JP6900287B2 - Distortion judgment method - Google Patents

Description

The present invention relates to a strain determination method, and more particularly to a strain determination method for predicting and determining strain of an adherend that occurs when a mastic adhesive is applied to an adherend and heated and cooled to a predetermined temperature.

The mastic adhesive is an adhesive containing a thermosetting material such as a thermosetting resin and a thermosetting rubber. For example, in an automobile bonnet, a door, a roof, etc., an outer panel and a reinforcement are used. It is used as an adhesive that adheres to reinforcing materials such as.

In addition, the mastic adhesive usually contains a foaming agent from the viewpoints of anti-vibration property, cushioning property, filling property, etc., and foams at the time of thermosetting to expand in volume.

For example, in the joint structure of vehicle members constituting a vehicle, a heat-foamable adhesive is used, and after the adhesive is applied to the joint surface of the vehicle member, the adhesive is heat-foamed. It is known (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2015-160561

However, since the heat-foamable adhesive foams and expands when heated and then contracts when cooled, the adhesive portion of the member may be distorted (surface sink mark, bulge, etc.) due to the change in volume. In particular, in recent years, in order to reduce costs and weight, it has been required to reduce the thickness of members such as outer panel panels, but if the thinned members are used, the bonded portion is likely to be distorted.

In such a case, the actually bonded members are visually confirmed, and if the bonded portion is distorted, each member is thickened and retried, which is dealt with by a trial and error. .. However, such a countermeasure has a problem that man-hours and costs are required.

Therefore, an object of the present invention is to provide a strain determination method capable of predicting and determining strain derived from a mastic adhesive with low man-hours and low cost.

The present invention [1] is a strain determination method for predicting and determining the strain of an adherend that occurs when a mastic adhesive is applied to an adherend and heated and cooled to a predetermined temperature. The steps of heating and cooling to a temperature to calculate the thermal expansion coefficient of the mastic adhesive and the shape of the adherend when the mastic adhesive is applied to the adherend and heated and cooled to a predetermined temperature are obtained. Based on the thermal expansion coefficient of the mastic adhesive and the step of calculating as three-dimensional data by CAE simulation based on the three-dimensional model of the adherend, and the three-dimensional data calculated by the CAE simulation. Then, the step of analyzing the curvature of the adherend and quantifying the magnitude of the strain in the adherend to obtain the strain strength, and whether or not the strain strength is within a predetermined threshold range are determined. It includes a distortion determination method including a determination step.

In the strain determination method of the present invention, three-dimensional data is calculated by CAE simulation based on the coefficient of thermal expansion of the mastic adhesive and the three-dimensional model of the adherend, and the adherend is based on the three-dimensional data. The curvature of is analyzed, and the strain strength is obtained by quantifying the magnitude of the strain. Then, pass / fail is determined based on the strain strength.

According to such a strain determination method, since the occurrence of strain can be predicted before the actual bonding, it is possible to reduce the number of steps and the cost without requiring actual retry.

FIG. 1 is a schematic perspective view of a vehicle provided with a roof panel as an example of a determination target of the distortion determination method of the present invention. FIG. 2 is a bottom view of the roof panel in the vehicle shown in FIG. FIG. 3 is a flow chart of an embodiment of the strain determination method of the present invention. FIG. 4 is a schematic view showing a method for measuring the coefficient of thermal expansion of the mastic adhesive. FIG. 5 is a diagram in which the strain strength is mapped to the image data of the adherend. FIG. 6 is a graph that outputs the strain strength along the line AA of FIG.

In FIGS. 1 and 2, the vehicle 1 includes a vehicle body 2 made of a metal steel plate.

The vehicle body 2 includes panel members such as a roof panel 4, a hood panel 5, a front fender panel 6, a side panel 7, a door panel 14, and a back door panel 15, and forms a vehicle interior surrounded by them. ..

The thickness of the panel member is, for example, 1.0 mm or less.

Further, from the viewpoint of cost reduction and weight reduction, the panel member is made thinner. In such a case, the thickness of the panel member is preferably 0.7 mm or less.

In such a vehicle body 2, for example, on the lower surface (vehicle interior side) of the roof panel 4, a plurality of (three in FIG. 1) lean forcements 10 are formed in the vehicle front-rear direction as shown by a broken line in FIG. It is provided at intervals.

The lean forcement 10 is a metal reinforcing material for improving the tension rigidity of the roof panel 4, is erected so as to support the roof panel 4 from below (see the broken line in FIG. 1), and is erected via a mastic adhesive 11. It is adhered to the roof panel 4 (see the solid line in FIG. 2).

The mastic adhesive 11 is a thermosetting and thermofoaming adhesive, for example, a thermosetting material (thermosetting resin, thermosetting rubber, etc.) and a foaming agent (organic foaming agent, inorganic foaming agent, etc.). ) And, if necessary, a filler, a cross-linking agent, a softening agent and the like. The mastic adhesive 11 is not particularly limited, and examples thereof include known mastic adhesives.

The method of adhering the roof panel 4 and the lean force 10 with the mastic adhesive 11 is not particularly limited, but for example, first, the mastic adhesive 11 is first applied to the surface of one of the adherends (for example, the lean force 10). Are arranged at a predetermined interval from each other (for example, six).

Then, in this method, the roof panel 4 and the lean forcement 10 are brought into contact with each other so that the mastic adhesive 11 is interposed between them. As a result, the mastic adhesive 11 is also applied to the other side of the adherend (for example, the roof panel 4).

Then, in this method, the mastic adhesive 11 is heated.

The heating conditions are appropriately set according to the type of the mastic adhesive 11 and the like. As the heating conditions, specifically, the heating temperature is, for example, 150 ° C. or higher, preferably 160 ° C. or higher, and for example, 200 ° C. or lower, preferably 180 ° C. or lower.

Further, the temperature rising time until reaching the above temperature is, for example, 5 minutes or more, preferably 10 minutes or more, and for example, 60 minutes or less, preferably 30 minutes or less.

The maintenance time at the above temperature is, for example, 10 minutes or more, preferably 20 minutes or more, and for example, 60 minutes or less, preferably 30 minutes or less.

Further, in this method, the heated mastic adhesive 11 is cooled (released).

The temperature after cooling is, for example, room temperature, for example, 10 ° C. or higher, preferably 15 ° C. or higher, and for example, 30 ° C. or lower, preferably 25 ° C. or lower. The cooling time (time required for cooling) is, for example, 0.5 hours or more, preferably 1 hour or more, and for example, 5 hours or less, preferably 3 hours or less.

As long as the heating conditions are within the above range, the timing of heating is not particularly limited, and for example, the mastic adhesive 11 can be heated by baking when the roof panel 4 is painted, and then cooled.

Then, by such a method, the mastic adhesive 11 can be foamed and cured, and the roof panel 4 and the lean forcement 10 can be adhered to each other.

On the other hand, the mastic adhesive 11 that has been foamed and expanded by heating shrinks when cooled. Therefore, as the volume of the mastic adhesive 11 changes, a part of the adherend (roof panel 4 and lean forcement 10), specifically, for example, the adhesive portion of the roof panel 4 is distorted (surface sink mark). , Swelling, etc.) may occur.

Then, when the strain strength (the strain strength obtained by quantifying the magnitude of the strain) is unacceptable as a product, the material and thickness of the adherend (roof panel 4 and lean forcement 10) or It is required to change the type of mastic adhesive 11 and the like.

Therefore, in the present invention, the above-mentioned strain, that is, the strain generated when the mastic adhesive 11 is applied to the adherend (roof panel 4 and lean forcement 10) and heated and cooled to the above-mentioned predetermined temperature is described below. Predict and judge by method.

More specifically, in this method, first, the mastic adhesive 11 is heated and cooled to a predetermined temperature by itself, and the coefficient of thermal expansion of the mastic adhesive 11 is calculated (step S1 in FIG. 3).

The method for calculating the coefficient of thermal expansion of the mastic adhesive 11 is not particularly limited, and for example, as shown in FIG. 4, the compression jig (parallel plate type jig) 12 of the viscoelasticity test (slip test) machine can be used. A predetermined amount of mastic adhesive 11 is sandwiched, and the inter-plane distance of the compression jig 12 is set to a predetermined value.

Then, while applying a predetermined load to the mastic adhesive 11, the mastic adhesive 11 is heated and cooled (released) under the same heating conditions as those described above.

At this time, by measuring the inter-plane distance of the compression jig 12, the volume change due to the temperature change of the mastic adhesive 11 is measured.

Then, the coefficient of thermal expansion (linear expansion coefficient) is calculated by a known method from the relationship between the temperature change of the mastic adhesive 11 and the volume change accompanying the temperature change.

The coefficient of thermal expansion of the mastic adhesive 11 varies depending on the type of the mastic adhesive 11, but is, for example, 0.05 × 10 ^-3 / ° C.m or more and 1.5 × 10 ^-3 / ° C.m or less.

Next, in this method, the displacement of the adherend derived from the mastic adhesive 11 is calculated as three-dimensional data by CAE simulation (step S2 in FIG. 3).

More specifically, in this step, first, a three-dimensional model of an adherend (roof panel 4 and lean forcement 10) and an adherend thereof (roof panel 4 and lean) are applied to known CAE simulation software. A three-dimensional model of the mastic adhesive 11 applied to the forcement 10) is input.

Further, in this step, the coefficient of thermal expansion of the mastic adhesive 11 calculated by the above method is input to the CAE simulation software.

Further, if necessary, for example, the material and own weight of the adherend (roof panel 4 and lean forcement 10), for example, the composition of the mastic adhesive 11, etc. are input to the CAE simulation software as appropriate.

In addition, if necessary, a non-deformable part that is fixed by welding or the like in the actual product and cannot be deformed, and a deformable part that is not fixed in the actual product and can be deformed are set. To do.

Then, in this step, the shape change when the adherend (roof panel 4 and lean force 10) and the mastic adhesive 11 are heated and cooled to the above-mentioned predetermined temperature is predicted by the CAE simulation software (CAE simulation). ).

As a result, the shape of the adherend (roof panel 4 and lean force 10) when heated and cooled is calculated as three-dimensional data.

Next, in this method, the curvature of the adherend (roof panel 4 and lean force 10) is analyzed, and the strain strength (strain strength obtained by quantifying the magnitude of strain) in the adherend is obtained (FIG. 3). Step S3).

More specifically, in this step, for example, in Patent No. 5395470, based on the three-dimensional data showing the outer shape of the adherend (roof panel 4 and lean force 10) calculated by the above CAE simulation. The curvature of the adherend is analyzed by the method described.

As a result, the strain strength from the initial shape of each part of the adherend is output as a strain value.

Further, if necessary, the strain strength in the adherend is converted into density data by the method described in Japanese Patent No. 5395470, mapped to the image data of the adherend, and output. More specifically, as shown in FIG. 5, the strain strength is mapped and output as, for example, color density data on the image data of the roof panel 4 (see FIG. 2).

Then, in this method, it is determined whether or not the strain strength obtained above is within a predetermined threshold range (step S4 in FIG. 3).

That is, in this step, the threshold value of the strain allowed as a product, in other words, the limit value of the strain strength allowed as a product is set in advance.

The allowable strain strength is, for example, −50 or more, preferably -30 or more, and for example, +50 or less, preferably +30 or less.

When the strain strength is a negative value, concave distortion such as surface sink marks occurs in the adherend, while when the strain strength is a positive value, the adherend has a convex shape such as a bulge. It is assumed that distortion has occurred.

Further, the limit value (threshold value) of the strain strength allowed as a product is actually set in correspondence with the strain strength allowed when the product is visually confirmed.

Then, the strain strength at a predetermined portion of the adherend (for example, the contact portion between the roof panel 4 and the lean forcement 10 and the mastic adhesive 11) is output, and the strain strength is compared with the above threshold value. ..

For example, as shown in FIG. 6, the strain strength along the line AA of FIG. 5 is output, and the strain strength (solid line in FIG. 6) and the preset threshold value (FIG. 6) are output. (Dashed line) and.

Then, if the strain strength is within the above-mentioned threshold value, the product is accepted. If the strain strength is outside the above threshold value, the product is rejected.

An adherend (roof panel 4 and lean forcement 10) generated when the mastic adhesive 11 is applied to an adherend (roof panel 4 and lean forcement 10) and heated and cooled to a predetermined temperature by such a strain determination method. ) Distortion can be predicted and determined.

Then, when the strain strength is unacceptable as a product, the input data such as the material and thickness of the adherend and the type of the mastic adhesive 11 are changed, and the strain determination method described above is used again. Predict and determine distortion.

According to such a strain determination method, since the occurrence of strain can be predicted before the actual bonding, it is possible to reduce the number of steps and the cost without requiring actual retry.

In the above description, the roof panel 4 is mentioned as the adherend to be adhered by the mastic adhesive 11, but the adherend is not limited to the above, and for example, the hood panel 5 and the front fender panel. 6. Various panel members such as a side panel 7, a door panel 14, and a back door panel 15 can be mentioned.

That is, when various panel members such as the hood panel 5, the front fender panel 6, the side panel 7, the door panel 14, and the back door panel 15 and the reinforcement 10 are bonded by the mastic adhesive 11, the mastic bonding is performed. The strain derived from the agent 11 can be predicted and determined by the strain determination method described above.

4 Roof panel 10 Lean forcement 11 Mastic adhesive

Claims (1)

A strain determination method that predicts and determines the strain of an adherend that occurs when a mastic adhesive is applied to an adherend and heated and cooled to a predetermined temperature.
A step of heating and cooling the mastic adhesive to a predetermined temperature and calculating the coefficient of thermal expansion of the mastic adhesive, and
The shape of the adherend when the mastic adhesive is applied to the adherend and heated and cooled to a predetermined temperature, the coefficient of thermal expansion of the mastic adhesive, and a three-dimensional model of the adherend. Based on the process of calculating as three-dimensional data by CAE simulation,
Based on the three-dimensional data calculated by the CAE simulation, the curvature of the adherend is analyzed, and the strain strength obtained by quantifying the magnitude of the strain in the adherend is obtained.
A strain determination method comprising a step of determining whether or not the strain strength is within a predetermined threshold value.

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