A method for testing the deformation of the front and rear hood of an automobile by electrophoresis

Abstract

The invention relates to a method for testing the deformation of a hood before and after electrophoresis of an automobile; deformation test points of a hood sheet metal are distributed on the front edge of the hood, combining equal spacing with unequal spacing, and combining symmetry with dispersion; taking the Y-axis symmetry plane of the whole vehicle as the center, at least two pairs of symmetrical measuring points are arranged on the front edge of the hood, and at least two dispersed or asymmetric measuring points are arranged on each side; the deformation measurement of each measuring point adopts a two-time direct measurement method; a deformation measuring tool is installed on the upper half of a hood support fixture, and a caliper or a feeler gauge is used to directly measure the gap between the deformation measuring point on the edge of the hood and the measuring tool before electrophoresis, the deformation measuring tool is removed during electrophoresis, and the deformation measuring tool is installed again in situ after electrophoresis, and the gap between the deformation test point and the deformation measuring tool is measured again, and the difference between the two gaps is the deformation of the hood before and after electrophoresis; the invention has high measurement accuracy, and the measuring device is convenient and detachable, which is conducive to on-site painting operation, does not affect painting production, and has strong work convenience.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile testing, and relates to a method for testing the deformation of a front and rear engine hood of an automobile by electrophoresis. Background Art

[0002] Before and after electrophoretic coating of the automobile body in white, the hood structure is deformed by the complex external force of the electrophoretic liquid impact, which will cause quality problems in the final assembly process. Therefore, it is necessary to obtain the overall and local deformation of the hood before and after electrophoresis, analyze the causes of the deformation, increase the rigidity of the structure during structural design, control or reduce the deformation, and improve / enhance the quality of the final assembly process.

[0003] The engine hood is always in motion when the body-in-white passes through the electrophoretic liquid, and is immersed in the electrophoretic liquid, so only the contact deformation measurement method can be used. If the traditional sensor method is used to measure deformation, only a limited number of sensors can be deployed to test the deformation of a limited number of positions. Because the deformation is small and the electrophoretic liquid will impact the sensor, the test accuracy will decrease. At the same time, the test environment has very high requirements on the sealing and corrosion resistance of the sensor. The long-term deployment of test instruments at the electrophoretic production site will also affect production. Therefore, the method of using sensors to measure the deformation of the engine hood is relatively ineffective and difficult to implement.

[0004] In addition to the experimental test scheme, CAE analysis can also be used to obtain the overall and local deformation values ​​of the engine hood. CAE analysis can obtain deformation cloud maps and calculate the deformation values ​​of any point, but for fluid analysis, it involves fluid-solid coupling technical difficulties, and the current CAE analysis accuracy is not enough to support quantitative analysis. In order to solve the problem of insufficient CAE analysis accuracy and achieve the purpose of using CAE analysis to obtain the deformation of the engine hood during the electrophoresis process, it is necessary to obtain accurate data for verifying the CAE analysis model, design a set of engine hood deformation test methods, obtain the local deformation of the engine hood, and use the local deformation data to verify the CAE analysis model, improve the CAE analysis accuracy, and meet the needs of comprehensively obtaining the overall and local deformation data of the engine hood before and after electrophoresis.

[0005] Before and after electrophoretic coating of the automobile body in white, the sheet metal structure of the engine hood will be deformed due to the complex external force of the electrophoretic liquid impact. The deformation will affect the vehicle appearance and subsequent assembly process. Therefore, it is necessary to obtain the overall and local deformation of the engine hood before and after electrophoresis, analyze the causes of the deformation, improve the structural stiffness during structural design, control or reduce the deformation, and improve the vehicle appearance.

[0006] During electrophoresis, if the hood is kept closed, the paint surface of the hood inner panel will be uneven. To ensure uniform electrophoretic paint coating, the hood needs to be opened at a certain angle. There is a set of tools that use the process holes of the hood and the process holes of the body longitudinal beam to support the hood so that the hood and the body maintain a certain opening angle. To ensure easy loading and unloading, the upper part of this set of tools is tightly connected to the middle part of the hood, and the lower part is connected to the body by a jack connection method, and there is a certain amount of shaking relative to the body and the hood.

[0007] During electrophoresis, the hood is always in motion with the body-in-white, and the hood and body also move relatively. How to obtain the relative deformation of the hood before and after electrophoresis? The conventional solution is to use sensors for actual measurement. If the hood deformation is measured with a sensor, the deformation is small (0.1mm level), there are many relative movement factors, and the sensor needs to be electrophoresed together with the body. The electrophoresis fluid will impact the sensor, resulting in insufficient test accuracy or even measurement failure. At the same time, the sensor has high requirements for waterproofness, high costs for sensors and data acquisition, and high test investment costs, so the solution of using sensors to measure the deformation of the hood is relatively ineffective.

[0008] Patent document 1 (CN207130352U) The utility model discloses a pre-treatment electrophoresis limiter for an automobile engine hood, comprising a telescopic spring, one end of which is connected to a first front anti-collision beam connecting chain, the other end of which is connected to a second front anti-collision beam connecting chain, the other end of which is connected to a first clamping device, the other end of which is connected to a second clamping device, and the two ends of the telescopic spring are also connected to a limiter. The telescopic spring of the utility model is provided with front anti-collision beam connecting chains at both ends, and the telescopic spring can maintain a free length when wound on the front anti-collision beam without electrophoresis, and the telescopic spring is limited by the limiter when electrophoresis starts, the maximum elongation is limited, and the service life is long; the automobile engine hood can be limited on the automobile front anti-collision beam, and during the electrophoresis process, the movement range of the engine hood is limited, the number of movements is reduced, and the automobile engine hood is prevented from being greatly flipped and the gap between the engine hood and the front fender is improperly maintained, and the electrophoresis quality is high; it can be repeatedly installed and disassembled.

[0009] Patent document 2 (CN212560485U) The utility model relates to an anti-deformation tooling and an anti-deformation device for engine hood painting. During the assembly process, one end of the support structure is installed on the bearing seat; then the main part of the part to be processed is installed on the other end of the support structure, so that the part to be processed is stably supported on the bearing seat; then, one end of the tensioning piece is connected to the bearing seat, and then the other end of the tensioning piece is connected to the modeling part of the part to be processed, so that the tensioning piece is in a tensioned state between the modeling part and the bearing seat. When the part to be processed undergoes corresponding processes, such as electrophoretic coating, surface heat treatment, etc., the modeling part is subjected to the force of the tensioning piece to maintain the original structural form, so that the internal stress cannot be released, and the modeling part is effectively prevented from rebounding and deforming, which greatly meets the modeling requirements of customers. At the same time, the anti-deformation tooling has a simple structure and is easy to use. It does not require the investment of baking, stamping and other equipment, which effectively reduces the investment cost of processing the part to be processed.

[0010] Patent Document 3 (CN207955798U) The utility model discloses a support device for an engine hood, comprising a support rod and a sleeve, wherein the sleeve is arranged at a preset position on the rod body of the support rod, and a clamping portion for fixing with the inner wall of the sleeve is arranged on the circumferential outer wall at the preset position. The support device for the engine hood provided by the utility model is provided with a clamping connection method at the clamping point of the support rod and the sleeve, which effectively avoids the situation that the support rod and the sleeve are unstuck due to the connection method of connecting the support rod and the sleeve with glue in the prior art, and has a more stable connection form, so that the user will not cause the support rod and the sleeve to be unstuck during use. At the same time, this connection form is simple to install, which brings great convenience to the enterprise and improves the installation efficiency. .

[0011] Searching the patent literature shows that there is no patent related to this invention:

[0012] Patent document 1 describes a support device for the engine hood during electrophoresis of a car. This patent does not involve the design content and patent protection content of the support device.

[0013] Patent document 2 describes a device for supporting the engine hood during electrophoresis of a car to prevent the engine hood from deforming, which has little relevance to the deformation measurement point arrangement scheme, measurement scheme, and test tooling of this patent.

[0014] The design scheme of the supporting structure of the engine hood described in Patent Document 3 has low relevance to the present invention. Summary of the invention

[0015] The present invention solves the technical problem of accurately measuring the local deformation of the front and rear ends of the automobile engine hood by electrophoresis, and provides support for improving the accuracy of CAE analysis and obtaining the overall deformation. The present invention provides a method for testing the deformation of the front and rear engine hood of an automobile by electrophoresis.

[0016] There is no testing scheme before the present invention, and the present invention is the first application. The method of the present invention has high measurement accuracy, and the measuring device is convenient and detachable, which is conducive to the operation on the coating site, does not affect the coating production, and has strong work convenience.

[0017] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0018] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0019] A method for testing deformation of front and rear engine hoods of automobiles by electrophoresis, characterized in that:

[0020] Deformation test point arrangement plan: The deformation test points of the hood sheet metal are distributed on the front edge of the hood, combining equal spacing with unequal spacing, and symmetry with dispersion;

[0021] Deformation measurement scheme for engine hood sheet metal during electrophoresis process: The deformation measurement of each measuring point adopts two direct measurement methods.

[0022] Furthermore, the deformation test point arrangement scheme includes the following specific contents:

[0023] With the Y-axis symmetry plane of the vehicle as the center, at least two pairs of symmetrical measuring points are arranged on the front edge of the engine hood, and at least two scattered or asymmetrical measuring points are arranged on each side. The distance between the measuring points shall not be less than 100mm.

[0024] Furthermore, the specific contents of the deformation measurement scheme are as follows:

[0025] Use the upper part of the engine hood support fixture 1 to install the deformation measuring tool. Before electrophoresis, use a caliper or feeler gauge to directly measure the gap between the deformation measuring point on the edge of the engine hood and the measuring tool. During electrophoresis, remove the deformation measuring tool. After electrophoresis, install the deformation measuring tool in situ again, and measure the gap between the deformation test point and the deformation measuring tool again. The difference between the two gaps is the deformation of the engine hood before and after electrophoresis.

[0026] Furthermore, the deformation measurement tooling consists of a connector and a reference beam. The connector is fixed by using the holes at both ends of the reference beam supported by the engine hood during electrophoresis. The length direction of the connector ensures that after being connected to the reference beam, the center line of the reference beam section is directly below the front edge of the engine hood.

[0027] Furthermore, the connector is connected to the reference beam as a long hole, and the two holes are fixed to ensure that the reference beam will not have a torsional deviation in the Y direction.

[0028] Furthermore, there are four threaded holes on the four sides of the long hole of the connector, and four M6 bolts are installed on the threaded holes to adjust the reference beam in the Z direction.

[0029] Furthermore, the reference beam is made of 40×40 aluminum profile, and the connecting part between the aluminum profile and the connector is a bottom profile groove, which provides conditions for Y-axis adjustment of the reference beam.

[0030] Furthermore, a gap is left between the upper surface of the reference crossbeam and the front edge of the engine hood, and the length of the reference crossbeam is designed to be equal to the front edge of the engine hood.

[0031] Further, the length of the connector is 100 mm, and the length ensures that after being connected to the reference beam, the center line of the cross section of the reference beam is directly below the front edge of the engine hood;

[0032] The connector has a width of 100 mm and a thickness of 20 mm.

[0033] Furthermore, the connector is provided in two pieces.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The method of the invention has high measurement accuracy, and the measuring device is convenient and detachable, which is conducive to on-site painting operation, does not affect the painting production, and has strong work convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below in conjunction with the accompanying drawings:

[0037] Figure 1 The schematic diagram of the arrangement of the engine hood deformation measurement points;

[0038] Figure 2 It is a schematic diagram of the deformation test scheme;

[0039] Figure 3a This is the front view of the deformation measurement tooling structure;

[0040] Figure 3b This is a top view of the deformation measurement tooling structure;

[0041] Figure 3c This is the side view of the deformation measurement tooling structure;

[0042] Figure 4 This is a schematic diagram of the connector size scheme.

[0043] In the figure:

[0044] 1. Support fixture; 2. Car body; 3. Engine hood; 4. Reference beam; 5. Connector; 6. Bolt; 7. Slotted hole; 8. Threaded hole. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the implementation of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail below in conjunction with the drawings in the embodiment of the present invention. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings.

[0046] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present invention.

[0047] The present invention is described in detail below in conjunction with the accompanying drawings:

[0048] In view of the above-mentioned needs, an object of the present invention is to provide a method for testing the deformation of an engine hood during electrophoresis of an automobile.

[0049] The technical solution of the present invention is achieved in this way:

[0050] Firstly, a plan for the arrangement of deformation measurement points on the engine hood was proposed. Then, a deformation measurement plan was proposed in combination with the electrophoresis production process requirements. The deformation measurement tooling was designed and trial-produced to complete the deformation measurement work.

[0051] The arrangement scheme of deformation measuring points is the premise of the present invention. During electrophoresis, the rear end of the hood is fixedly mounted on the vehicle body by a hinge, and the front end is loosely connected to the vehicle body by a supporting fixture. The hood is a cantilever structure under the impact of the electrophoresis liquid. The front end of the cantilever, that is, the front edge of the hood, is deformed the most, and the test error has the least impact on the accuracy, so the front edge of the hood is selected to test the deformation. In order to obtain more deformation data, multiple measuring points are set on the front edge of the hood, and a combination of equal spacing and unequal spacing, symmetry and dispersion is adopted. With the Y-axis symmetry plane of the whole vehicle as the center, at least two pairs of symmetrical measuring points are arranged on the front edge of the hood, and at least two scattered / asymmetric measuring points are arranged on each side, and the distance between the measuring points is not less than 100mm. For the arrangement scheme of measuring points with equal spacing and symmetrical arrangement, the deformation can be analyzed for test errors, and the errors can be reduced by mathematical analysis and calculation methods. The arrangement scheme of measuring points with unequal spacing and dispersion increases the number of measuring points, and multiple measuring points are conducive to verifying the accuracy of the CAE analysis model.

[0052] The deformation measurement of each measuring point adopts two direct measurement methods. The deformation measuring tool is installed on the upper part of the engine hood support fixture. Before electrophoresis, the gap between the deformation measuring point on the edge of the engine hood and the measuring tool is directly measured with a caliper / feeler gauge. The tool is removed for electrophoresis, and the gap is measured again after electrophoresis. The difference between the two gaps is the deformation of the engine hood. This solution can be quickly disassembled and reset without affecting the electrophoresis process. The tool uses the two holes on the upper part of the engine hood support fixture. It consists of two parts-reference beams and connectors. Two connectors are designed. The connectors connect and fix the reference beams. It has the characteristics of easy disassembly. It is installed and calibrated before entering the electrophoresis, and removed after the calibration is completed. Wait for the electrophoresis of the engine hood to be completed before reinstalling and calibrating. Since the tool needs to be loaded and unloaded twice before and after electrophoresis, the connector and the reference beam need to be adjusted in the three directions of X, Y, and Z. The reference beam is adjusted before and after installation to ensure that the spatial position of the reference beam and the front edge of the engine hood before and after electrophoresis is consistent. The reference position points are marked on the reference beam, corresponding one to one with the arrangement plan of the deformation measurement points of the engine hood.

[0053] The tooling must be easy to assemble and disassemble and relatively rigid, so some structural and dimensional designs were made. There is a connector at each end of the reference beam. The length of the connector is 100mm. The length ensures that after connecting with the reference beam, the center line of the reference beam section is directly below the front edge of the engine hood, which is convenient for the measuring instrument to measure the front edge of the engine hood vertically. The connector is 60mm wide and 20mm thick. It has a thin plate structure of about 1.5mm relative to the engine hood. It has high rigidity to ensure that there will be no deformation when connecting the reference beam and measuring. The connector is connected to the reference beam through an 8×25mm long hole. The two-hole connection is to ensure that the beam will not have Y-direction torsional displacement. The long hole is used to fine-tune the reference beam in the X direction when installing before and after entering the electrothermal tank. There are four M6 threaded holes on the four sides of the connector long hole, and four M6 30mm long bolts are installed on the threaded holes to adjust the reference beam in the Z direction. The reference beam is made of 40×40 aluminum profile, which can provide sufficient rigidity, and the reference surface of the profile has good flatness and high measurement accuracy. At the same time, the groove of the profile can provide conditions for the Y-axis adjustment of the reference beam. The length of the profile is designed to be equal to the front edge of the engine hood.

[0054] The specific implementation scheme is described in detail below with reference to the accompanying drawings:

[0055] Figure 1 The arrangement plan of the measurement points for deformation of the engine hood is as follows: at the front edge of the engine hood 1, with the Y-axis symmetry plane 3 of the vehicle as the center, 5 measurement points 2 (including 2 groups of symmetrical measurement points) are arranged on the front edge of the engine hood, and 2 scattered / asymmetric measurement points 2 are arranged on each side, and the distance between every two measurement points is not less than 100 mm.

[0056] Figure 2 Deformation test plan, the body and the hood support fixture 1 are electrophoresed together, the upper part of the hood support fixture 1 is fixedly connected to the hood 3, and the lower part is connected to the body 2 socket. The deformation measurement tool is installed on the upper part of the hood support fixture. The tool uses the two holes on the upper end of the hood support fixture and consists of two parts - the reference beam and the connector (see Figure 3a , Figure 3b , Figure 3c ), the connector connects and fixes the reference beam, which is easy to disassemble. It is installed and calibrated before entering the electrophoresis, and removed after the calibration is completed. Wait for the electrophoresis of the engine hood to be completed before reinstalling and calibrating. Since the tooling needs to be loaded and unloaded twice before and after electrophoresis, the connector and the reference beam need to be adjustable in the three directions of X, Y, and Z. Adjust the position of the reference beam before and after installation to ensure that the spatial position of the reference beam before and after electrophoresis is consistent with the front edge of the engine hood. The reference position points are marked on the reference beam, which correspond one by one to the layout plan of the deformation measurement points of the engine hood.

[0057] Figure 3 Deformation measurement fixture scheme, the reference beam 1 and the front edge of the engine hood are basically in the same position in the X direction, and there is a gap in the Z direction. The change in the Z direction gap before and after electrophoresis is the deformation of the engine hood. Figure 4 ) can be adjusted forward and backward and left and right on the reference beam 4. Each connector has four M6 bolts 6 to achieve fine adjustment of the Z-direction distance between the reference beam and the engine hood. The deformation measurement tooling solution can achieve installation adjustment with the engine hood in the X, Y, and Z directions.

[0058] Figure 4 Connector size scheme, slotted hole 7 ensures that the connector and the reference beam are adjusted in the X direction, and threaded hole 8 ensures that the connector and the reference beam are adjusted in the Z direction

[0059] (1) Layout of measurement points for deformation of hood sheet metal during automobile electrophoresis process

[0060] The deformation measurement points of the sheet metal of the engine hood during the electrophoresis process affect the CAE analysis model verification and directly affect the analysis accuracy. The present invention proposes to distribute the deformation test points on the front edge of the engine hood, combining equal spacing with unequal spacing, and symmetry with dispersion. With the Y-axis symmetry plane of the vehicle as the center, at least two pairs of symmetrical measurement points are arranged on the front edge of the engine hood, and at least two scattered / asymmetric measurement points are arranged on each side, with the distance between the measurement points not less than 100mm. The deformation of the front edge is the largest, which is conducive to reducing errors. In the arrangement of measurement points with equal spacing and symmetrical arrangement, the deformation can be used to analyze the test error, and the error can be reduced through mathematical analysis and calculation methods. The unequal spacing and scattered arrangement of measurement points increase the number of measurement points, and multiple measurement points are conducive to verifying the accuracy of the CAE analysis model.

[0061] (2) Measurement of deformation of the hood sheet metal during the electrophoresis process

[0062] The scheme for measuring the deformation of the hood sheet metal during electrophoresis uses a two-time direct measurement method. The deformation measuring tool is installed on the upper part of the hood support fixture. Before electrophoresis, a caliper / feeler gauge is used to directly measure the gap between the deformation measuring point on the edge of the hood and the measuring tool. During electrophoresis, the deformation measuring tool is removed. After electrophoresis, the tool is installed in situ again, and the gap between the deformation measuring point and the measuring tool is measured again. The difference between the two gaps is the deformation of the hood before and after electrophoresis. The scheme can be implemented quickly without affecting the electrophoresis process.

[0063] (3) Coordination relationship between components of the deformation measurement device

[0064] The deformation measurement device consists of a connector and a reference beam. The connector is fixed by using the holes at both ends of the beam of the engine hood support fixture during electrophoresis. The length direction of the connector ensures that after connecting with the reference beam, the center line of the reference beam section is directly below the front edge of the engine hood. The connector and the reference beam are connected as a long hole. The two holes are fixed to ensure that the beam will not have a torsional deviation in the Y direction. There are four threaded holes on the four sides of the connector long hole, and four M6 bolts are installed on the threaded holes to adjust the reference beam in the Z direction. The reference beam is made of 40×40 aluminum profiles. The connection between the profile and the connector is the bottom profile groove, which can provide conditions for the Y-direction adjustment of the reference beam. There is a gap between the upper surface of the profile and the front edge of the engine hood, and the length of the profile is designed to be equal to the front edge of the engine hood.

[0065] (4) Dimensional relationships and requirements of the components of the deformation measurement device

[0066] The length of the connecting machine is 100mm, which ensures that after connecting with the reference beam, the center line of the reference beam section is directly below the front edge of the engine hood. The connector is 100mm wide and 20mm thick, providing sufficient rigidity to ensure that there will be no deformation when connecting the reference beam and measuring. The connector is connected to the reference beam with two 8×25mm long holes. The two-hole connection is to ensure that the beam will not have Y-direction torsional deviation. There are four M6 threaded holes on the four sides of the connector long hole, and four M6 30mm long bolts are installed on the threaded holes to adjust the reference beam in the Z direction. The reference beam is made of 40×40 aluminum profiles. The 40×40 aluminum profiles can provide sufficient rigidity, and the reference surface of the profile has good flatness and high measurement accuracy. At the same time, the groove of the profile can provide conditions for the Y-direction adjustment of the reference beam.

[0067] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent replacement and improvement made by any person skilled in the art within the technical scope disclosed by the present invention and within the spirit and principle of the present invention shall be covered within the protection scope of the present invention. At the same time, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

Claims

1. A method for testing the deformation of the front and rear hood of an automobile by electrophoresis, characterized in that: Deformation test point arrangement plan: The deformation test points of the hood sheet metal are distributed on the front edge of the hood, combining equal spacing with unequal spacing, and symmetry with dispersion; The scheme for measuring the deformation of the engine hood sheet metal during the electrophoresis process: The deformation measurement of each measuring point adopts two direct measurement methods; The deformation test point arrangement scheme includes the following specific contents: With the Y-axis symmetry plane of the vehicle as the center, at least two pairs of symmetrical measuring points are arranged on the front edge of the engine hood, and at least two scattered or asymmetrical measuring points are arranged on each side. The distance between the measuring points is not less than 100mm; The specific contents of the deformation measurement scheme are as follows: The deformation measuring tool is installed on the upper part of the engine hood support fixture (1), and the gap between the deformation measuring point on the edge of the engine hood and the measuring tool is directly measured with a caliper or a feeler gauge before electrophoresis. The deformation measuring tool is removed during electrophoresis, and the deformation measuring tool is installed again in situ after electrophoresis. The gap between the deformation test point and the deformation measuring tool is measured again, and the difference between the two gaps is the deformation amount of the engine hood before and after electrophoresis; The deformation measurement tooling consists of a connector and a reference beam. The connector is fixed by using the holes at both ends of the reference beam supported by the engine hood during electrophoresis. The length direction of the connector ensures that after being connected to the reference beam, the center line of the reference beam section is directly below the front edge of the engine hood.

2. The method for testing deformation of front and rear hoods of automobiles by electrophoresis according to claim 1, characterized in that: The connector is connected to the reference beam as a long hole, and the two holes are fixed to ensure that the reference beam will not have a torsional deviation in the Y direction.

3. The method for testing deformation of front and rear hoods of an automobile by electrophoresis according to claim 2, characterized in that: There are four threaded holes on the four sides of the long hole of the connector, and four M6 bolts are installed on the threaded holes to adjust the reference beam in the Z direction.

4. The method for testing deformation of front and rear hoods of an automobile by electrophoresis according to claim 3, characterized in that: The reference beam is made of 40×40 aluminum profile, and the connecting part between the aluminum profile and the connector is the bottom profile groove, which provides conditions for the Y-direction adjustment of the reference beam.

5. The method for testing deformation of front and rear hoods of automobiles by electrophoresis according to claim 4, characterized in that: There is a gap between the upper surface of the reference crossbeam and the front edge of the engine hood, and the length of the reference crossbeam is designed to be equal to the front edge of the engine hood.

6. The method for testing deformation of front and rear hoods of an automobile by electrophoresis according to claim 5, characterized in that: The length of the connector is 100 mm, and the length ensures that after being connected to the reference beam, the center line of the reference beam section is directly below the front edge of the engine hood; The connector has a width of 100 mm and a thickness of 20 mm.

7. The method for testing deformation of front and rear hoods of an automobile by electrophoresis according to claim 6, characterized in that: The connector is provided in two pieces.

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