Structure and method for preventing back door outer plate from stress deformation

Abstract

The invention discloses a structure and method for preventing a back door outer plate from stress deformation, and relates to the technical field of automobile trunk lids, the structure for preventing the back door outer plate from stress deformation comprises an inner plate, an outer plate and an expansion piece, the inner plate is provided with a plurality of supporting legs in an extending mode in the first direction, the outer plate is connected with the inner plate through an edge covering technology, and the expansion piece is arranged on the outer plate. The supporting legs are arranged on the outer plate and located on one side of the inner plate in the first direction, and the expansion pieces are arranged on the supporting legs and located between the supporting legs and the outer plate. Through the combination of the rigid supporting legs and the expandable filling medium, a multi-stage pressure transmission path is constructed. The supporting legs bear main loads, the expansion pieces compensate assembly gaps and absorb impact energy, and the surface tensile stress of the outer plate is effectively reduced through the synergistic effect of the supporting legs and the expansion pieces.

Description

Technical Field

[0001] The present invention relates to the technical field of structures and methods for preventing a back door outer panel from being deformed by force, and in particular to a structure and method for preventing a back door outer panel from being deformed by force. Background Art

[0002] The trunk lid weldment includes the steel plate near the outside of the trunk. Its edges are connected to the inner panel via hemming, and its center is connected to the inner panel via adhesive coating. The steel plate near the inside of the trunk features support legs that support the outer panel. The inner panel will be used to mount the trunk support bar, trunk lid stopper, trunk lid sealing strip, trunk lock, and trunk lid trim.

[0003] When the trunk is closed, the inner panel will be subjected to pressure from the locking mounting parts. The pressure on the inner panel of the trunk lid is transmitted to the outer panel of the trunk lid through the glue between the inner and outer panels, causing the surface of the outer panel to deform under tension and produce the appearance of the pit. Summary of the Invention

[0004] The main purpose of the present invention is to provide a structure and method for preventing the outer panel of a back door from being deformed by force, so as to prevent the outer panel surface from being deformed by tension, thereby preventing the appearance of a pit.

[0005] To achieve the above objectives, the present invention proposes a structure and method for preventing deformation of a back door outer panel under stress, including:

[0006] The inner plate is provided with a plurality of supporting legs extending along a first direction;

[0007] an outer plate connected to the inner plate through an edge binding process and located on one side of the inner plate in the first direction;

[0008] The expansion piece is provided on the supporting leg and is located between the supporting leg and the outer plate.

[0009] Preferably, the expansion sheet is a thermosetting foaming material, which is a solid sheet structure in an unfoamed state and forms a non-sticky filling body after baking.

[0010] Preferably, a gap is provided between the expansion sheet and the outer panel.

[0011] Preferably, the supporting leg comprises a connecting portion extending along the first direction and a bent mounting portion, and the expansion piece is detachably provided on a side of the mounting portion away from the connecting portion.

[0012] Preferably, the length of the expansion piece is greater than the length of the mounting portion; and / or,

[0013] The width of the expansion piece is greater than the width of the mounting portion.

[0014] In addition, to achieve the above-mentioned purpose, the present invention also proposes a method for preventing the back door outer panel from being deformed by force, comprising the following steps:

[0015] Place the expansion piece in the gap between the inner panel's support legs and the outer panel;

[0016] The expansion sheet is baked to foam and fill the gap.

[0017] Preferably, the baking treatment is performed at a temperature of 80° C. to 150° C. for 10 to 30 minutes, and the volume expansion rate of the expanded sheet after foaming is greater than 200%.

[0018] Preferably, the expansion sheet is pre-cut into a sheet before baking, and the thickness of the expansion sheet is smaller than the gap between the support leg and the outer panel.

[0019] Preferably, a guide groove is processed on a side of the supporting leg facing the outer plate.

[0020] Preferably, the guide groove contacts the foamed expansion sheet to evenly disperse the pressure toward the outside of the trunk.

[0021] In the technical solution provided by the present invention, the inner panel is provided with multiple support legs extending along a first direction. The outer panel is connected to the inner panel through a hemming process and is located on one side of the inner panel in the first direction. The expansion sheet is provided on the support legs and located between the support legs and the outer panel. The combination of rigid support legs and expandable filling medium creates a multi-stage pressure transmission path. The support legs bear the primary load, while the expansion sheet compensates for assembly gaps and absorbs impact energy. The synergistic effect of the two effectively reduces tensile stress on the outer panel surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0023] Figure 1 A perspective diagram of a first embodiment of the structure for preventing deformation of a back door outer panel under stress provided by the present invention;

[0024] Figure 2 for Figure 1 A side view schematic diagram of the structure for preventing the back door outer panel from being deformed by force;

[0025] Figure 3 Schematic diagram of the flow chart of the first embodiment of the method for preventing the back door outer panel from being deformed by force according to the present invention.

[0026] Description of Figure Numbers:

[0027] 1. Outer plate; 2. Inner plate; 3. Support legs; 4. Expansion plate.

[0028] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0031] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0032] The steel plate near the trunk's exterior is connected to the inner panel 2 via hemming, and the center section is secured with glue. Components such as struts, stoppers, and sealing strips are mounted on the inner panel 2. When the trunk is closed, the pressure applied by the locking mechanism is transmitted through the inner panel 2 to the outer panel 1. Because the load is transferred between the inner and outer panels solely through the glue layer, the outer panel 1 experiences uneven tension, which can easily lead to localized dents and deformation after prolonged use.

[0033] The present invention provides a structure and method for preventing the back door outer panel 1 from being deformed by force. Figures 1 to 3 This is an embodiment of the structure and method for preventing the back door outer panel 1 from being deformed by force provided by the present invention.

[0034] Please also refer to Figures 1 to 2The structure for preventing the back door outer panel 1 from being deformed by force includes an inner panel 2, an outer panel 1 and an expansion piece 4, wherein the inner panel 2 is provided with a plurality of support legs 3 extending along a first direction, the outer panel 1 is connected to the inner panel 2 through a edging process, and is located on one side of the inner panel 2 in the first direction, and the expansion piece 4 is arranged on the support leg 3 and is located between the support leg 3 and the outer panel 1.

[0035] The support leg 3 refers to a protruding structure extending from the main body of the inner panel 2. It can be manufactured using a stamping process and is used to provide support perpendicular to the panel surface. The hemming process involves bending the edge of the outer panel 1 inward to wrap around the inner panel 2. This can be achieved using mechanical pressing equipment to form a stable edge connection. The expansion sheet 4 refers to a filler material placed on the top surface of the support leg 3. It can be a preformed sheet that expands upon heat to fill the space between the support leg 3 and the outer panel 1.

[0036] Specifically, the inner panel 2 extends toward the outer panel 1 via multiple spaced-apart support legs 3. This hemming connection ensures the rigid fixation of the edges of the outer and inner panels 1 and 2. A solid expansion sheet 4 is placed between the top of the support legs 3 and the inner surface of the outer panel 1. During the subsequent baking process, this expansion sheet 4 expands in volume, forming a filler layer that closely contacts the inner surface of the outer panel 1. When an external force acts on the inner panel 2, the load is transferred through the support legs 3 to the expansion sheet 4, which then evenly distributes the pressure across the surface of the outer panel 1, preventing localized stress concentration.

[0037] Therefore, in the technical solution provided by the present invention, the inner panel 2 is provided with multiple support legs 3 extending along a first direction. The outer panel 1 is connected to the inner panel 2 through a hemming process and is located on one side of the inner panel 2 in the first direction. The expansion sheet 4 is provided on the support legs 3 and located between the support legs 3 and the outer panel 1. The combination of rigid support legs 3 and expandable filling medium establishes a multi-stage pressure transmission path. The support legs 3 bear the primary load, while the expansion sheet 4 compensates for assembly clearance and absorbs impact energy. The synergistic effect of the two effectively reduces the tensile stress on the surface of the outer panel 1.

[0038] In traditional solutions, viscous colloids or elastic gaskets are used to fill the gaps. The former will bond with the outer panel 1 after curing, making maintenance difficult, while the latter cannot effectively transmit pressure due to elastic deformation. This solution uses the physical support of a non-viscous filler to avoid material residue while establishing a stable pressure transmission path.

[0039] Specifically, in the embodiment of the present invention, the expansion sheet 4 is a thermosetting foam material, which is a solid sheet structure in an unfoamed state and forms a non-sticky filling body after baking.

[0040] A thermosetting foam material refers to a polymer material that undergoes a chemical cross-linking reaction and expands upon heating. Specifically, this can be achieved using epoxy resin-based foam materials, whose chemical structure is irreversible after curing. A solid sheet structure in an unfoamed state refers to a thin sheet of material that maintains a preset shape and size at room temperature. This can be achieved through die-cutting or calendering processes, facilitating assembly to the surface of the support leg 3. The non-sticky filler formed after baking refers to an expanded body that does not produce adhesion after the material foams but can completely fill the gap. This can be achieved by controlling the decomposition temperature and cross-linking density of the foaming agent to avoid adhesion to the outer panel 1.

[0041] Furthermore, a gap is provided between the expansion sheet 4 and the outer panel 1 .

[0042] The gap refers to the space between the expansion sheet 4 and the inner surface of the outer panel 1 where there is no contact. Specifically, this can be achieved by adjusting the height of the support leg 3 or the thickness of the expansion sheet 4, and is used to prevent the expansion sheet 4 from directly contacting the outer panel 1 when it is not foamed. The expansion sheet 4 refers to a thermosetting material in a solid sheet state in an unfoamed state. Specifically, it can be achieved by using a polyurethane foam material or an epoxy resin foam material. After baking, the volume expands to form a filling body. The mounting portion of the support leg 3 is fixedly connected to the expansion sheet 4 during assembly. At this time, the expansion sheet 4 is in a solid sheet state when it is not foamed, and its thickness is less than the vertical distance between the top of the support leg 3 and the inner side of the outer panel 1, thereby forming a gap between the two. When baking, the expansion sheet 4 foams due to heat and its volume increases, gradually filling the gap space and abutting the inner side of the outer panel 1, eventually forming a pressure transmission path.

[0043] The supporting leg 3 includes a connecting portion extending along a first direction and a bent mounting portion, and the expansion piece 4 is detachably provided on a side of the mounting portion away from the connecting portion. The supporting leg 3 includes a connecting portion extending along a first direction and a bent mounting portion, and the expansion piece 4 is detachably provided on a side of the mounting portion away from the connecting portion. This arrangement ensures the structural strength while allowing the expansion piece 4 to be independently maintained and replaced according to wear conditions.

[0044] The connecting part refers to the base structure extending along the length direction of the inner panel 2, which can be realized by stamping and forming the inner panel 2 in one piece, and is used to support the mounting part and disperse the force. The mounting part refers to the supporting structure formed by the bending process, which can be realized by bending the end of the connecting part at a right angle using a bending machine, and is used to provide an installation plane for the expansion piece 4. The detachable setting refers to a non-fixed connection relationship between the expansion piece 4 and the mounting part, which can be realized by a snap-on structure or magnetic adsorption, so that the expansion piece 4 can be replaced separately during maintenance.

[0045] Furthermore, the length of the expansion piece 4 is greater than the length of the mounting portion. The length of the expansion piece 4 is greater than the length of the mounting portion.

[0046] The width of the expansion piece 4 is greater than the width of the mounting portion. The width refers to the dimension perpendicular to the extension direction of the support leg 3, which can be determined by measuring the maximum span of the mounting portion in this direction to match the coverage of the expansion piece 4 in this direction.

[0047] After the mounting portion is formed through the bending process, the expansion sheet 4 is fixed to the side of the mounting portion away from the connection portion. Because the length and width of the expansion sheet 4 exceed the corresponding dimensions of the mounting portion, the expansion sheet 4 can completely cover the edge area of the mounting portion before foaming. During the baking process, the expansion sheet 4 expands outward in the length and width directions. The foamed filling body not only covers the entire surface of the mounting portion, but also extends to the support leg 3 area outside the mounting portion, forming a continuous support interface. As a result, the pressure exerted on the outer panel 1 is evenly transmitted to the entire mounting portion and adjacent areas of the support leg 3 through the expansion sheet 4, avoiding deformation caused by local stress concentration.

[0048] refer to Figure 3 FIG3 is a flow chart of a first embodiment of a method for preventing a back door outer panel 1 from being deformed by force according to the present invention.

[0049] Step S10: processing a guide groove on the side of the support leg 3 facing the outer panel 1 .

[0050] A guide groove is a groove or channel structure formed on the side of the support leg 3 facing the outer panel 1. This can be achieved through stamping, milling, or laser cutting, and can be linear, wavy, or grid-like. The guide groove guides the flow of the foamed material and creates multiple points of contact, thereby expanding the pressure distribution area. Physical filling involves the expansion of the expansion sheet 4 after foaming to create space between the support leg 3 and the outer panel 1. This can be achieved using closed-cell foam or a non-sticky elastomer. It establishes a pressure transmission interface through non-adhesive mechanical filling to avoid stress concentration.

[0051] Specifically, a guide groove is processed on the side of the support leg 3 facing the outer panel 1. When the expansion sheet 4 foams between the support leg 3 and the outer panel 1, the foaming material will expand and fill along the extension direction of the guide groove. The expansion body forms a surface contact with the side wall of the guide groove, and the elastic deformation ability of the foaming material enables it to adapt to the contour changes of the guide groove. When an external force acts on the inner panel 2, the pressure is transmitted to the foam expansion sheet 4 through the support leg 3, and then dispersed to different areas of the outer panel 1 through the contact surface between the guide groove and the outer panel 1. The existence of the guide groove expands the pressure transmission path from a single point contact to a linear or mesh distribution extending along the groove body.

[0052] Step S20: placing the expansion sheet 4 in the gap between the support leg 3 of the inner panel 2 and the outer panel 1;

[0053] The pre-cut sheet expansion sheet 4 is placed in the gap between the support leg 3 and the outer panel 1. The size of the gap can be slightly larger than the original thickness of the expansion sheet 4 to ensure that the expansion sheet 4 has enough space to extend during the subsequent baking process.

[0054] Step S30: baking the expansion sheet 4 to make it foam and fill the gaps;

[0055] By controlling the baking temperature and time, the material expands and completely fills the gap space. The foamed material forms a non-viscous filling body. The extrusion force generated by its volume expansion contacts the inner side of the outer panel 1, and the guide groove structure converts the local concentrated pressure into surface pressure for transmission.

[0056] The temperature of the baking treatment refers to the thermal energy range required for the expansion sheet 4 to undergo a foaming reaction, which can be achieved by using an electric oven or hot air circulation equipment. This temperature range can not only ensure the foaming efficiency, but also prevent the surface coating of the outer panel 1 from being damaged due to overheating. The time of the baking treatment refers to the continuous heating time required for the expansion sheet 4 to complete foaming, which can be precisely adjusted through an automated temperature control system to ensure that the foaming reaction is sufficient and uniform. The volume expansion rate refers to the ratio of the volume of the expansion sheet 4 after foaming to the volume in the unfoamed state, which can be achieved by adjusting the formula ratio of the thermosetting foaming material. The high expansion rate can effectively fill the gap between the support leg 3 and the outer panel 1.

[0057] Specifically, after placing a solid sheet-like expansion sheet 4 in the gap between the support leg 3 and the outer panel 1, the assembled tailgate assembly is placed in a baking machine and heated continuously at a temperature of 80°C to 150°C for 10 to 30 minutes. The expansion sheet 4 expands upon heating, with a volumetric expansion rate exceeding 200% after foaming, completely filling the gap and forming a dense, non-sticky filling structure. This filling sheet is in direct contact with the support leg 3 and the outer panel 1, providing physical support and transferring the pressure exerted on the inner panel 2 to the outer panel 1, preventing the outer panel 1 from deforming due to localized tensile stress.

[0058] Step S40: the guide groove contacts the foamed expansion sheet 4 to evenly distribute the pressure toward the outside of the trunk.

[0059] A guide groove is a groove structure formed on the inner surface of the outer panel 1. It can be machined or stamped to direct the flow of the expansion material. The cross-sectional shape of the guide groove can be U-shaped, V-shaped, or trapezoidal. Its depth and width are designed based on the thickness of the outer panel 1 and the required pressure distribution. The guide groove forms a continuous support structure by varying the filling pattern of the expansion material, thereby optimizing the pressure transmission path.

[0060] Pressure dispersion expands the pressure range through the contact surface between the guide groove and the expansion sheet 4. This is achieved through the contact between the groove surface and the foam material. When the expansion sheet 4 is compressed, the foam material deforms along the extension of the guide groove, converting the concentrated load into a distributed load, effectively reducing the pressure per unit area. This contact method allows the supporting force to be transmitted linearly along the extension of the guide groove, avoiding stress concentration.

[0061] Specifically, an array of parallel guide grooves is machined on the inner surface of the outer panel 1 by CNC milling. The extension direction of the guide groove forms a 45° angle with the arrangement direction of the support legs 3, and the groove spacing is set to be evenly distributed according to the size of the outer panel 1. During the foaming and expansion process, the expansion material fills the interior of the guide groove to form an interlocking structure. When the outer panel 1 is subjected to the impact load when the trunk is closed, the expansion material in the guide groove undergoes elastic deformation, and the pressure is transmitted to the adjacent area along the extension direction of the groove body through the contact surface of the groove wall. This pressure transmission method disperses the stress originally concentrated on the lock installation point to the entire area covered by the guide groove.

[0062] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention description and drawings under the concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A structure for preventing deformation of the back door outer panel under stress, applied to the trunk lid of a car, characterized in that: include: The inner plate is provided with a plurality of supporting legs extending along a first direction; an outer plate connected to the inner plate through an edge binding process and located on one side of the inner plate in the first direction; The expansion piece is provided on the supporting leg and is located between the supporting leg and the outer plate.

2. The structure for preventing the back door outer panel from being deformed by force according to claim 1, characterized in that: The expansion sheet is a thermosetting foaming material, which is a solid sheet structure in the unfoamed state and forms a non-sticky filling body after baking.

3. The structure for preventing deformation of the back door outer panel according to claim 1, characterized in that: A gap is provided between the expansion sheet and the outer plate.

4. The structure for preventing deformation of the back door outer panel under stress according to claim 1, characterized in that: The supporting leg includes a connecting portion extending along a first direction and a bent mounting portion, and the expansion piece is detachably mounted on a side of the mounting portion away from the connecting portion.

5. The structure for preventing deformation of the back door outer panel according to claim 4, characterized in that: The length of the expansion piece is greater than the length of the mounting portion; and / or, The width of the expansion piece is greater than the width of the mounting portion.

6. A method for preventing deformation of a back door outer panel due to stress, characterized in that: The following steps are involved: Place the expansion piece in the gap between the inner panel's support legs and the outer panel; The expansion sheet is baked to foam and fill the gap.

7. The method for preventing deformation of a back door outer panel under stress according to claim 6, characterized in that: The baking treatment is performed at a temperature of 80° C. to 150° C. for 10 to 30 minutes, and the volume expansion rate of the expanded sheet after foaming is greater than 200%.

8. The method for preventing deformation of a back door outer panel under stress according to claim 6, wherein: The expansion sheet is pre-cut into a sheet before baking, and its thickness is smaller than the gap between the support leg and the outer panel.

9. The method for preventing deformation of a back door outer panel under stress according to claim 6, wherein: The step of placing the expansion sheet in the gap between the support legs of the inner panel and the outer panel also includes: A guide groove is processed on one side of the supporting leg facing the outer plate.

10. The method for preventing deformation of a back door outer panel under stress according to claim 6, wherein: Also includes: The guide groove contacts the foamed expansion sheet to evenly disperse the pressure in the direction of the outer side of the trunk.

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