Mastic distortion prediction method

Abstract

To provide a mastic distortion prediction method for accurately predicting distortion of an outer plate panel caused by a mastic adhesive.SOLUTION: A mastic distortion prediction method includes the steps of: measuring an inter-face displacement amount before and after coating and baking for each coating amount of a mastic adhesive 11 while changing the coating amount; performing coating and baking for each of the coating amounts while changing the coating amount of the mastic adhesive 11, and then measuring a maximum displacement amount of the mastic adhesive 11 in a state in which a clip 15 for fixation and an inter-face jig 12 are removed; and predicting, by CAE simulation, mastic distortion of the outer plate panel when coating the mastic adhesive 11 between an actual outer plate panel and a reinforcement member and performing coating and baking, on the basis of the maximum displacement amount and a three-dimensional model of the outer plate panel and the reinforcement member.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for predicting distortion (displacement) of an exterior panel caused by a mastic adhesive. [Background technology]

[0002] Mastic adhesives are adhesives that contain thermosetting materials such as thermosetting resins and thermosetting rubbers, and are used, for example, as adhesives to bond exterior panels such as the hood, doors, and roof of an automobile to reinforcing members that reinforce the exterior panels.

[0003] On the other hand, mastic adhesives foam and expand when heated, and then shrink when cooled, and this change in volume can cause distortion (bulges, dents, etc.) in the bonded parts of the exterior panels. In particular, in recent years, there has been a demand to make parts such as exterior panels thinner in order to reduce costs and weight, and using thinner parts makes it easier for distortion to occur in the bonded parts.

[0004] Therefore, if it were possible to predict in advance (before the actual bonding) the distortion of exterior panels caused by mastic adhesive, it would be possible to determine whether a product was good or bad before production, and it would also be possible to significantly reduce the labor hours and costs required to select components, such as the material and thickness of the exterior panels and the type of mastic adhesive.

[0005] For example, Patent Document 1 listed below discloses a distortion determination method that can predict distortion of an adherend caused by a mastic adhesive with few steps and at low cost.

[0006] Specifically, the following steps are carried out: heating and cooling the mastic adhesive to a predetermined temperature and calculating the thermal expansion coefficient of the mastic adhesive; applying the mastic adhesive to an adherend and calculating the shape of the adherend when it is heated and cooled to the predetermined temperature as three-dimensional data by CAE simulation based on the thermal expansion coefficient of the mastic adhesive and a three-dimensional model of the adherend; and analyzing the curvature of the adherend based on the three-dimensional data calculated by CAE simulation to determine the strain strength, which is a numerical value representing the magnitude of strain in the adherend. Through these steps, the strain of the adherend that will occur when the mastic adhesive is applied to the adherend and heated and cooled to the predetermined temperature is predicted. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2019-59887 A Summary of the Invention [Problem to be solved by the invention]

[0008] As described above, in the method described in Patent Document 1, the thermal expansion coefficient of the mastic adhesive is calculated, and the shape of the adherend when heated and cooled is calculated as three-dimensional data using the thermal expansion coefficient, thereby determining the distortion of the adherend. The thermal expansion coefficient of the mastic adhesive is calculated from the temperature change and the volume change of the mastic adhesive by heating and cooling the mastic adhesive using a viscoelasticity tester (shear test), and is 0.05×10 -3 / ℃·m or more 1.5×10 -3 / ℃·m or less.

[0009] On the other hand, the actual distortion of the exterior panel caused by the mastic adhesive includes distortion in the bulging direction and distortion in the concave direction.

[0010] However, the method described in the above-mentioned cited document 1 uses the thermal expansion coefficient, i.e., predicts the distortion of the adherend (outer panel) caused by the mastic adhesive by considering only the expansion direction, which has the disadvantage that the prediction accuracy of distortion in the concave direction, which occurs relatively frequently, is low.

[0011] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a mastic distortion prediction method for accurately predicting the expanding and contracting distortions of an exterior panel caused by mastic adhesive. [Means for solving the problem]

[0012] The mastic distortion prediction method of the present invention is characterized by carrying out the following steps in order to predict the mastic distortion of an exterior panel that occurs when a mastic adhesive that bonds an exterior panel to a reinforcing member that reinforces the exterior panel is heated and cooled by painting and baking.

[0013] First, a first plate member that is sufficiently thinner than the actual exterior panel and a second plate member representing the reinforcing member are arranged so as to sandwich the mastic adhesive and a surface-to-surface jig of a predetermined height arranged on both ends of the first plate member and the second plate member, and a test device is prepared in which the movement of each plate member is restrained by clamping both ends of the first plate member and the second plate member together with the surface-to-surface jig with fixing clips.A surface-to-surface displacement measurement process is then performed in which the amount of mastic adhesive applied is changed and the surface-to-surface displacement amount, which is the amount of displacement in the surface-to-surface distance before and after painting and baking, is measured for each amount of application, and the displacement tendency of the mastic adhesive due to expansion or contraction is determined.

[0014] Next, a third plate member representing an actual exterior panel and a second plate member representing the reinforcing member are arranged so as to sandwich the mastic adhesive and the inter-face jigs arranged on both ends of the mastic adhesive, and a test device is prepared in which the movement of each plate member is restrained by clamping both ends of the third plate member and the second plate member together with the inter-face jigs with fixing clips.Then, while changing the amount of mastic adhesive applied, paint baking is performed for each amount of application, and then a maximum displacement measurement process is performed in which the maximum displacement of the mastic adhesive is measured with the fixing clips and the inter-face jigs removed.

[0015] Finally, a mastic distortion prediction process is performed in which the mastic distortion of the exterior panel when the mastic adhesive is applied between the exterior panel and the reinforcing member and painting and baking are performed is predicted by CAE simulation based on the maximum displacement amount and a three-dimensional model of the exterior panel and the reinforcing member.

[0016] In this way, by implementing the mastic distortion prediction method of the present invention, it is possible to accurately predict the expanding and collapsing distortions of an exterior panel caused by the mastic adhesive.

[0017] Furthermore, in the mastic distortion prediction method according to the present invention, it is preferable to convert the maximum displacement amount into a coefficient in advance by mathematically formulating the amount of mastic applied per unit area of ​​the exterior panel, and to use the converted coefficient in predicting the mastic distortion by CAE simulation. Effect of the Invention

[0018] According to the mastic distortion prediction method of the present invention, it is possible to accurately predict the distortion in the expanding direction and the distortion in the concave direction of an exterior panel caused by a mastic adhesive. [Brief description of the drawings]

[0019] [Figure 1]FIG. 1 is a schematic diagram showing the configuration of a testing device used in the method for predicting mastic distortion according to the present invention. [Diagram 2] FIG. 2 is a flowchart showing an example of a method for predicting mastic distortion according to the present invention. [Diagram 3] FIG. 3 is a flowchart showing a procedure for measuring the inter-surface displacement amount. [Figure 4] FIG. 4 is a flowchart showing a procedure for measuring the maximum displacement amount. [Diagram 5] FIG. 5 is a schematic diagram showing an example of a process for measuring the maximum displacement amount. [Figure 6] FIG. 6 is a diagram showing the measurement results of the inter-surface displacement amount. [Figure 7] FIG. 7 is a diagram showing the measurement results of the maximum displacement of the mastic adhesive. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the mastic distortion prediction method according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to this embodiment. In addition, in the specification and drawings of the present application, elements that can be similarly explained may be given the same reference numerals to avoid duplicate explanations.

[0021] An embodiment of a method for predicting mastic distortion according to the present invention will be described in detail with reference to Figures 1 to 4. Hereinafter, a roof panel, a hood panel, a front fender panel, a side panel, a door panel, a back door panel, etc. are assumed as examples of exterior panels.

[0022] <Vehicle configuration> A vehicle has a body made of metal steel plates, and the body is composed of body panel structures such as a hood, a trunk lid, doors, sides, and a roof. The body defines a passenger compartment surrounded by these body panel structures. The body panel structures are assembled, for example, in an automobile production line, by bonding an outer panel and a reinforcing member that reinforces the outer panel with a mastic adhesive. The mastic adhesive is applied to the outer panel and the reinforcing member in the automobile production line, and cured, for example, by heating in a paint baking oven.

[0023] However, when an outer panel and a reinforcing member are bonded together using a mastic adhesive, deformation of the bonded portion of the outer panel may occur due to the mastic adhesive. In particular, in recent years, there has been a demand for thinner members such as outer panels in order to reduce costs and weight, and when thinner members are used, distortion is more likely to occur in the bonded portion.

[0024] Therefore, in the mastic distortion prediction method of the present embodiment, distortion of an exterior panel caused by mastic adhesive is predicted before assembly on an automobile manufacturing line, and, for example, the material and thickness of the exterior panel and the type of mastic adhesive are adjusted in advance so that the distortion of the exterior panel during assembly falls within an allowable range, thereby significantly reducing the number of work steps and costs during assembly.

[0025] <Test Equipment> Before describing the mastic distortion prediction method of the present embodiment, a test device for predicting distortion of an exterior panel caused by a mastic adhesive will be described.

[0026] 1 is a schematic diagram showing the configuration of a testing device used in the method for predicting mastic distortion of the present embodiment. For convenience of explanation, the top, bottom, left, and right in the figure may be referred to as "upper," "lower," "left," and "right" hereinafter.

[0027] The testing apparatus 1 used in this embodiment comprises a mastic adhesive 11, a first plate member 13 and a second plate member 14 of approximately identical shape arranged one above the other so as to sandwich the mastic adhesive 11 and two inter-face jigs 12 located on either side of it, and two fixing clips 15 that clamp the ends of the first plate member 13 and the second plate member 14 together with the inter-face jigs 12.

[0028] The mastic adhesive 11 is applied so as to come into contact with both the first plate member 13 and the second plate member 14, and the unhardened mastic adhesive 11 in contact with the first plate member 13 and the second plate member 14 is hardened by heating, thereby bonding the first plate member 13 and the second plate member 14 together.

[0029] The mastic adhesive 11 has a thermosetting material and a foaming agent that imparts flexibility, and the thermosetting material can be, for example, a thermosetting resin or a thermosetting rubber, and the foaming agent can be, for example, an organic foaming agent or an inorganic foaming agent. Furthermore, the mastic adhesive 11 may contain a filler, a crosslinking agent, a softener, etc., as necessary.

[0030] The first plate member 13 is a flat plate member that corresponds to an outer panel of a vehicle, and examples of materials include aluminum, aluminum alloys, alloys such as steel, and fiber reinforced plastics (FRP) such as carbon fiber reinforced plastics.

[0031] The second plate member 14 is a flat plate member corresponding to the reinforcing member that reinforces the outer panel, and is preferably made of the same material as the actual reinforcing member, such as an alloy such as steel. The thickness of the second plate member 14 is preferably such that it does not deform due to the expansion and contraction of the mastic adhesive 11, and is particularly preferably the same as the thickness of the actual reinforcing member, for example.

[0032] The first plate member 13 and the second plate member 14 used in this embodiment have substantially the same shape, but there is no particular limitation on the shape as long as they can be clamped together with the inter-face jig 12 by the fixing clip 15. The material of the inter-face jig 12 used in this embodiment is also not particularly limited as long as it is a material that does not deform when heated, and for example, a material that can constantly maintain the gap (inter-face distance) between the first plate member 13 and the second plate member 14 at about 5 mm is used.

[0033] The fixing clip 15 restrains the movement of each plate member with the inter-face jig 12 sandwiched between the first plate member 13 and the second plate member 14. The fixing clip 15 used in this embodiment is not limited to a clip-shaped one as long as it can sufficiently restrain the movement of each plate member. For example, the first plate member 13, the inter-face jig 12, and the second plate member 14 may be stacked in this order to form a through hole, and bolts and nuts may be used as restraining members to restrain the movement of each member.

[0034] <Mastic distortion prediction method> Next, the method for predicting mastic distortion of this embodiment will be described in detail with reference to the drawings. Fig. 2 is a flowchart showing an example of the method for predicting mastic distortion of this embodiment.

[0035] <Measurement of interfacial displacement and displacement tendency> In the method for predicting mastic distortion of this embodiment, first, a test apparatus 1 shown in FIG. 1 is prepared, and the amount of mastic adhesive 11 applied per unit area (g / cm 2 ), the amount of displacement (mm) between the surfaces before and after painting and baking is measured for each application amount, and the expansion or contraction displacement tendency (mastic properties) of the mastic adhesive 11 is determined (Step S1). In this step, the displacement tendency and amount of displacement of the mastic adhesive 11 can be accurately grasped, so that measures can be taken in advance in the maximum displacement measurement process described below, and the accuracy of the CAE simulation can be verified.

[0036] In this embodiment, as an example, the amount of the mastic adhesive 11 applied is 1.5 g / cm 2 , 2.0g / cm 2 , 2.5g / cm 2 In the above cases, the interfacial displacement amount is measured for each application amount, and the displacement tendency (expansion, contraction) of the mastic adhesive 11 is judged. 2 , 2.0g / cm 2 , 2.5g / cm 2 ) and the number of times the inter-surface displacement is measured (three times in this embodiment) are not limited to these and can be set appropriately depending on the required accuracy of mastic distortion prediction and temperature conditions (heating, cooling), etc.

[0037] Specifically, the inter-surface displacement amount is measured for each applied amount of the mastic adhesive 11 as follows (Step S1: inter-surface displacement amount measuring step). Fig. 3 is a flowchart showing the procedure for measuring the inter-surface displacement amount.

[0038] In the interfacial displacement measurement process, first, a first plate member 13 that is sufficiently thinner than an actual exterior panel, i.e., that is easy to obtain mastic properties (expansion, contraction), is prepared (step S1-1). Here, as the first plate member 13, for example, a steel plate (10×10=100 cm 2 ) is used. Furthermore, in the inter-surface displacement measurement process, a second plate member 14 is prepared to simulate a reinforcing member for reinforcing the outer panel (step S1-1). The second plate member 14 may have a thickness and strength that does not deform before and after painting and baking. For example, a steel plate with a thickness of 1.6 mm (10×10=100 cm), which is approximately the same as the thickness of the actual reinforcing member, is used. 2 In addition, each plate member may have substantially the same shape, and the size (cm 2 ) can be appropriately set depending on the required accuracy of mastic distortion prediction and temperature conditions (heating, cooling), etc.

[0039] Then, in the interfacial displacement measurement process, the applied 1.5 g / cm 2The first plate member 13 and the second plate member 14 are arranged so as to sandwich the mastic adhesive 11 and the inter-face jigs 12 with a height of about 5 mm arranged on both ends, and the movement of each plate member is restricted by sandwiching both ends of the first plate member 13 and the second plate member 14 together with the inter-face jigs 12 with fixing clips 15 (step S1-2: see FIG. 1). At this time, the mastic adhesive 11 is applied near the center of each plate member so as to contact both the first plate member 13 and the second plate member 14. Furthermore, the inter-face distance at this point (before painting and baking) is 5 mm, which is the height of the inter-face jig 12. The height of the inter-face jig 12 can be adjusted appropriately according to the expected magnitude of expansion and contraction of the mastic adhesive 11.

[0040] In this state, in the inter-surface displacement measurement process, the test device 1 is painted and baked in a drying furnace, and the mastic adhesive 11 is heated and cooled under predetermined temperature conditions to bond the first plate member 13 and the second plate member 14 (step S1-3). At this time, the mastic adhesive 11 is heated so that the foaming agent contained therein foams and the uncured resin hardens. Then, the mastic adhesive 11 that has completed foaming and hardening is appropriately cooled.

[0041] The temperature conditions for heating and cooling the mastic adhesive 11 are set appropriately according to its type, i.e., according to the temperature characteristics for hardening and foaming. Specifically, 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 set appropriately as temperature conditions.

[0042] In detail, the heating temperature is, for example, preferably 140° C. or more and 220° C. or less, more preferably 160° C. or more and 200° C. or less, and most preferably 170° C. or more and 190° C. or less. In addition, the heating rate is preferably, for example, 30° C. / min. or more and 50° C. / min. or less when the temperature is raised rapidly, while it is preferably, for example, 3° C. / min. or more and 20° C. / min. or less when the temperature is raised slowly. In addition, the time for which the heating temperature is maintained is preferably, for example, 5 minutes or more and 40 minutes or less.

[0043] The cooling temperature is preferably, for example, 60° C. or less. The cooling rate is preferably, for example, 5° C. / min to 30° C. / min. After cooling, the test apparatus 1 is preferably left to cool to a temperature at which the inter-surface displacement can be measured (for example, room temperature).

[0044] In the inter-surface displacement measurement process, the test device 1 after the paint baking is used to measure the inter-surface distance (mm) between the first plate member 13 and the second plate member 14, and the difference between the inter-surface distance (5 mm) before the paint baking and the inter-surface distance after the paint baking is calculated as the inter-surface displacement (step S1-4). This allows the mastic properties (expansion, contraction) to be obtained. The inter-surface displacement calculated here is the displacement of the first plate member 13 corresponding to the amount of mastic adhesive 11 applied (the second plate member 14 does not displace), and if the first plate member 13 is distorted in the expanding direction, the value is "+", and if it is distorted in the concave direction, the value is "-".

[0045] Thereafter, the amount of the mastic adhesive 11 applied was set to 2.0 g / cm 2 , 2.5g / cm 2 The inter-surface displacement amounts in the above cases are also measured in the same manner.

[0046] <Measurement of maximum displacement> In the method for predicting mastic distortion according to the present embodiment, after measuring the amount of inter-surface displacement in the inter-surface displacement measurement step described above, a test apparatus 1 is prepared in which the first plate member 13 is changed to a plate member having the same thickness as that of the outer panel to be actually adopted, and the application amount (g / cm) of the mastic adhesive 11 per unit area is measured. 2 After that, the fixing clip 15 and the inter-face jig 12 are removed and the maximum displacement (mm) of the mastic adhesive 11 is measured (step S2). In this embodiment, as an example, the application amount of the mastic adhesive 11 is 1.5 g / cm 2 , 2.0g / cm 2 , 2.5g / cm 2 The maximum displacement is measured for each of the cases. 2 , 2.0g / cm 2 , 2.5g / cm 2 ) and the number of times the maximum displacement is measured (three times in this embodiment) are not limited to these and can be set appropriately depending on the required accuracy of mastic distortion prediction and temperature conditions (heating, cooling), etc.

[0047] Specifically, the maximum displacement of the mastic adhesive 11 is measured for each application amount as follows (Step S2: maximum displacement measurement step). Fig. 4 is a flow chart showing the procedure for measuring the maximum displacement.

[0048] In the maximum displacement measurement process, first, a first plate member 13 having the same material and thickness as the outer panel to be actually adopted is prepared (step S2-1). Here, as the first plate member 13, for example, a steel plate having a thickness of 0.6 mm (10×10=100 cm 2 ) is used. Furthermore, in the maximum displacement measurement step, a second plate member 14 is prepared to simulate a reinforcing member for reinforcing the outer panel (step S2-1). As in the inter-surface displacement measurement step, the second plate member 14 only needs to have a thickness and strength that does not deform before and after painting and baking. For example, a steel plate with a thickness of 1.6 mm (10×10=100 cm), which is approximately the same as the thickness of the actual reinforcing member, is used. 2In addition, each plate member may have substantially the same shape, and the size (cm 2 ) can be appropriately set depending on the required accuracy of mastic distortion prediction and temperature conditions (heating, cooling), etc.

[0049] Thereafter, in the maximum displacement measurement step, the applied 1.5 g / cm 2 The first plate member 13 and the second plate member 14 are arranged so as to sandwich the mastic adhesive 11 and the inter-face jigs 12 with a height of about 5 mm arranged on both ends, and the movement of each plate member is restrained by sandwiching both ends of the first plate member 13 and the second plate member 14 together with the inter-face jigs 12 with fixing clips 15 (step S2-2: see FIG. 1). At this time, the mastic adhesive 11 is applied near the center of each plate member so as to contact both the first plate member 13 and the second plate member 14. In addition, the displacement amount of the first plate member 13 at this point (before painting and baking) is set to 0 (5 mm, which is the height of the inter-face jig 12, is set as the reference value). The height (mm) of the inter-face jig 12 can be appropriately adjusted according to the expected magnitude of expansion and contraction of the mastic adhesive 11.

[0050] In this state, in the maximum displacement measurement step, similarly to step S1-3 above, the test apparatus 1 is painted and baked in a drying furnace, and the mastic adhesive 11 is heated and cooled to bond the first plate member 13 and the second plate member 14 (step S2-3). Note that the temperature conditions for heating and cooling the mastic adhesive 11 are similar to those in step S1-3 above.

[0051] Thereafter, in the maximum displacement measurement process, the fixing clip 15 and the inter-face jig 12 are removed from the test apparatus 1 after the paint has been baked (step S2-4: see FIG. 5). At this time, if the mastic adhesive 11 has mastic properties that cause it to expand when the paint is baked, it will deform in an expanding direction, whereas if it has mastic properties that cause it to shrink when the paint is baked, it will deform in a contracting direction. Then, in the maximum displacement measurement process, the displacement of the mastic adhesive 11 (displacement from the reference value of 5 mm) is measured with the fixing clip 15 and the inter-face jig 12 removed (step S2-5: see FIG. 5). Note that the displacement measured with the fixing clip 15 and the inter-face jig 12 removed is based on this applied amount (1.5 g / cm 2 ) (hereinafter referred to as maximum displacement) of the mastic adhesive 11. The maximum displacement measured here is a "+" value (mm) when the mastic adhesive 11 is deformed in the expanding direction, and a "-" value (mm) when the mastic adhesive 11 is deformed in the contracting direction.

[0052] Then, the coating amount was 2.0 g / cm 2 , 2.5g / cm 2 The maximum displacement of the mastic adhesive 11 in each of the above cases is also measured in the same manner.

[0053] <Prediction of mastic distortion (displacement)> After measuring the maximum displacement of the mastic adhesive 11 in the maximum displacement measurement process described above, in the mastic distortion prediction method of this embodiment, the mastic distortion (displacement) of the exterior panel caused by the mastic adhesive 11 is calculated as three-dimensional data by CAE simulation (step S3: mastic distortion prediction process).

[0054] Here, in the mastic distortion prediction step, as a prerequisite process prior to the CAE simulation, the maximum displacement measured in the maximum displacement measurement step is converted in advance into a displacement coefficient (a coefficient representing the displacement of the mastic adhesive 11) by a predetermined method. This displacement coefficient is a coefficient that changes depending on the type of mastic adhesive 11, the inter-face distance, and the material and thickness of the exterior panel, and is calculated, for example, by mathematically formulating the relationship between the maximum displacement and the amount of mastic applied per unit area of ​​the exterior panel.

[0055] In this embodiment, the process of converting the maximum displacement amount into a displacement coefficient is described as a prerequisite process in the mastic distortion prediction process, but this is not limited to this, and this process may also be performed in the maximum displacement amount measurement process described above.

[0056] Based on the above, in the mastic distortion prediction step, first, a three-dimensional model of the outer panel to be actually assembled (to be adopted) and the reinforcing member that reinforces this outer panel, and a three-dimensional model of the mastic adhesive 11 to be applied to this outer panel are input into known CAE simulation software. Furthermore, in the mastic distortion prediction step, the displacement coefficient of the mastic adhesive 11 calculated by the above method is input into the CAE simulation software.

[0057] In this embodiment, for example, the material and weight of the exterior panel, the composition of the mastic adhesive 11, and the like are appropriately input into the CAE simulation software as necessary. In this embodiment, non-deformable parts that are fixed by welding or the like and cannot be deformed, and deformable parts that are not fixed and can be deformed, and the like may be set as necessary.

[0058] Then, in the mastic distortion prediction process, the mastic distortion (displacement) of the exterior panel when the exterior panel and the mastic adhesive 11 are heated and cooled under the above-mentioned temperature conditions is predicted by CAE simulation software (CAE simulation).

[0059] <Effects etc.> As described above, in the mastic distortion prediction method of this embodiment, the following steps are carried out to predict the mastic distortion of an exterior panel that occurs when the mastic adhesive 11 that bonds the exterior panel to the reinforcing member that reinforces the exterior panel is heated and cooled by painting and baking.

[0060] Specifically, in the mastic distortion prediction method of this embodiment, first, a first plate member 13, which is sufficiently thinner than the actual exterior panel, and a second plate member 14, which is assumed to be a reinforcing member, are arranged so as to sandwich the mastic adhesive 11 and inter-face jigs 12 of a predetermined height arranged on both ends of the mastic adhesive 11, and a test apparatus 1 is prepared in which both ends of the first plate member 13 and the second plate member 14 are clamped together with the inter-face jigs 12 with fixing clips 15 to restrain the movement of each plate member, and then, while changing the amount of mastic adhesive 11 applied, the inter-face displacement amount, which is the amount of change in the inter-face distance before and after painting and baking, is measured for each amount of application, and an inter-face displacement amount measurement process is performed in which the displacement tendency of the mastic adhesive 11 due to expansion or contraction is determined.

[0061] Next, a first plate member 13 (corresponding to the third plate member described in claim 1) representing an actual exterior panel and a second plate member 14 representing a reinforcing member are arranged so as to sandwich the mastic adhesive 11 and the inter-face jigs 12 arranged on both ends of the mastic adhesive 11, and a test device 1 is prepared in which the movement of each plate member is restrained by clamping both ends of the first plate member 13 and the second plate member 14 together with the inter-face jigs 12 with fixing clips 15.Then, while changing the amount of mastic adhesive 11 applied, painting and baking are performed for each amount of application, and then a maximum displacement measurement process is performed in which the maximum displacement of the mastic adhesive 11 is measured with the fixing clips 15 and the inter-face jigs 12 removed.

[0062] Finally, a mastic distortion prediction process is carried out, in which the mastic distortion of the exterior panel when mastic adhesive 11 is applied between the exterior panel and the reinforcing member and painting and baking are performed is predicted by CAE simulation based on the maximum displacement amount described above and a three-dimensional model of the exterior panel and the reinforcing member.

[0063] In this way, according to the mastic strain prediction method of this embodiment, the mastic strain of the exterior panel is predicted using the maximum displacement amount of the mastic adhesive 11, which reflects both the expansion and contraction caused by painting baking, so that the strain in the expanding and contracting directions of the exterior panel can be predicted with high accuracy. EXAMPLES

[0064] Next, the method for predicting mastic distortion according to the present invention will be further described with reference to examples, although the present invention is not limited to the following examples.

[0065] <Example 1> The test apparatus shown in Figure 1 was prepared and a unit area (100 cm 2 mastic adhesive application amount (g / cm 2 While changing the coating amount, the interfacial displacement (mm) before and after painting and baking was measured for each coating amount, and the expansion or contraction displacement tendency (mastic properties) of the mastic adhesive was determined (interfacial displacement measurement step). In Example 1, mastic adhesive A was used as the mastic adhesive. In addition, the coating amount of mastic adhesive A was set to 1.5 g / cm 2 , 2.0g / cm 2 , 2.5g / cm 2 The interfacial displacement was measured for each coating amount.

[0066] The first plate member has a thickness of 0.3 mm and an area of ​​100 (10 × 10) cm 2 The second plate member was a steel plate with a thickness of 1.6 mm and an area of ​​100 (10 × 10) cm. 2The steel plates used were 100 mm in height. The height of the face-to-face jig (face-to-face distance before painting and baking) was 5 mm. As shown in Figure 1, the movement of each plate member was restrained using a fixing clip.

[0067] The temperature conditions for baking the paint were as follows: ·Heating temperature: 180℃ Heating rate: 40℃ / min Heating temperature maintenance time: 20 minutes ·Cooling temperature: 50℃ ·Cooling rate: 10℃ / min After cooling, the test apparatus was allowed to cool to room temperature (23°C).

[0068] FIG. 6 is a diagram showing the results of measuring the amount of inter-surface displacement for each applied amount of mastic adhesive, and the solid line shows the results of measuring the amount of inter-surface displacement when mastic adhesive A was used.

[0069] Next, a test device was prepared in which the first plate member was changed, and the unit area (100 cm 2 mastic adhesive application amount (g / cm 2 After that, the maximum displacement (mm) of the mastic adhesive was measured with the fixing clip and the inter-face jig 12 removed (maximum displacement measurement process). In the maximum displacement measurement process, the first plate member was 0.6 mm thick and had an area of ​​100 (10 × 10) cm. 2 A test device similar to that used in the interfacial displacement measurement process was prepared, except that the steel plate was 1.5 g / cm2. 2 , 2.0g / cm 2 , 2.5g / cm 2 The maximum displacement (mm) of the mastic adhesive was measured for each coating amount. The temperature conditions during baking were the same as those in the interfacial displacement measurement process.

[0070] Fig. 7 shows the results of measuring the maximum displacement of mastic adhesive for each application amount, with the solid line showing the results of measuring the maximum displacement of mastic adhesive A. The straight line drawn near the maximum displacement of mastic adhesive A (solid line) shows the linear approximation equation (y=0.65x-0.6833) of the solid line portion. This linear approximation equation is a mathematical expression of the maximum displacement in relation to the amount of mastic applied per unit area of ​​the exterior panel, and a displacement coefficient that changes depending on the type of mastic adhesive, the surface distance, and the material and thickness of the exterior panel was determined based on this equation.

[0071] Finally, a 3D model of the outer panel (steel plate with a thickness of 0.6 mm) to be actually incorporated and the reinforcing member (steel plate with a thickness of 1.6 mm) that reinforces this outer panel, as well as mastic adhesive A (application amount 3.2 g / cm) to be applied to this outer panel were created in known CAE simulation software. 2 ) and the displacement coefficient obtained based on the maximum displacement measured in the maximum displacement measurement process were input, and the mastic distortion (displacement) of the exterior panel when mastic adhesive A is heated and cooled under the temperature conditions described above was predicted using CAE simulation software.

[0072] <Example 2> In Example 2, the mastic adhesive used was changed to mastic adhesive B, and otherwise the mastic distortion of the exterior panel was predicted in the same manner as in Example 1. The results of measuring the inter-surface displacement for each application amount when mastic adhesive B was used are shown by the dotted lines in Figure 6. Also, the results of measuring the maximum displacement for each application amount of mastic adhesive B are shown by the dotted lines in Figure 7 (the straight line drawn near the maximum displacement of mastic adhesive B (dotted line) indicates the linear approximation equation (y=-0.12x-0.1333) for the dotted line portion).

[0073] <Example 3> In Example 3, the mastic adhesive used was changed to mastic adhesive C, and the first plate member used in the maximum displacement measurement step had a thickness of 0.8 mm and an area of ​​100 (10 × 10) cm. 2The aluminum plate was used, and apart from these, the mastic distortion of the exterior panel was predicted in the same manner as in Example 1. The results of measuring the inter-surface displacement for each application amount when mastic adhesive C was used are shown by the dashed-dotted line in Figure 6. The results of measuring the maximum displacement for each application amount of mastic adhesive C are shown by the dashed-dotted line in Figure 7 (the straight line drawn near the maximum displacement of mastic adhesive C (dashed-dotted line) indicates the linear approximation equation (y=0.35x-0.35) for the dashed-dotted line portion).

[0074] <Comparative Example 1>

[0075] In Comparative Example 1, mastic adhesive A was used, the outer panel to be actually assembled was a steel plate with a thickness of 0.6 mm, the reinforcing member was a steel plate with a thickness of 1.6 mm, and using the temperature conditions described above, the mastic distortion of the outer panel was predicted using a conventional method (the thermal expansion coefficient of the mastic adhesive was calculated using the method described in JP 2019-59887 A). <Comparative Example 2>

[0076] In Comparative Example 2, mastic adhesive B was used, the outer panel to be actually assembled was a steel plate with a thickness of 0.6 mm, the reinforcing member was a steel plate with a thickness of 1.6 mm, and using the above-mentioned temperature conditions, the mastic distortion of the outer panel was predicted using a conventional method (the thermal expansion coefficient of the mastic adhesive was calculated using the method described in JP 2019-59887 A).

[0077] <Evaluation> The outer panel (0.6 mm thick steel plate) and the reinforcing member (1.6 mm thick steel plate) to be actually installed were bonded using mastic adhesive A under the above-mentioned temperature conditions, and the mastic distortion at this time was measured. In addition, the mastic distortion was also measured in the same way when the panel was bonded using mastic adhesive B. Outer panel 100 cm 2 The mastic application amount is 3.2g / cm 2 It was decided.

[0078] Then, for the case where mastic adhesive A was used for bonding, the actual measured values ​​and the predicted results of Example 1 and Comparative Example 1 were compared. Also, for the case where mastic adhesive B was used for bonding, the actual measured values ​​and the predicted results of Example 2 and Comparative Example 2 were compared.

[0079] Table 1 shows the measured mastic strain for each mastic adhesive, the predicted results for the Examples, and the predicted results for the Comparative Examples. When mastic adhesive A was used for bonding, the measured mastic strain was 1.2 mm, the predicted result for Example 1 was 1.4 mm, and the predicted result for Comparative Example 1 was 2.2 mm. When mastic adhesive B was used for bonding, the measured mastic strain was -0.4 mm, the predicted result for Example 2 was -0.3 mm, and the predicted result for Comparative Example 2 was 0.1 mm.

[0080] As can be seen from these results, when mastic adhesive A was used for bonding, the predicted results of Example 1 were closer to the actual measured values ​​than the predicted results of Comparative Example 1, and it was confirmed that Example 1 could predict the mastic strain with greater accuracy than Comparative Example 1. Furthermore, when mastic adhesive B was used for bonding, the predicted results of Example 2 were closer to the actual measured values ​​than the predicted results of Comparative Example 2, and it was confirmed that Example 2 could predict the mastic strain with greater accuracy than Comparative Example 2.

[0081] [Table 1]

[0082] Next, the outer panel (0.8 mm thick aluminum plate) and the reinforcing member (1.6 mm thick steel plate) to be actually assembled were actually bonded using mastic adhesive C under the above-mentioned temperature conditions, and the mastic distortion at this time was measured. 2 The mastic application amount is 3.2g / cm 2 The surface distance was 6 mm. When mastic adhesive C was used for bonding, the actual measured values ​​were compared with the predicted results of Example 3.

[0083] Table 2 shows the actual measured value of mastic distortion caused by mastic adhesive C and the predicted result of Example 3. When mastic adhesive C was used for bonding, the actual measured value of mastic distortion was 1.0 mm, and the predicted result of Example 3 was 0.8 mm. As a result, it was found that when mastic adhesive C was used for bonding, predicted results close to the actual measurements could be obtained.

[0084] [Table 2] [Explanation of symbols]

[0085] 1 Test equipment 11 Mastic adhesive 12 Surface jig 13 First plate member 14 Second plate member 15 Fixing clip

Claims

1. A method for predicting mastic distortion of an exterior panel that occurs when a mastic adhesive that bonds an exterior panel to a reinforcing member that reinforces the exterior panel is heated and cooled by painting and baking, comprising: a surface-to-surface displacement measurement process in which a first plate member that is sufficiently thinner than an actual exterior panel and a second plate member representing the reinforcing member are arranged so as to sandwich the mastic adhesive and surface-to-surface jigs having a predetermined height arranged on both ends of the first plate member and the second plate member, and both ends of the first plate member and the second plate member are clamped together with the surface-to-surface jigs with fixing clips to restrain the movement of each plate member, and while changing the amount of application of the mastic adhesive, a surface-to-surface displacement amount that is the amount of displacement of the surface-to-surface distance before and after painting and baking is measured for each amount of application, thereby determining the displacement tendency of the mastic adhesive due to expansion or contraction; a maximum displacement measurement step in which a third plate member representing an actual exterior panel and a second plate member representing the reinforcing member are arranged so as to sandwich the mastic adhesive and the inter-face jigs arranged on both ends thereof, and both ends of the third plate member and the second plate member are clamped together with the inter-face jigs with fixing clips to restrain the movement of each plate member, and a paint baking is carried out for each amount of application while changing the amount of application of the mastic adhesive, and then the maximum displacement amount of the mastic adhesive is measured with the fixing clips and the inter-face jigs removed; a mastic distortion prediction process for predicting a mastic distortion of the outer panel when the mastic adhesive is applied between the outer panel and the reinforcing member and then painted and baked, by CAE simulation, based on the maximum displacement and a three-dimensional model of the outer panel and the reinforcing member; Including, A method for predicting mastic distortion.

2. The maximum displacement amount is converted into a coefficient in advance by mathematically formulating the relationship with the amount of mastic applied per unit area of ​​the exterior panel, The converted coefficients are used to predict mastic distortion by CAE simulation. The method for predicting mastic distortion according to claim 1 .

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