longitudinal distance from the body main locating datum. This reduces assembly positioning accuracy issues caused by locating pin and workpiece position tolerances, avoids the impact of springback deformation of welding locating pins and body welded components on positioning accuracy, and minimizes the space occupation risk of the locating pin on the body clamp. The specific technical solution is as follows: An adjustable positioning method based on the assembly of a load-bearing vehicle body structure and a subframe is disclosed. This method employs an adjustable positioning pin, with one end being a tapered shape with a guiding function, and the other end being a screw that engages with a standard nut. The screw diameter is 7mm smaller than the positioning pin body, and the subframe through-hole diameter is 3-4mm larger than the positioning pin screw. The adjustable positioning method includes the following steps: Step (1) Adjust the adjustable positioning pin for pre-adjustment With the relative positions of the subframe positioning fixture and the body positioning fixture remaining unchanged, the subframe assembly is placed on the subframe positioning platform by means of front and rear support blocks. The welding reference holes of the left and right longitudinal beams of the subframe are fixed to the subframe positioning platform by means of the left and right positioning pins. After the body positioning fixture is rotated at a certain angle, it is placed horizontally in the front point area of ​​the subframe. The adjustable positioning pin nuts fastened in the subframe through holes are loosened, so that the adjustable positioning pins can be slightly adjusted in the plane range in the subframe through holes. The adjustable positioning pins located in the left and right front point areas of the subframe are simultaneously inserted into the corresponding left and right positioning holes of the body positioning fixture. After calibration and confirmation, the adjustable positioning pins are re-fastened in the subframe through holes. Step (2) The subframe of the flexible production line is assembled and positioned with the longitudinal beams of the vehicle body; the subframe with the pre-adjusted positioning pins is placed in the AGV platform, and the subframe is connected to the left and right longitudinal beams of the vehicle body by means of the lifting function of the AGV. By means of the guiding effect of the adjustable positioning pins, they are inserted into the left and right positioning holes of the longitudinal beams of the vehicle body, so that the subframe and the vehicle body are assembled and positioned; the bolts connecting the subframe and the vehicle body are tightened in sequence and the torque is confirmed. The AGV tooling is removed to complete the assembly operation of the subframe and the vehicle body.

[0006] Furthermore, in step (1), the subframe is first placed on the subframe positioning platform and then engaged with the welding reference holes of the left and right longitudinal beams of the subframe through the positioning pin. Next, the flip-up body positioning fixture is placed horizontally and placed on the front point through hole of the subframe. By loosening the fastening nut of the adjustable positioning pin, the adjustable positioning pin passes through both the subframe through hole and the fixture positioning hole. At this time, the fastening nut of the adjustable positioning pin is tightened again to the specified torque to ensure that the adjustable positioning pin remains unchanged relative to the welding main positioning reference of the subframe during transportation and assembly.

[0007] Furthermore, in step (1), the relative positions of the vehicle body positioning fixture and the subframe positioning fixture must remain unchanged during the use of the adjustable positioning pin.

[0008] Furthermore, in step (1), the vehicle body positioning fixture is flipped by an angle α, and the positioning of the subframe positioning fixture with the subframe is completed and the adjustable positioning pin is calibrated. The contact and disengagement between the vehicle body positioning fixture and the adjustable positioning pin of the subframe are achieved by flipping the vehicle body positioning fixture.

[0009] Furthermore, in step (2), the left and right adjustable positioning pins corresponding to the subframe are matched with the left and right longitudinal beams of the vehicle body, and the left side of the longitudinal beam is the main positioning hole to constrain the X, Y and Z directions; the right side is the auxiliary positioning direction to constrain the X and Z directions.

[0010] This invention's adjustable positioning pin, based on a tooling pre-adjustment process, iterates the initial position of the positioning pin, changing the original AGV platform positioning to a subframe-integrated positioning pin method. This solves the limitation of tooling universality caused by platform collinearity and avoids the problem of inaccurate end-position of the AGV positioning pin due to height. The automatic positioning method of the subframe is changed from welding at the rear mounting point area to screwing at the front mounting point area, shortening the longitudinal distance between the vehicle body positioning hole and the main reference, improving the accuracy of the vehicle body positioning hole, avoiding deformation after positioning pin welding, and solving the limitation of vehicle body clamp space requirements for rear mounting point positioning. The integrated design of the adjustable positioning pin and subframe further simplifies the functional dependence on the AGV platform, simplifies the arrangement of the positioning pin, and improves the compatibility of the AGV platform. Attached Figure Description

[0011] Figure 1 Adjustable positioning pin pre-adjustment diagram; Figure 2 Schematic diagram of the assembly and positioning of the subframe and body longitudinal beams on a flexible production line; Figure 3 Partial schematic diagram of the adjustable positioning pin matching the subframe.

[0012] Figure label: 1-Vehicle positioning fixture; 2-Adjustable positioning pin; 2.1-End of adjustable positioning pin; 2.2-Standard nut; 3-Subframe assembly; 3.1-Fasting bolt; 3.2-Fasting bolt; 3.3-Welding reference hole; 3.4-Subframe through hole; 4-Subframe positioning fixture; 4.1-Left and right positioning pins; 4.2-Front support block; 4.3-Rear support block; 5-Longitudinal beam assembly; 5.1-Longitudinal beam; 5.2-Positioning hole; 6-AGV fixture. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] like Figure 1-3As shown, the adjustable positioning method based on the assembly of the load-bearing body structure and subframe employs an adjustable positioning pin 2. The end 2.1 of the adjustable positioning pin is a tapered shape with a guiding function, and the other end is a screw that mates with a standard nut 2.2. The screw diameter is 7mm smaller than the positioning pin body, and the diameter of the subframe through hole 3.4 is 3-4mm larger than the positioning pin screw. The 50mm radius area of ​​the subframe through hole 3.4 requires a high degree of flatness. The specific adjustable positioning method is as follows: Step (1): Adjustable positioning pin pre-adjustment. Based on the unchanged relative positions of the subframe positioning fixture 4 and the body positioning fixture 1, the subframe assembly 3 is placed on the subframe positioning fixture 4 using front and rear support blocks 4.2 and 4.3. The welding reference holes 3.3 of the left and right longitudinal beams of the subframe are fixed to the subframe positioning fixture 4 using the corresponding left and right positioning pins 4.1. The body positioning fixture 1 is rotated at a certain angle and placed horizontally in the subframe through-hole 3.4 area. The nuts of the adjustable positioning pins 2, which are fastened in the subframe through-hole 3.4, are loosened, allowing the adjustable positioning pins 2 to be slightly adjusted within the subframe through-hole 3.4. The adjustable positioning pins 2, located in the left and right front point areas of the subframe, are simultaneously inserted into the corresponding left and right positioning holes 1.2 of the body positioning fixture 1. After calibration and confirmation, the adjustable positioning pins 2 are re-fastened into the subframe through-hole 3.4. This completes the adjustable positioning pin pre-adjustment operation.

[0015] Step (2): The subframe of the flexible production line is assembled and positioned with the longitudinal beams of the vehicle body. The subframe 3 with the pre-adjusted positioning pins is placed in the AGV platform 6. With the help of the AGV lifting function, the subframe 3 is connected to the left and right longitudinal beams 5 of the vehicle body. With the guidance of the adjustable positioning pins 2.1, they are inserted into the left and right positioning holes 5.2 of the longitudinal beams of the vehicle body, so that the subframe 3 and the vehicle body are assembled and positioned. The bolts 3.1 and 3.2 connecting the subframe and the vehicle body are tightened in sequence and the torque is confirmed. The AGV tooling 6 is removed to complete the assembly operation of the subframe 3 and the vehicle body.

[0016] In step (1), the subframe 3 is first placed on the subframe positioning fixture 4 and mates with the welding reference holes 3.3 of the left and right longitudinal beams of the subframe through the positioning pin 4.1. Then, the flip-up body positioning fixture 1 is placed horizontally and placed on the subframe through hole 3.4. By loosening the fastening nut of the adjustable positioning pin 2, the adjustable positioning pin 2 passes through both the subframe through hole 3.4 and the fixture positioning hole 1.2. At this time, the fastening nut of the adjustable positioning pin 2 is tightened again to the specified torque to ensure that the adjustable positioning pin 2 remains unchanged relative to the welding main positioning reference 3.3 of the subframe during transportation and assembly. The relative position of the body positioning fixture 1 and the subframe positioning fixture 4 must remain unchanged during the use of the adjustable positioning pin. The body positioning fixture 1 is flipped by an angle α. The subframe 3 completes the positioning with the subframe positioning fixture 4 and the calibration of the adjustable positioning pin 2 is completed. The contact and disengagement between the body positioning fixture 1 and the subframe adjustable positioning pin 2 are achieved by flipping the body positioning fixture 1.

[0017] In step (2), the left and right adjustable positioning pins 2 corresponding to the subframe 3 are matched with the positioning holes 5.2 of the left and right longitudinal beams of the vehicle body, and the left side of the longitudinal beam is the main positioning hole (constraining X, Y, Z), and the right side is the auxiliary positioning direction (constraining X, Z).

[0018] The preferred embodiments of this patent have been described in detail above. However, this patent is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this patent.

Claims

1. An adjustable positioning method based on the combined assembly of a load-bearing vehicle body structure and a subframe, characterized in that: An adjustable positioning pin is used. The end of the pin is tapered with a guiding function, and the other end is a screw that mates with a standard nut. The screw diameter is 7mm smaller than the positioning pin body, and the subframe through-hole diameter is 3-4mm larger than the positioning pin screw. The adjustable positioning method includes the following steps: Step (1) Adjustable positioning pin pre-adjustment: Based on the fact that the relative positions of the subframe positioning fixture and the body positioning fixture remain unchanged, the subframe assembly is placed on the subframe positioning platform by the support of the front and rear support blocks; the welding reference holes of the left and right longitudinal beams of the subframe are fixed to the subframe positioning platform by the left and right positioning pins of the subframe positioning platform. After flipping the vehicle body positioning fixture at a certain angle, place it horizontally in the front point area of ​​the subframe. Loosen the adjustable positioning pin nut that is fastened in the through hole of the subframe, so that the adjustable positioning pin can be slightly adjusted in the plane range within the through hole of the subframe. Simultaneously pass the adjustable positioning pin located in the left and right front point areas of the subframe through the corresponding left and right positioning holes of the vehicle body positioning fixture. After completing the calibration and confirmation, re-fasten the adjustable positioning pin in the through hole of the subframe. Step (2) The subframe of the flexible production line is assembled and positioned with the longitudinal beams of the vehicle body; the subframe with the pre-adjusted positioning pins is placed in the AGV platform, and the subframe is connected to the left and right longitudinal beams of the vehicle body by means of the lifting function of the AGV. By means of the guiding effect of the adjustable positioning pins, they are inserted into the left and right positioning holes of the longitudinal beams of the vehicle body, so that the subframe and the vehicle body are assembled and positioned; the bolts connecting the subframe and the vehicle body are tightened in sequence and the torque is confirmed. The AGV tooling is removed to complete the assembly operation of the subframe and the vehicle body.

2. The adjustable positioning method based on the assembly of a load-bearing vehicle body structure and a subframe according to claim 1, characterized in that: In step (1), the subframe is first placed on the subframe positioning platform and then engaged with the welding reference holes of the left and right longitudinal beams of the subframe through the positioning pin. Next, the flip-up body positioning fixture is placed horizontally and placed on the front point through hole of the subframe. By loosening the fastening nut of the adjustable positioning pin, the adjustable positioning pin passes through both the subframe through hole and the fixture positioning hole. At this time, the fastening nut of the adjustable positioning pin is tightened again to the specified torque to ensure that the adjustable positioning pin remains unchanged relative to the welding main positioning reference of the subframe during transportation and assembly.

3. The adjustable positioning method based on the assembly of a load-bearing vehicle body structure and a subframe according to claim 1, characterized in that: In step (1), the relative positions of the vehicle body positioning fixture and the subframe positioning fixture must remain unchanged during the use of the adjustable positioning pin.

4. The adjustable positioning method based on the assembly of a load-bearing vehicle body structure and a subframe according to claim 1, characterized in that: In step (1), the vehicle body positioning fixture is rotated by an angle α, and the positioning of the sub-frame positioning fixture with the sub-frame is completed and the adjustable positioning pin is calibrated. The vehicle body positioning fixture is rotated to achieve contact and disengagement with the adjustable positioning pin of the sub-frame.

5. The adjustable positioning method based on the assembly of a load-bearing vehicle body structure and a subframe according to claim 1, characterized in that: In step (2), the left and right adjustable positioning pins corresponding to the subframe are matched with the left and right longitudinal beams of the vehicle body, and the left side of the longitudinal beam is the main positioning hole to constrain the X, Y and Z directions; the right side is the auxiliary positioning direction to constrain the X and Z directions.

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