A combined method for reducing the deformation of a body-in-white for moonroof testing

Abstract

The application relates to a combined method for reducing the deformation of a body-in-white for a sunroof test. The method uses a trial product with low precision to manufacture a body-in-white assembly with high precision at the sunroof position by increasing internal constraints in the whole process and adopting intermittent brazing. The method has the advantages that the precision requirement of part matching size is relatively low, the part delivery cycle is shortened, the vehicle development speed is improved, and the precision of the body-in-white assembly at the sunroof position is improved. The overall process of the method comprises six steps: part fixing in a clamp, increasing internal constraints, intermittent brazing, opening the clamp, painting and removing the internal constraints.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of body-in-white trial, in particular to a combined method for reducing deformation of body-in-white for sunroof test. BACKGROUND

[0002] The automobile market competition is increasingly fierce, and the vehicle development cycle is getting shorter and shorter. Sunroof test is one of the indispensable tests. In order to trial a qualified body-in-white for sunroof test as soon as possible, it is necessary to trial a high-precision body-in-white assembly with a low-precision early trial mold.

[0003] The existing body-in-white for sunroof test adopts the same production process and technology as other body-in-white for test, that is, the roof assembly is continuously laser brazed under the constraint of external clamps, and after completion, the external clamps are removed for subsequent processing. This method requires high precision of parts, and the precision of the sunroof part of the body-in-white assembly is difficult to guarantee due to internal stress.

[0004] In view of the above problems, the method disclosed in Chinese invention patent CN109175750A "Method for reducing welding deformation of vehicle body" is as follows: first, fix the heat dissipation member on the clamp, and press the heat dissipation member tightly on the surface of the workpiece to be welded by the clamp, the heat dissipation member is arranged along the welding seam direction of the workpiece to be welded, and the distance between the heat dissipation member and the welding seam of the workpiece to be welded is set, then the workpiece to be welded is welded.

[0005] The above-mentioned invention reduces the welding deformation of the vehicle body by adding a heat dissipation device. Because the heat dissipation device needs to be added along the welding seam direction and needs to be attached to the surface of the part, a large number of parts that need to be numerically controlled are added, which increases the cost; at the same time, in order to arrange the heat dissipation device, the operation space is also reduced. SUMMARY

[0006] In view of the above problems, the present application provides a combined method for reducing deformation of body-in-white for sunroof test.

[0007] The combined method reduces the deformation of the body-in-white during trial and reduces the precision requirement of the trial part by increasing internal constraint throughout the process and adopting intermittent brazing welding method when processing the body-in-white for sunroof test. The method comprises: increasing internal constraint throughout the process, and removing the internal constraint after coating is completed; and using other welding process to replace the part that does not meet the brazing matching requirement.

[0008] Further, the steps of the combined method comprise:

[0009] S1. Fix the part on the clamp:

[0010] In the matching process of the roof outer plate and the body-in-white skeleton assembly, the roof outer plate is fixed on the clamp according to the preset positioning system, and is pressed tightly in sequence.

[0011] S2. Increase internal constraints:

[0012] Three groups of diagonal beams are fixed inside the vehicle body to apply constraints to the body-in-white to reduce deformation and are evenly distributed along the length of the roof.

[0013] S3. Intermittent brazing:

[0014] From the front to the rear of the vehicle, intermittent brazing is used, i.e. brazing and other welding methods are alternately used.

[0015] S4. Open the clamp:

[0016] The clamp is opened and the body-in-white assembly is removed with a skid.

[0017] S5. Painting:

[0018] The body-in-white assembly is subjected to subsequent processing, including door cover assembly, phosphating and electrophoresis, until the entire painting process is completed.

[0019] S6. Remove internal constraints:

[0020] After the painting process is completed, it is transported to the test site and the internal constraints are removed with mechanical tools to obtain a body-in-white for sunroof testing.

[0021] Further, in step S1, the roof outer panel is a trial piece used for the body-in-white assembly for trial sunroof testing, and the precision of the trial piece is selected as needed.

[0022] Further, in step S2, the distance between the diagonal beams is 300-500 mm.

[0023] Further, in step S2, two diagonal beams are provided in each group; one end of one of the diagonal beams is fixed to the upper part of the left side wall inner panel in the contact area with the roof, and the other end is fixed to the right floor near the rocker area; the other end of the other diagonal beam is fixed to the upper part of the right side wall inner panel in the contact area with the roof, and the other end is fixed to the left floor near the rocker area.

[0024] Further, the plane formed by the two diagonal beams is parallel to the YZ plane of the vehicle body.

[0025] Further, in step S2, the contact part between the diagonal beam and the roof outer panel is connected by carbon dioxide shielded welding.

[0026] Further, in step S3, when intermittent brazing is used, the normal distance between the side wall outer panel and the roof outer panel is not greater than 0.3 mm and the gap is uniform, and the remaining parts are welded by using soldering and CMT welding.

[0027] Furthermore, in step S3, the total length of the brazed weld reaches more than 60% of the design length. The design length is the weld length marked by the designer of the sunroof test vehicle body on three-dimensional data or two-dimensional drawings.

[0028] The beneficial effects of the present invention are as follows: By increasing internal constraints throughout the process and adopting intermittent brazing, the present invention reduces the precision requirements of the prototype parts, and a high-precision body-in-white assembly for the sunroof part can be produced using a prototype mold with lower precision.

[0029] The reason why this invention can reduce the precision requirements of the prototype is that: by adopting the method of internal constraint throughout the process, the deformation of the body-in-white assembly during the prototype manufacturing process is effectively reduced. This ensures that each adjustment of the body assembly to fit with the roof outer panel is an effective adjustment. Because of the improved adjustment efficiency, the precision requirements of the initial roof outer panel prototype are reduced, and the precision of the sunroof part of the body-in-white assembly is also improved. The use of intermittent brazing improves welding efficiency, shortens the parts production cycle, and increases the vehicle development speed. Attached Figure Description

[0030] Figure 1 This is a flowchart of the combination method of the present invention;

[0031] Figure 2 This is a constraint diagram for a single set of inclined beams;

[0032] Figure 3 This is a cross-sectional view of a single set of inclined beams under constraint.

[0033] Figure 4 This is a detailed view of point B;

[0034] Figure 5 This is a detailed view of point C. Detailed Implementation

[0035] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. 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.

[0036] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for 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. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] The existing sunroof test body-in-white uses the same production process and technology as other test body-in-whites, namely, continuous laser brazing of the roof assembly under external fixture constraints, followed by removal of the external fixtures for subsequent processing. This method requires high precision of the parts, and the precision of the sunroof section of the body-in-white assembly is difficult to guarantee due to internal stress.

[0039] This invention, by increasing internal constraints throughout the entire process and employing intermittent brazing, produced a high-precision body-in-white assembly for the sunroof area using prototypes with lower precision. It has relatively low requirements for the dimensional accuracy of part matching; shortens the part production cycle and increases vehicle development speed; and improves the precision of the sunroof area in the body-in-white assembly.

[0040] like Figure 1 The diagram shows the overall flow of the method described in this invention, which consists of six steps: fixing the part in the fixture, adding internal constraints, intermittent brazing, opening the fixture, painting, and removing internal constraints.

[0041] Each step will be explained in detail below with reference to the accompanying diagrams.

[0042] Parts are fixed in the fixture: In the process of matching the outer panel of the roof cover with the body-in-white frame assembly, the outer panel of the roof cover is fixed on the fixture according to the preset positioning system, and pressed in sequence to ensure reliability and stability. The outer panel of the roof cover is a prototype part used in the trial production of the body-in-white assembly for the sunroof test. The precision of the prototype part is selected as needed. A high-precision T0 part or a low-precision prototype part can be selected.

[0043] Increase internal constraints: Three sets of inclined beams are fixed inside the vehicle body to constrain the outer panel of the roof and reduce deformation. These beams are evenly distributed along the length of the roof, with a spacing of approximately 300mm-500mm between each set. Figure 2 The diagram shows one type of inclined beam, consisting of two beams in each group. One beam has one end fixed to the area above the inner panel of the left side assembly where it contacts the roof, and the other end fixed to the area near the sill on the right floor. The other beam has one end fixed to the area above the inner panel of the right side assembly where it contacts the roof, and the other end fixed to the area near the sill on the left floor. The plane formed by the two beams must be parallel to the YZ plane of the vehicle body.

[0044] like Figure 3 The diagram shown is a cross-sectional view of a single set of inclined beams. The inclined beams are connected to the body-in-white using CO2 shielded welding. A detailed view of area B after the connection is shown below. Figure 4 As shown; the area where the inclined beam contacts the vehicle floor is CNC machined according to the specific shape of the vehicle floor sheet metal part. A detailed view of the connection area C between the machined inclined beam and the vehicle floor sheet metal part is shown below. Figure 5 As shown in the figure, the inclined beam at the location has been processed to match the shape of the body floor sheet metal parts.

[0045] Intermittent brazing: Brazing requires a high degree of part matching, with the normal distance between the side panel and the roof panel not exceeding 0.3mm and the gap being uniform. Therefore, perfect matching cannot be achieved before quality control. Based on the degree of matching, this invention employs intermittent brazing from the front to the rear of the vehicle to reduce the precision requirements on the parts. Brazing is performed on areas meeting the brazing conditions, while other welding methods are used on areas that do not meet the conditions. Simultaneously, the total weld length is guaranteed to reach at least 60% of the design length, with the remaining areas replaced by soldering or other welding methods.

[0046] Open the clamps: Open the clamps and remove the body-in-white assembly with a skid. At this time, the internal springback of the body-in-white is constrained by the inclined beam, which reduces the springback deformation of the body caused by stress release.

[0047] Painting: Subsequent processing of the body-in-white assembly, such as door and hood assembly, phosphating, electrophoresis, until all painting processes are completed.

[0048] Remove internal constraints:

[0049] After the painting process is completed, the vehicle is transported to the test site, where the internal constraints are removed using mechanical tools to obtain a stable white body.

Claims

1. A method for reducing deformation of a white body used in sunroof testing, characterized in that, The steps of the method include: S1. The part is fixed in the fixture: In the process of matching the outer roof panel with the body-in-white frame assembly, the outer roof panel is fixed on the fixture according to the preset positioning system and pressed in sequence; S2. Add internal constraints: Three sets of inclined beams are fixed inside the vehicle body to constrain the body-in-white and reduce deformation, and are evenly distributed along the length of the roof. S3. Intermittent brazing: Welding is performed from the front to the rear of the vehicle using an intermittent brazing method. S4. Open the clamp: The clamps are opened, and the body-in-white assembly is removed using a skid; S5. Painting: Subsequent processing of the body-in-white assembly, including door and hood assembly, phosphating and electrophoresis, until all painting processes are completed; S6. Remove internal constraints: After the painting process is completed, the vehicle is transported to the test site, where the internal constraints are removed using mechanical tools to obtain the body-in-white for sunroof testing.

2. The method according to claim 1, characterized in that, In step S1, the outer panel of the top cover is a prototype used in the trial production of the white body assembly for the sunroof test, and the precision of the prototype is selected as needed.

3. The method according to claim 2, characterized in that, In step S2, the spacing between each set of inclined beams is 300-500mm.

4. The method according to claim 3, characterized in that, In step S2, each group is equipped with two inclined beams; one beam is fixed at one end to the area above the inner panel of the left side assembly and in contact with the top cover, and the other end is fixed to the area near the threshold of the right floor; the other beam is fixed at one end to the area above the inner panel of the right side assembly and in contact with the top cover, and the other end is fixed to the area near the threshold of the left floor.

5. The method according to claim 4, characterized in that, The plane formed by the two inclined beams is parallel to the YZ plane of the vehicle body.

6. The method according to claim 5, characterized in that, In step S2, the contact area between the inclined beam and the outer plate of the top cover is connected by carbon dioxide shielded welding.

7. The method according to claim 6, characterized in that, In step S3, during intermittent brazing, brazing is used for parts where the normal distance between the side panel and the top panel is no more than 0.3 mm and the gap is uniform. For the remaining parts, the welding methods include soldering and CMT welding.

8. The method according to claim 7, characterized in that, In step S3, the total length of the brazed weld reaches more than 60% of the design length.

9. The method according to claim 8, characterized in that, The design length is the weld length marked by the designer of the white body for the sunroof test on three-dimensional data or two-dimensional drawings.

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