Method for judging the combination of exterior panels and mastic adhesives

Abstract

To provide a determination method determining an inappropriate combination of an outside plate and a mastic adhesive which causes deformation that impairs designability on the outside plate.SOLUTION: A method for determining a combination of an outside plate and a mastic adhesive comprises: preparing a first member 11 assumed as the outside plate, and a second member 21 assumed as a reinforcing member reinforcing the outside plate; restraining the first and second members 11, 21 with at least two restraining members 40 so that the first and second members 11, 21 are disposed so as to sandwich the mastic adhesive 30 therebetween and the mastic adhesive is disposed between at least two restraining members 40; and heating the mastic adhesive 30 to bond the first member 11 and the second member 21. A deformation volume of the first member 11 caused by heating it when bonded is measured from a side opposite to a side where the second member 21 is located with respect to the bonded first member 11. The combination of the outside plate and the mastic adhesive 30 is determined to be inappropriate when the deformation of the measured first member 11 includes both of positive deformation and negative deformation.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for determining a combination of a vehicle exterior panel and a mastic adhesive. [Background technology]

[0002] Mastic adhesives are used as adhesives for bonding exterior panels of vehicles to reinforcing members that reinforce the exterior panels.

[0003] In recent years, there has been a trend to make the exterior panels etc. used in vehicles thinner in order to reduce the weight of the vehicles, and when the thinner exterior panels etc. are bonded with mastic adhesive, deformation caused by the mastic adhesive is likely to occur in the bonded portion of the exterior panels etc. In order to prevent this deformation from occurring, Patent Document 1 proposes a method for predicting and judging the deformation of the exterior panels etc. when heated and cooled by using a CAE simulation based on the thermal expansion coefficient etc. of the mastic adhesive. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-59887 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, even if the above analysis is performed, it is difficult to predict deformation of the exterior panel because the properties of the mastic adhesive change depending on temperature conditions, etc., and the timing of expansion and contraction of the mastic adhesive, exterior panel, and reinforcing member differs. Also, in an actual vehicle, even a slight deformation can impair the design, and it is difficult to accurately grasp such deformation and select an appropriate combination of the exterior panel and the mastic adhesive.

[0006] The present invention has been made in consideration of the above points, and provides a combination judgment method for judging whether or not a combination of a vehicle outer panel and a mastic adhesive is appropriate. [Means for solving the problem]

[0007] In consideration of the above-mentioned problems, the method of the present invention for determining a combination of an exterior panel and a mastic adhesive includes a preparation step of preparing a first member assumed to be an exterior panel of a vehicle and a second member assumed to be a reinforcing member for reinforcing the exterior panel, a bonding step of arranging the first member and the second member so as to sandwich the mastic adhesive therebetween, restraining the first member and the second member with at least two restraining members so that the mastic adhesive is disposed between the at least two restraining members, and heating the mastic adhesive to bond the first member and the second member, and a bonding step of bonding the first member and the second member to the first member after the bonding step. the measurement step of measuring an amount of deformation of the first member due to heating during the bonding step from the side opposite to the side on which the second member is located; and a determination step of determining that a combination of the outer panel corresponding to the first member and the mastic adhesive is inappropriate if the measurement step includes any one of the following deformations (1) to (3), in which deformation of the first member after heating during the bonding step, relative to the first member before heating during the bonding step, is defined as positive deformation in a direction away from the second member and negative deformation in a direction toward the second member: (1) The deformation of the first member includes both the positive deformation and the negative deformation. (2) The positive deformation is such that the first member has a convex shape as a whole, and is a deformation such that the first member is partially concave with respect to the overall convex shape. (3) The negative deformation is such that the first member has an overall concave shape, and is a deformation such that the first member is partially bulging with respect to the overall concave shape. Effect of the Invention

[0008] According to the present invention, a first member, which is assumed to be an outer panel of a vehicle, and a second member, which is assumed to be a reinforcing member, are arranged so as to sandwich the mastic adhesive. At the same time, the first and second members are restrained by at least two restraining members so that the mastic adhesive is arranged between the at least two restraining members. This makes it possible to simulate a state in which the outer panel of a vehicle and the reinforcing member are arranged so as to sandwich the mastic adhesive, and both ends are restrained. In this state, the mastic adhesive is heated, and the amount of deformation of the first member deformed by heating is measured. This makes it possible to simulate the deformation that actually occurs in the outer panel of a vehicle due to the mastic adhesive, and to measure the amount of deformation.

[0009] Furthermore, among the deformations of the first component caused by heating, the deformations shown in (1) to (3) cause the surface of the first component to have a wavy shape with a mixture of concave and convex parts, which causes a loss of the design of the exterior panel of the vehicle. Therefore, if the deformation of the first component after heating includes any of the deformations shown in (1) to (3), it is determined that the exterior panel and the mastic adhesive are an inappropriate combination.

[0010] As a result, it is possible to determine inappropriate combinations of exterior panels and mastic adhesives that would cause deformations that would detract from the design when bonding the exterior panels of a vehicle to reinforcing members using mastic adhesive. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic perspective view of a roof portion of a vehicle that is to be judged using a method for judging a combination of an exterior panel and a mastic adhesive according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view illustrating a test specimen used in a method for determining a combination of an outer panel and a mastic adhesive according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a flow chart illustrating the steps of a method for determining a combination of an outer panel and a mastic adhesive according to an embodiment of the present invention. [Figure 4]5(a) is a schematic conceptual diagram illustrating a test specimen in a state in which the first and second members are arranged and the first and second members are restrained by two restraining members in the bonding process shown in FIG. 3; (b) is a schematic conceptual diagram illustrating the state of the test specimen immediately after heating in the bonding process shown in FIG. 3; and (c) is a schematic conceptual diagram illustrating the state of the test specimen after a predetermined period of heating has elapsed since immediately after heating in the bonding process shown in FIG. 3. [Diagram 5] FIG. 4 is a schematic conceptual diagram illustrating the measurement process shown in FIG. [Figure 6] 4(a) to (e) are diagrams illustrating an example of the measurement results of the deformation amount of the first member performed in the measurement step shown in FIG. [Figure 7] 1A and 1B are diagrams illustrating the difference in intensity between specularly reflected light and diffusely reflected light when the deformation includes both positive and negative deformations. [Figure 8] 1 is a graph showing the relationship between the temperature and the elapsed time after the first and second members according to Reference Examples 1 and 2 were placed in a drying furnace. [Figure 9] 1 is a graph showing the relationship between the amount of strain (amount of deformation) of the first member and the measurement distance for specimens 1 to 4 under rapid heating conditions and specimens 1 to 4 under gradual heating conditions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of the present invention will be described below with reference to Figures 1 to 7. In the following, a roof panel 101 will be used as an example of an outer panel, but the outer panel is not limited to the roof panel 101 and may be a hood panel, a front fender panel, a side panel, a door panel, or the like.

[0013] A vehicle has a body, which is composed of body panel structures such as a hood, trunk lid, doors, sides, and a roof, and which defines a passenger compartment surrounded by these body panel structures. The body panel structure is assembled, for example, in an automobile production line, by bonding the outer plate of the vehicle to a reinforcing member that reinforces the outer plate with a mastic adhesive 30. The mastic adhesive 30 is applied to the outer plate and the reinforcing member in the automobile production line, and is cured by utilizing heat in a paint baking oven after the outer plate is painted.

[0014] For example, the roof portion of a vehicle 100 shown in Fig. 1 is provided with a roof panel 101 as an outer plate and reinforcements 102 as reinforcing members. A plurality of reinforcements 102 are provided at intervals on the passenger compartment side of the roof panel 101. Both ends of the roof panel 101 and the reinforcements 102 are restrained by side panels 103.

[0015] The reinforcement 102 is made of, for example, metal, and is a reinforcing member that improves the tensile rigidity of the roof panel 101. The reinforcement 102 is adhered to the roof panel 101 via a plurality of mastic adhesives 30 arranged at predetermined intervals. Since the reinforcement 102 is a member that reinforces the roof panel 101, it has a bending rigidity higher than that of the roof panel 101.

[0016] Incidentally, when the roof panel 101 and the reinforcement 102 are bonded together via the mastic adhesive 30, deformation may occur in the bonded portion of the roof panel 101 due to the mastic adhesive 30. However, as will be described later, among the deformations occurring in the bonded portion of the roof panel 101, deformations having a wavy shape may impair the design of the roof panel 101.

[0017] Therefore, in this embodiment's method for determining the combination of an exterior panel and mastic adhesive 30, a test specimen 10 simulating a vehicle 100 is used to measure the surface shape of a first member 11 representing the exterior panel, and it is determined whether the combination of the exterior panel and mastic adhesive 30 is appropriate.

[0018] First, the configuration of the test specimen 10 will be described with reference to FIG. 2, and then a method for determining the combination of the outer panel and the mastic adhesive 30 will be described.

[0019] 1. Test piece 10 As shown in Figure 2, the test specimen 10 comprises a mastic adhesive 30, a first member 11 and a second member 21 arranged to sandwich the mastic adhesive 30, and a restraining member 40 that restrains the first member 11 and the second member 21.

[0020] The mastic adhesive 30 is in contact with a surface of a main body 21a of the second member 21 described below on the side where the first member 11 is located (hereinafter, "front surface 21c of main body 21a") and a surface of the first member 11 on the side where the second member 21 is located (hereinafter, "rear surface 11b of first member 11"). The uncured mastic adhesive 30 in this contact state is cured by heating in a bonding step S2 described below, thereby bonding the first member 11 and the second member 21. In this specification, the same reference numerals are used for both the uncured mastic adhesive and the cured mastic adhesive 30.

[0021] The mastic adhesive 30 includes a thermosetting material and a foaming agent that provides flexibility. The thermosetting material may be a thermosetting resin or a thermosetting rubber, and after hardening, the material becomes compressively elastically deformable. The foaming agent may be an organic foaming agent or an inorganic foaming agent. Furthermore, the mastic adhesive 30 may contain a filler, a crosslinking agent, a softener, etc., as necessary.

[0022] The first member 11 is a member assumed to be an outer plate of the vehicle 100, and is a plate-shaped member. The material of the first member 11 is preferably the same as that of the outer plate, and examples of the material include metals such as aluminum, aluminum alloys, alloys such as steel, and fiber-reinforced plastics (FRP) such as carbon fiber reinforced plastics. The thickness of the first member 11 (plate thickness of the plate-shaped member) is preferably made to correspond to the thickness of the outer plate of the vehicle 100 to be evaluated. As described below, if the combination of the outer plate and the mastic adhesive 30 is determined to be inappropriate, it is possible to change the mastic adhesive 30, but for example, the thickness and material of the outer plate may be changed.

[0023] The second member 21 is assumed to be used as a reinforcing member that reinforces the outer plate of the vehicle 100. The material of the second member 21 is preferably the same as that of the reinforcing member, and an example of the material that can be used is an alloy such as steel.

[0024] The second member 21 is a channel having a U-shaped cross section, and includes a main body portion 21a and reinforcing portions 21b formed on two opposing sides (long sides in FIG. 2) of the main body portion 21a. The pair of reinforcing portions 21b are formed on the two opposing sides of the main body portion 21a so as to stand vertically in the direction opposite to the side on which the first member 11 is located. The reinforcing portions 21b increase the rigidity of the second member 21, and therefore the second member 21 can function as a member that reinforces the first member 11.

[0025] Such second member 21 is formed by bending both sides of a single plate-like member, and the thickness of second member 21 (plate thickness of plate-like member) is preferably equivalent to the same thickness as the reinforcing member. The shape of second member 21 is not particularly limited as long as it improves rigidity, and may be cylindrical, for example. However, in consideration of easily restraining first and second members 11, 21, the shape of second member 21 is preferably the shape shown in FIG. 2.

[0026] Here, when a mastic adhesive is placed between the outer plate and the reinforcing member and heated, the outer plate has a larger surface area and conducts heat more easily. Therefore, in this embodiment, the dimensions, materials, etc. of the first and second members 11, 21 are assumed to be those of the actual outer plate and reinforcing member, so that when the test body 10 is heated, the second member 21 starts thermal expansion later than the first member 11. In other words, when the test body 10 is heated, the first member 11 thermally expands before the second member 21. This makes the first member 11 more likely to deform.

[0027] Specifically, when the material of the second member 21 is different from the material of the first member 11, it is preferable that the thermal expansion coefficient (linear expansion coefficient or volume expansion coefficient) of the material of the second member 21 is smaller than that of the first member 11. On the other hand, when the material of the second member 21 is the same as the material of the first member 11, or when the materials are different but have the same thermal expansion coefficient, it is preferable that the thickness (plate thickness) of the second member 21 is larger than the thickness (plate thickness) of the first member 11. It is assumed that the thicknesses of the first member 11 and the second member 21 correspond to the thicknesses of the outer plate and the reinforcing member, respectively.

[0028] The restraining member 40 includes a bolt 41, a nut 42, and a washer 43 having a hollow portion into which the threaded portion of the bolt 41 is inserted. The washer 43 adjusts the size of the gap between the first member 11 and the second member 21, and is disposed between the first member 11 and the second member 21. The nut 42 is disposed on the surface 11a of the first member 11.

[0029] 2, a first through hole 12 and a second through hole 22 into which a threaded portion of a bolt 41 is inserted are formed on both sides of the first member 11 and the second member 21, respectively. When the first and second members 11, 21 are restrained in the bonding step S2, the threaded portion of the bolt 41 is inserted from the side opposite to the front surface 21c of the main body portion 21a through the second through hole 22, the hollow portion of the washer 43, and the first through hole 12, in that order, and screwed into the nut 42.

[0030] Here, an example is described in which the restraining member 40 is composed of a bolt 41, a nut 42, and a washer 43, but the present invention is not limited to this. Anything that can restrain the first and second members 11, 21 while ensuring a gap between them may be used as the restraining member 40.

[0031] 2. How to judge the combination of exterior panels and mastic adhesive 30 Next, the method of determining the combination of an outer panel and a mastic adhesive according to this embodiment will be described along the steps shown in FIG.

[0032] 2-1. Preparation process S1 In the method for determining a combination of an outer panel and a mastic adhesive 30 according to this embodiment, a preparation step S1 is first performed. In this step, a first member 11 that is assumed to be an outer panel of a vehicle 100 and a second member 21 that is assumed to be a reinforcing member that reinforces the outer panel are prepared. Specifically, the first and second members 11, 21 that constitute the above-mentioned test specimen 10 are prepared (see FIG. 2). The first member 11 and the second member 21 can be used, for example, assuming that they are a roof panel 101 and a reinforcement 102 (see FIG. 1), respectively.

[0033] 2-2. About the adhesion process S2 Next, the bonding step S2 is performed. In this step, as shown in Fig. 4(a), the first member 11 and the second member 21 are arranged so as to sandwich the mastic adhesive 30. At the same time, the first member 11 and the second member 21 are restrained by at least two restraining members 40 so that the mastic adhesive 30 is arranged between the at least two restraining members 40. In this state, as shown in Figs. 4(b) and 4(c), the mastic adhesive 30 is heated to bond the first member 11 and the second member 21.

[0034] When arranging the first and second members 11, 21, uncured mastic adhesive 30 is dot-applied to the surface 21c of the main body 21a of the second member 21. Here, an example is described in which one mastic adhesive 30 is dot-applied to the center of the surface 21c of the main body 21a, but the present invention is not limited to this. The positions and number of dot-applied mastic adhesives 30 may be appropriately set according to the positions and number of mastic adhesives 30 to be applied when bonding the expected roof panel 101 and reinforcement 102.

[0035] After the dot application, the size of the gap between the first and second members 11, 21 is adjusted by the washer 43 so that the back surface 11b of the first member 11 can contact the mastic adhesive 30. After the adjustment, the first member 11 is placed on top of the washer 43 and the mastic adhesive 30 so that the back surface 11b of the first member 11 contacts the washer 43 and the mastic adhesive 30.

[0036] In this overlapping state, both sides of the first and second members 11, 21 are fixed with bolts 41 and nuts 42, and the mastic adhesive 30 is disposed between the two restraining members 40.

[0037] In this embodiment, the first and second members 11, 21 are restrained by at least two restraining members 40 so that the extension of the first member 11 does not escape in the horizontal direction during thermal expansion due to heating. Furthermore, the positions of restraint by the restraining members 40 are set so that the mastic adhesive 30 is disposed between the at least two restraining members 40. This makes it possible to analyze the effect of the mastic adhesive 30 on the deformation of the first member 11.

[0038] In this manner, the test specimen 10 is prepared, in which the uncured mastic adhesive 30 is disposed. This test specimen 10 can simulate a state in which a roof panel 101 and a reinforcement 102 are disposed so as to sandwich the uncured mastic adhesive 30, and both sides of these are restrained by side panels 103 (see FIG. 1).

[0039] After restraining the first and second members 11, 21, and before heating the mastic adhesive 30, the surface shape (surface roughness) of the face of the first member 11 opposite the side on which the second member 21 is located (hereinafter referred to as "surface 11a of the first member 11") is measured (measurement of the surface shape before heating) in the same manner as the method for measuring the surface shape after heating described below.

[0040] When the mastic adhesive 30 is heated, the test specimen 10 is placed in, for example, a drying oven and heated. At this time, it is preferable that the entire test specimen 10 is heated uniformly in the drying oven, assuming a paint baking oven in an automobile production line. By heating, the foaming agent contained in the mastic adhesive 30 foams and the uncured resin hardens, and the mastic adhesive 30 that has completed foaming and hardening is cooled.

[0041] The heating temperature of the mastic adhesive 30 is set appropriately to a temperature at which the mastic adhesive 30 can be hardened and foamed depending on the type of mastic adhesive 30. Note that the heating temperature, the rate at which the temperature is increased until the heating temperature is reached, the time for which the heating temperature is maintained, the cooling temperature, and the rate at which the temperature is decreased until the cooling temperature is reached are preferably set in accordance with the conditions in a paint baking furnace in an actual automobile production line.

[0042] As an example, the heating temperature is, for example, 160° C. or more, or 170° C. or more, and, for example, 200° C. or less, or 190° C. or less. When the temperature is raised rapidly, the heating rate is, for example, 35° C. / min. or more, 40° C. / min. or more, and, for example, 50° C. / min. or less, or 45° C. / min. or less. When the temperature is raised slowly, on the other hand, it is, for example, 3° C. / min. or more, 5° C. / min. or more, and, for example, 15° C. / min. or less, or 10° C. / min. or less. The time for which the heating temperature is maintained is, for example, 10 minutes or more, or 15 minutes or more, and, for example, 40 minutes or less, or 30 minutes or less.

[0043] The cooling temperature is preferably, for example, 60° C. or less, or 50° C. or less. The cooling rate is, for example, 5° C. / min or more, or 10° C. / min or more, and is preferably, for example, 30° C. / min or less, or 25° C. / min or less. In consideration of the implementation of the surface profile measurement described later, it is preferable to allow the test piece 10 to cool after cooling to a temperature at which the surface profile measurement can be performed (for example, room temperature).

[0044] 4(b) and 4(c), a description will be given of an example of deformation of the surface shape of the first member 11. As shown in Fig. 4(b), immediately after heating, the foaming agent contained in the mastic adhesive 30 starts to foam.

[0045] Along with this, in this embodiment, when heated, the first member 11 begins to thermally expand (stretch) in the horizontal direction before the second member 21. However, both sides of the first member 11 are restrained by the restraining members 40, and the horizontal thermal expansion of the second member 21 is slower than that of the first member 11, so the first member 11 deforms in a bulging manner in a direction away from the second member 21.

[0046] Thereafter, the second member 21 also tries to expand horizontally due to thermal expansion to approach the expansion of the first member 11, so that the expansion-like deformation of the first member 11 is suppressed. At this time, depending on the timing of hardening and foaming of the mastic adhesive 30, the mastic adhesive 30 restrains the center of the first member 11, so that the first member 11 may be deformed in a wavy shape as shown in FIG. 4(c). Specifically, a recess 11g is formed in the first member 11 at the bonding portion with the mastic adhesive 30, which is deformed in a direction approaching the second member 21 with respect to the first member 11 before heating. Furthermore, protrusions 11f are formed on both sides of the recess 11g, which are deformed in a direction away from the second member 21 with respect to the first member 11 before heating.

[0047] Here, in this specification, among the deformations of the first member 11 after heating, relative to the first member 11 before heating (see FIG. 4(a)), deformation in a direction away from the second member 21, such as the convex portion 11f, is referred to as positive deformation. On the other hand, among the deformations of the first member 11 after heating, relative to the first member 11 before heating, deformation in a direction approaching the second member 21, such as the concave portion 11g, is referred to as negative deformation.

[0048] Although the case where the first member 11 is deformed in a wavy shape has been described, depending on the material of the mastic adhesive 30, the heating conditions, and the thickness of the first member 11, either positive deformation or negative deformation may occur in the first member 11, as will be described in the examples described later. Also, in Fig. 4(c), the case where the first member 11 is deformed in an M-shape has been described, but the state of deformation differs depending on the position where the mastic adhesive 30 is dot-applied. For example, even in the case of deformation in an S-shape or W-shape, etc., positive deformation and negative deformation are included, so even in this case, the design of the exterior panel is impaired.

[0049] 2-3. Measurement process S3 Next, a measurement step S3 is performed. In this step, as shown in Fig. 5, the amount of deformation of the first member 11 after the bonding step S2 due to heating is measured from the side opposite to the side where the second member 21 is located.

[0050] Specifically, the surface 11a of the first member 11 is irradiated with laser light while a measurement sensor 70 that irradiates laser light is moved between one restraining member 40 and the other restraining member 40, and the surface shape (surface roughness) of the first member 11 is measured (measurement of the surface shape after heating). Note that, although the surface shape is measured by irradiating laser light, the measurement method is not particularly limited as long as it is possible to measure the surface shape.

[0051] Next, the amount of deformation of the first member 11 due to heating during the bonding step S2 is calculated based on the surface shape of the first member 11 before heating the mastic adhesive 30. In detail, the amount of deformation of the first member 11 due to heating during the bonding step S2 is calculated by subtracting the measurement value obtained from the measurement of the surface shape before heating from the measurement value obtained from the measurement of the surface shape after heating.

[0052] An example of the calculation results relating to the amount of deformation of the first member 11 is shown in Figures 6(a) to 6(e). In the graphs of Figures 6(a) to 6(e), the surface shape of the first member 11 before heating the mastic adhesive 30 is shown as a line indicating no deformation. The amount of deformation of positive deformation and the amount of deformation of negative deformation are shown on the plus and minus sides of the Y-axis, respectively.

[0053] As shown in Fig. 4(c) and Fig. 5, when the deformation of the first member 11 after heating has both positive and negative deformation, the calculated curve showing the deformation amount of the first member 11 becomes a wavy curve having both convex and concave shapes with respect to a line of no deformation, as shown in Fig. 6(a). That is, the deformation of the first member 11 as shown in Fig. 6(a) is an example of the deformation shown in (1) in the present invention.

[0054] On the other hand, when the deformation of the first member 11 after heating is only positive deformation, the calculated curve of the deformation amount of the first member 11 is a convex curve with respect to the no-deformation line, as shown in Fig. 6(b). When the deformation of the first member 11 after heating is only negative deformation, the calculated curve of the deformation amount of the first member 11 is a concave curve with respect to the no-deformation line, as shown in Fig. 6(c).

[0055] In addition, as shown in FIG. 6(d), the first member 11 may be deformed so that the entire first member 11 has a convex shape, and the first member 11 is partially concave with respect to the entire convex shape of the first member 11. Specifically, the curve of the deformation amount of the first member 11 is a curve located on the positive side of the no-deformation line, and includes a curve that is partially concave toward the no-deformation line. That is, the deformation of the first member 11 as shown in FIG. 6(d) is an example of the deformation shown in (2) in the present invention. Note that the deformation shown in FIG. 6(d) is a deformation in which the center part of the first member 11 is partially concave, but for example, the first member 11 may be partially concave at multiple places.

[0056] In addition, as shown in FIG. 6(e), the first member 11 may be deformed in such a way that the entire first member 11 is negatively deformed to have a concave shape, and the first member 11 is partially deformed relative to the overall concave shape of the first member 11. Specifically, the curve of the deformation amount of the first member 11 is a curve located on the negative side of the no-deformation line, and includes a curve that is partially deformed toward the no-deformation line. That is, the deformation of the first member 11 as shown in FIG. 6(e) is an example of the deformation shown in (3) in the present invention. Note that the deformation shown in FIG. 6(e) is a deformation in which the central part of the first member 11 is partially deformed, but the first member 11 may be partially deformed at multiple points, for example.

[0057] 2-4. Judgment process S4 Next, a judgment step S4 is performed. In this step, if the measured deformation of the first member 11 includes both positive deformation and negative deformation, it is judged that the combination of the outer panel corresponding to the first member 11 and the mastic adhesive 30 is inappropriate.

[0058] Specifically, when the deformation of the first member 11 after heating has both positive and negative deformations, as shown in FIG. 6(a), the curve pattern showing the deformation amount of the first member 11 is a wavy line having both convex and concave curves with respect to the line without deformation. When the deformation of the first member 11 after heating has both positive and negative deformations, as shown in FIG. 6(d), the first member 11 is positively deformed so that the entire first member 11 has a convex shape and is partially deformed so that the entire first member 11 is ...

[0059] In these deformations, incident light is specularly reflected by locally bulging convex portions 11f (i.e., positively deformed portions) and is prone to diffuse reflection by concave portions 11g (i.e., negatively deformed portions), and the difference in intensity of the reflected light can impair the design of the exterior plate (see FIG. 7). Therefore, it is determined that the combination of the exterior plate corresponding to the first member 11 and the mastic adhesive 30 is inappropriate.

[0060] On the other hand, when the curve pattern showing the amount of deformation of the first member 11 is either convex or concave with respect to the line showing no deformation as shown in Figures 6(b) and 6(c), the deformation of the first member 11 after heating is either positive or negative, as described above. In this case, the deformation is difficult to recognize because the incident light is diffusely reflected by the entire exterior plate. Therefore, in this case, it can be considered that the design of the exterior plate is not impaired by this deformation, and therefore the combination of the exterior plate corresponding to the first member 11 and the mastic adhesive 30 is determined to be appropriate.

[0061] If the combination is judged to be inappropriate, the above-mentioned bonding step S2, measuring step S3, and judging step S4 may be repeated using a test specimen 10 with a different thickness and material of the first member 11, a different type of mastic adhesive 30, and different heating conditions, until the combination is judged to be appropriate. When changing the mastic adhesive 30, the curing start temperature and curing time may be adjusted by changing the amount and type of curing agent added. If the mastic adhesive 30 contains a foaming agent, the amount of foaming agent added may be adjusted.

[0062] This makes it possible to obtain an appropriate combination of the outer panel and the mastic adhesive 30 on an actual automobile production line. For example, on an automobile production line, it may be difficult to change the heating conditions of the paint baking oven in each factory, or it may be difficult to change the thickness of the outer panel after the vehicle design has been decided. Even in such cases, since the test specimen 10 simulating the vehicle can be used, it is possible to obtain an appropriate combination of the outer panel and the mastic adhesive 30 according to the heating conditions of the paint baking oven and the decided thickness of the outer panel.

[0063] According to this embodiment, the first and second members 11, 21 are arranged so as to sandwich the mastic adhesive 30, and the first and second members 11, 21 are restrained by a pair of restraining members 40, 40 so that the mastic adhesive 30 is arranged between the pair of restraining members 40, 40. This makes it possible to simulate a state in which the outer panel of a vehicle and a reinforcing member are arranged so as to sandwich the mastic adhesive 30, and both ends are restrained. In this state, the mastic adhesive 30 is heated to bond the mastic adhesive 30. Next, after bonding (i.e., after heating), the amount of deformation of the first member 11 deformed by heating is measured. This makes it possible to simulate the deformation that actually occurs in the outer panel of a vehicle due to the mastic adhesive 30, and to measure the amount of deformation.

[0064] As described above, among the deformations caused by heating, the deformations shown in Fig. 6(a), Fig. 6(d), and Fig. 6(e) may cause the design of the outer panel of an actual vehicle to be impaired. Therefore, when the deformation of the first member 11 after heating includes both positive and negative deformations, it is determined that the outer panel and the mastic adhesive 30 are an inappropriate combination. Similarly, when the deformation is a positive deformation in which the entire first member 11 has a convex shape and the deformation is a deformation that is partially concave with respect to the entire convex shape of the first member 11, it is determined that the outer panel and the mastic adhesive 30 are an inappropriate combination. Furthermore, similarly, when the deformation is a negative deformation in which the entire first member 11 has a concave shape and the deformation is a deformation that is partially bulging with respect to the entire concave shape of the first member 11, it is also determined that the outer panel and the mastic adhesive 30 are an inappropriate combination.

[0065] This makes it possible to determine inappropriate combinations of the exterior panel and the mastic adhesive 30 that would cause deformation that would impair the design when the exterior panel and the reinforcing member of a vehicle are bonded together via the mastic adhesive 30. As a result, it is possible to eliminate such inappropriate combinations, and therefore it is possible to actually prevent the occurrence of deformation that would impair the design when the exterior panel and the reinforcing member are bonded together via the mastic adhesive 30. EXAMPLES

[0066] The present invention will now be described with reference to examples.

[0067] 1. Temperature rise and thermal expansion of the first and second components Test specimens according to Reference Examples 1 and 2 were prepared, and the test specimens were placed in a drying furnace. While the test specimens were being heated, the temperatures of the first and second members were measured. In addition, the behavior of the first and second members during heating was observed. This will be described in detail below.

[0068] <Reference example 1> As Reference Example 1, a test specimen was prepared in which uncured mastic adhesive was placed, as shown in Fig. 2. The test specimen used a steel plate with a thickness of 0.6 mm as the first member and a steel plate with a thickness of 1.6 mm as the second member. In addition, an adhesive with synthetic rubber as the main component was used as the mastic adhesive.

[0069] The heating conditions in the drying oven were as follows: the temperature was raised from 16°C to 170°C in 3.5 minutes, the temperature was maintained for a certain period of time after the temperature was raised, and then the temperature was lowered (rapid temperature rise conditions). In order to prevent uneven temperature distribution, shielding plates were placed around the specimen.

[0070] The temperatures of the first and second members were measured at predetermined time intervals after the test specimens were placed in the drying oven by placing a thermocouple near the center of the mastic adhesive dot-applied in the center of the surface of the main body of the second member. In addition, the behavior of the first and second members was observed immediately after they were placed in the drying oven and after a predetermined time had passed since they were placed in the drying oven.

[0071] <Reference example 2> The temperatures of the first and second members of Reference Example 2 were measured in the same manner as Reference Example 1, except that the plate thickness of the first member was 0.8 mm.

[0072] (Results / Discussion) The results are shown in Fig. 8. Fig. 8 is a graph showing the relationship between the temperature and the elapsed time after the first and second members according to Reference Examples 1 and 2 were placed in a drying oven. In the graph, the solid line indicates the second members of Reference Examples 1 and 2, the dashed and dotted line indicates the first member of Reference Example 1, and the dotted line indicates the first member of Reference Example 2.

[0073] As can be seen from FIG. 8, in both Reference Examples 1 and 2, the temperature of the first member rose before the second member immediately after being placed in the drying oven, and as time passed, the first and second members approached the same temperature. In other words, it can be seen that the first member stretches before the second member due to heating. This means that when the first and second members are made of the same material, such as steel, the second member has a large heat capacity because it serves as a reinforcing material, and it takes time for it to rise to the same temperature as the first member. In other words, the first member is more likely to stretch due to thermal expansion than the second member, so the first member is more likely to deform due to the heat of the bonding process.

[0074] 2. How to judge the combination of exterior panels and mastic adhesive 30 Using the test specimen shown in Figure 2, the above-mentioned evaluation method was carried out while changing the plate thickness of the first member, the type of mastic adhesive, and the heating conditions. The details are described below.

[0075] <Test specimen 1> A steel plate with a thickness of 0.8 mm was prepared as the first member, and a steel plate with a thickness of 1.6 mm was prepared as the second member. Next, a single dot of uncured mastic adhesive (diameter 15 mm x thickness 4 mm) was applied to the center of the surface of the main body of the second member. A rubber-based adhesive (material A) was used as the mastic adhesive. After dot application, the gap (clearance) between the first and second members was adjusted to 3 mm with a washer, and the first member was placed on top of them so that the back surface of the first member was in contact with the mastic adhesive and the surface of the washer. Both sides of the first and second members were fixed with bolts and nuts to prepare a test specimen 1 in which uncured mastic adhesive was placed.

[0076] <Test specimens 2-4> Specimens 2 to 4 were prepared in the same manner as specimen 1. Specimen 2 differs from specimen 1 in that an adhesive (material B) with different hardening characteristics of the mastic adhesive was used. Specimen 3 differs from specimen 1 in that the steel plate of the first member has a thickness of 0.6 mm. Specimen 4 differs from specimen 1 in that an adhesive (material B) with different hardening characteristics of the mastic adhesive was used, and that the steel plate of the first member has a thickness of 0.6 mm.

[0077] The surface of the first member of the prepared specimens 1 to 4 was irradiated with laser light, and the surface shape of the first member (surface shape before heating) was measured from one restraining member to the other restraining member. The surface shape measurement conditions are as follows.

[0078] (Surface shape measurement conditions) Measuring instrument: High-precision shape measuring system K2-300 (manufactured by Kozu Seiki) Measurement sensor: CCD laser displacement meter LKG-30 (Keyence) Measurement position: Center line of the short side of the first component steel plate (measurement distance: 240 mm) Measurement temperature: 23℃ Measurement pitch: 0.1mm Measurement speed: 40mm / sec

[0079] Next, the test pieces 1 to 4 were placed in a drying oven, and the mastic adhesive was heated under the above-mentioned rapid temperature rise conditions to cure the uncured mastic adhesive and foam the foaming agent, thereby bonding the first and second members. Similarly, other test pieces 1 to 4 were placed in a drying oven, and the mastic adhesive was heated under the following slow temperature rise conditions to cure the uncured mastic adhesive and foam the foaming agent, thereby bonding the first and second members. In the slow temperature rise, the temperature was raised from 20°C to 170°C in 19.5 minutes, and after the temperature rise, the temperature was held for a certain period of time, and then the temperature was lowered.

[0080] Next, in the same manner as in the measurement of the surface shape before heating described above, the surface shapes of the first members of specimens 1 to 4 in the state in which the first and second members were bonded (surface shapes after heating) were measured. The deformation amounts of the first members after heating for specimens 1 to 4 were calculated by subtracting the measured values ​​of the surface shapes before heating described above from the measured values ​​of the surface shapes after heating obtained. These results are shown in FIG. 9. In the graph of FIG. 9, the deformation amounts (strain amounts) of the first member in the direction away from the second member and in the direction toward the second member are shown as positive and negative sides, respectively.

[0081] (Results / Discussion) As can be seen from the results in Figure 9, when test piece 4 was bonded with a slow temperature rise (see the graph at the bottom right), the surface shape was wavy and had both positive and negative deformation, but in other cases, the deformation was only either positive or negative.

[0082] From these results, for example, when the outer plate, reinforcing material, and mastic adhesive corresponding to the test piece 4 were selected and heated under a slow temperature rise condition, positive and negative deformation occurred, and the design of the outer plate was impaired, as shown in FIG. 7. Therefore, in this case, it was possible to determine that the mastic adhesive and the outer plate were not appropriate. In other cases, only positive or negative deformation occurred, so the design of the outer plate was ensured, and it was possible to determine that the mastic adhesive and the outer plate (thickness) were appropriate. Furthermore, from the results of test pieces 1 to 4, it was possible to grasp the tendency of the design of the outer plate of an actual vehicle. Note that, since it is difficult to change the temperature rise conditions of the drying oven in an actual production line, the appropriateness of deformation is determined from the combination of the mastic adhesive and the outer plate.

[0083] Furthermore, if the combination is determined to be inappropriate, the plate thickness of the first component of the test specimen, the type of mastic adhesive, and the heating conditions can be changed and the evaluation can be continued, ultimately resulting in a combination of exterior panel and mastic adhesive that can be used on an actual production line.

[0084] Although one embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various design modifications can be made without departing from the spirit of the present invention described in the claims.

[0085] For example, in the above embodiment, the surface shape of the first member before and after heating is measured, and the positive and negative deformations are determined based on the surface shape of the first member before heating. However, the positive and negative deformations may be determined by measuring only the surface shape of the first member after heating. In this case, the surface shape of the first member near where the restraining member is disposed is unlikely to deform before and after heating due to the restraint, so the positive and negative deformations may be determined based on this surface shape. [Explanation of symbols]

[0086] 100: vehicle, 101: roof panel, 102: reinforcement, 11: first member, 21: second member, 30: mastic adhesive, 40: restraining member, S1: preparation step, S2: adhesion step, S3: measurement step, S4: evaluation step

Claims

[Claim 1] A preparation process of preparing a first member assumed to be an outer panel of a vehicle and a second member assumed to be a reinforcing member for reinforcing the outer panel; a bonding process in which the first member and the second member are arranged so as to sandwich a mastic adhesive therebetween, the first member and the second member are restrained by at least two restraining members so that the mastic adhesive is arranged between the at least two restraining members, and the first member and the second member are bonded together by heating the mastic adhesive; a measuring step of measuring an amount of deformation of the first member caused by heating during the bonding step from an opposite side to a side on which the second member is located with respect to the first member after the bonding step; a determination step of determining that the combination of the exterior panel corresponding to the first member and the mastic adhesive is inappropriate if the measurement step includes any one of the following deformations (1) to (3) when, in the deformation of the first member after heating during the bonding process, a deformation in a direction away from the second member is defined as positive deformation and a deformation in a direction toward the second member is defined as negative deformation relative to the first member before heating during the bonding process. (1) The deformation of the first member includes both the positive deformation and the negative deformation. (2) The positive deformation is such that the first member as a whole has a convex shape, and the first member is partially concave with respect to the overall convex shape. (3) The negative deformation is such that the first member has a concave shape as a whole, and is a deformation in which the first member partially bulges out relative to the overall concave shape.

Images