JP6919636B2 - Simple test method for snow strength of automobiles - Google Patents

Description

The present invention relates to a simple test method for evaluating the snow strength of an automobile.

Panel parts for automobiles include outer panel parts called outer parts and inner panel parts such as floors and dash lowers. This automobile panel part is a group of parts having a wide projected area. For this reason, the weight reduction amount of the automobile panel parts due to the reduction of the plate thickness is remarkably large as compared with other skeletal parts. Among them, the roof panel parts have a large projected area, so that the effect of weight reduction by thinning the plate is particularly large.
Roof panel parts are parts that have a great effect on weight reduction, especially in vehicles such as vans and minivans. In addition, there is a tendency for the center of gravity of the vehicle body to be lowered due to the desire for excellent maneuverability and enjoyment of driving, so there is a particularly high need for weight reduction of the roof at the upper part of the vehicle.

On the other hand, one of the required performance of the roof is snow strength. When a car is traveling outdoors or parked outdoors, snow may accumulate on the roof panel and the load may cause the roof panel to flip. The snow strength is the strength required to prevent the roof panel from being inverted due to the weight of the snow and causing the panel to not return to its original shape and to undergo permanent deformation. This snow strength is a special performance required only for roof panels. Snow strength, which is called strength, can be considered as a type of rigidity because it is related to the reversal (buckling) of the panel.

However, regardless of the season, a snowmaking machine is required and a large space capable of maintaining a low temperature is required in order to actually cover the automobile with snow for the test. Furthermore, it is necessary to actually make a prototype of the vehicle for evaluation. Here, as a substitute for snow cover, a method of placing a hydraulic load or earth and sand on the entire surface of the roof panel can be considered. However, with such a load method, it is practically difficult to realize an evenly distributed load because the area of the roof panel is large.

Conventionally, as a strength / rigidity test of a panel component for an automobile, for example, there is a technique described in Patent Documents 1 and 2. Patent Document 1 describes a technique relating to an evaluation test of tension rigidity in which a metal panel is pushed by an indenter. Further, Patent Document 2 discloses a method of dent evaluation in a portion where a sharp curvature changes (a portion such as a character line or a bead assigned to an outer panel). However, these are all cases where the load is locally applied, and relate to the evaluation of the tension rigidity and the dent resistance when a person pushes the panel with a finger or a hand. Such an evaluation is not an evaluation in a test in which an evenly distributed load is applied to the entire surface of the panel, such as snow strength, but a performance that is not emphasized in a roof panel that is relatively rarely touched by humans.

Further, as a test related to roof panel performance, there is a hail drop test disclosed in Patent Document 3 and Patent Document 4. Especially in Europe and the United States, deformation of automobile panel parts (roof, hood, etc.) due to hailstorm has become a problem. However, although the range to be evaluated is the entire roof panel as in the case of snow strength, the load is a load condition simulating a state in which each hail hits the roof panel individually. Therefore, the hail drop test is also a test form in which a load is locally applied.

At present, the evaluation test of the snow strength of the roof is carried out by making a prototype of the vehicle itself, placing weights on the surface of the roof panel in order, and sequentially applying a load. However, when the surface of the roof panel is partially and sequentially loaded with a weight, in the process, the load state is not evenly distributed but unevenly distributed on the entire surface of the roof panel. .. Therefore, it is considered that the evaluation accuracy of the snow strength is insufficient in such a test.

Japanese Patent No. 5024152 Japanese Patent No. 59197882 Japanese Unexamined Patent Publication No. 2010-97098 Japanese Unexamined Patent Publication No. 2011-75307

The present invention has been made by paying attention to the above points, and an object of the present invention is to provide a test method capable of easily and accurately evaluating the snowfall strength of an automobile.

It is also conceivable to create a miniature model of the actual vehicle to be evaluated and conduct an evaluation test of snow strength. However, when simply making a miniature car with a model that is a fraction of the actual car, it is necessary to make dies for the number of parts, and it is also necessary to miniaturize the welding machine. And it is not realistic to carry out such man-hours and investment for each vehicle model development.
Therefore, the inventor has considered a method that can qualitatively verify the effectiveness of the snow strength countermeasure in consideration of the component structure and the design shape of the roof panel without faithfully reproducing the test on the actual vehicle. Then, the inventor interprets the upper part (upper body) of the vehicle body as an evaluation "base", manufactures the base (upper body) as a rigid body mass, and separately manufactures a roof panel (roof outer panel) on it. ) Is put on the model and used for evaluation.

That is, in order to solve the problem, in the simple test method for snow strength of an automobile according to one aspect of the present invention, a roof model having the same size as the roof panel to be evaluated or a shape obtained by reducing the roof panel is prepared, and the roof model of the roof model is prepared. The gist is that an evenly distributed load is applied to the surface of the roof model from above with the outer peripheral portion fixed to the base, and the amount of deformation of the roof model due to the load is measured.
The roof model is preferably a miniature shape with a reduced roof panel in consideration of model fabrication and realization of an evenly distributed load.
As the load of the evenly distributed load, it is preferable to use a soft rubber sheet panel in consideration of the realization of the evenly distributed load.

According to one aspect of the present invention, by using a simple model around the roof panel, it is possible to reduce the cost and man-hours and easily evaluate the snow cover strength. As a result, it is possible to easily verify the effect of countermeasures against snow cover, and more effective component design becomes possible.
In particular, when a roof model with a miniature roof panel is adopted, the area where the evenly distributed load is applied becomes smaller, it becomes easier to apply the evenly distributed load to the roof model, and the work space used in the test becomes smaller. Can be done.

It is a figure which shows the example of the roof model. It is a figure which shows the example of the foundation. It is a figure which shows the restraint example of the base. It is a figure which shows the example of the rattling prevention measure of a roof model. It is a figure which shows the example which loaded the rubber sheet panel as a weight. It is a figure which shows the relationship between displacement and snow load.

Next, an embodiment of the present invention will be described with reference to the drawings.
The evaluation method of the present embodiment includes a roof model, a base for restraining the roof model, a displacement meter for measuring the displacement (deformation amount) of the roof model in the plate thickness direction, and a weight for realizing an evenly distributed load. ..
<Roof model>
The roof model 1 is a model that imitates the roof panel to be used in the actual vehicle to be evaluated, as shown in FIG.
The roof model 1 may be a model having the same size as the roof panel, but a miniature model in which the roof panel is scaled (reduced) is preferable.

In the following description, a case where a miniature model with a reduced roof panel is used as the roof model 1 will be described as an example.
It is thought that the larger the scale, the higher the evaluation accuracy of the reduced size, but considering the ease of evaluation, the smaller the scale is preferable. From this point of view, the scale is set to, for example, 1/5 to 1/15 in a plan view. The large scale means that the degree of reduction is small.
In the following description, a case where 1/10 is adopted as the scale in a plan view will be described as an example.

Here, in order to reduce the size influence caused by the reduction of the dimensions in the plan view, the roof model 1 is preferably made as thin as possible according to the reduction of the dimensions. However, for example, when the roof model 1 is made of a resin having a low Young's modulus, the rigidity of the mating portion cannot be ensured, and the necessary test may not be possible. Therefore, it is effective to use the same material (iron or aluminum metal) as the roof outer panel of the actual vehicle or a material having the same Young's modulus as the material of the roof model 1.

However, even if the same material (iron or aluminum metal) as the roof outer panel of the actual vehicle is used, the smaller the scale, the thicker the plate thickness will be if the same scale as the scale in plan view is adopted. It may not be suitable for evaluation because it becomes too thin to secure rigidity. In such a case, the scale of the plate thickness is set to be relatively large, that is, the plate thickness is set to be relatively thick with respect to the scale in the plan view.
Even if the scale of the plate thickness is set to a large scale, it is possible to accurately evaluate the snow strength by setting the evaluation standard to the same plate thickness.

<Foundation>
The base is a component that fixes the outer circumference of the roof model 1 and restrains the roof model 1 without rattling. Since the roof panel and the upper body of the vehicle body are usually joined by welding, it is preferable to fix the outer periphery of the roof model 1 so that the base does not rattle.
As the base 2, for example, as shown in FIG. 2, an upper model having a shape in which the upper body, which is the upper portion of the vehicle body, is reduced to the same scale as the roof model 1 is adopted. However, the material of the upper model does not have to be the same as that of the upper body. The upper model may be made of resin.

The upper model may be produced by, for example, a three-dimensional printer or press molding.
When a three-dimensional printer is used, the upper model can be produced with high accuracy. When manufacturing with a three-dimensional printer, for example, the upper model is made of resin.
Here, it is preferable that the mating portion between the base 2 and the roof model 1 does not rattle or the like. Therefore, the shape of the mating portion of the base 2 with the roof model 1 is required to have a reproduction accuracy of a predetermined value or higher. Therefore, it is effective to produce the base 2 as a "lump" with a three-dimensional printer. The material may be metal or resin, but it is necessary to increase the rigidity in order to exhibit the function of the base 2. In the case of a resin with a low Young's modulus, it is effective to take structural measures such as inserting a beam to improve the flexural rigidity and torsional rigidity.

The base 2 made of the upper model may be manufactured by press molding. Since the size is small, it is only necessary to manufacture a small mold, and there is no problem in applying an inexpensive mold such as a ZAS mold.
As for the restraint (joint) between the base 2 and the roof model 1, if it can be ensured that the roof model 1 does not shift laterally, mechanical clamps, tapes, adhesives, etc. are used as shown in FIGS. 3 and 4. You may. FIG. 3 shows an example in which the restraint device 3 is arranged on the outer periphery of the base 2 to suppress the deformation of the base 2. FIG. 4 shows an example of temporarily fixing with the tape 5.

<Displacement meter>
The displacement meter 4 is arranged below the roof model 1 and measures the displacement (deformation amount) of the roof model 1 in the plate thickness direction with or without contact. FIG. 3 illustrates a case where the displacement meter 4 is a contact displacement meter 4.
The displacement meter 4 may be a device that measures a three-dimensional shape by an optical method or the like provided with a grid.
The measurement position of the displacement meter 4 is set to a portion where the displacement is relatively large in a simulation analysis such as CAE. Two or more displacement meters 4 may be set to measure displacements at a plurality of locations.

<Weight>
The weight of the present embodiment is composed of a plurality of rubber sheet panels having the same shape as the roof model 1 and having the same area as the roof model 1 in a plan view. Equivalent means that the rubber sheet panel has a size that can cover 80% or more, preferably 95% or more of the area of the roof model 1, for example.
By laminating the rubber sheet panel 6 on the roof model 1 as shown in FIG. 5, the equally distributed load to be loaded can be easily changed.
It is preferable that the rubber sheet panel 6 is deformed so as to fit the surface shape of the roof model 1 so that the load is as evenly distributed as possible. For example, as the rubber sheet panel 6, the material of the rubber sheet panel 6 may be a soft material, or the rubber sheet panel 6 having a thin plate thickness may be adopted. In particular, for the rubber sheet panel 6, it is preferable to use a soft rubber material for at least the bottom rubber sheet panel 6 in order to obtain a degree of adhesion to the surface shape of the roof model 1.
A plurality of such rubber sheet panels 6 are prepared and placed in sequence to change the load. Then, the current load is determined by the weight and the number of the laminated rubber sheet panels 6.

<Operation and others>
The outer circumference of the roof model 1 is fixed to the base 2 and restrained. Then, every time the rubber sheet panel 6 is laminated on the roof model 1, the displacement meter 4 measures the amount of downward displacement of the roof model 1 with the displacement meter 4.
In this way, the relationship between the evenly distributed load applied and the displacement amount of the panel is acquired.
Then, for example, by comparing the evaluation standard that is the standard of the relationship between the equally distributed load to be loaded and the displacement amount of the panel and the above-mentioned measured relationship, the displacement amount with respect to the snow load is smaller than the base standard. It is evaluated whether the snow strength is improved by whether or not it is.

The roof model 1 of the evaluation standard is acquired by using a model having the same scale and the same plate thickness as the roof model 1 to be evaluated. For example, the roof model 1 of the evaluation standard is manufactured from the roof panel of the current vehicle. The evaluation criteria may be determined by analysis such as CAE.
Once the evaluation standard data is determined, the degree of improvement in snow intensity can be evaluated by comparing with the evaluation standard.
According to this embodiment, a miniaturized simple snow strength test model is used.

In the past, in order to verify the effect of snow strength measures, it was not possible to accurately evaluate the snow strength without making a prototype of the automobile itself, but in this embodiment, the cost and man-hours are low, and the snow strength can be easily evaluated. Evaluation becomes possible. As a result, the effect of countermeasures can be easily verified, and more effective component design becomes possible. The reduction rate from the actual vehicle is not particularly limited. However, when the base 2 is manufactured by a three-dimensional printer, the size of the roof model 1 is preferably 500 mm × 500 mm or less because it depends on the limitation of the manufacturing size of the base 2.

Further, in the present embodiment, it is possible to qualitatively verify the effect of the snow strength countermeasure while considering the component structure and the design around the roof panel, instead of faithfully reproducing the actual vehicle test. That is, in the present embodiment, the vehicle body portion (upper body) is interpreted as an evaluation "base", the base 2 (upper body) is manufactured as a rigid body mass, and a separately manufactured miniature model of the roof outer panel is placed on the base 2 (upper body). By evaluating the above, it becomes possible to easily evaluate.

Next, an example based on this embodiment will be described.
The roof model 1 was manufactured by press molding to 1/10 the size of the roof panel of the actual vehicle. The material of the roof model 1 is the same as that of the roof outer (made of iron). In this embodiment, as the roof model 1, two levels of models, a roof model A having a plate thickness of 0.3 mm and a roof model B having a plate thickness of 0.5 mm, were produced. The shape of the roof model 1 is the shape shown in FIG.
The shape of 1/10 size of the upper body in the actual vehicle was set as the base 2, and the base 2 was manufactured by a three-dimensional printer. The base 2 is made of resin.
Then, as shown in FIG. 3, the outer peripheral side surface of the base 2 is fixed on a frame made of an aluminum frame to gain rigidity. Further, the contact type displacement meter 4 was set so as to hit the lower surface of the roof model 1 from the bottom side. This makes it possible to measure the deformation of the roof model 1 that is hidden by the rubber sheet panel during the test.

Then, as shown in FIG. 4, the roof model 1 was attached to the base 2, and the roof model 1 was temporarily fixed to the base 2 with tape in order to prevent the roof model 1 from laterally shifting.
Here, a plurality of rubber sheet panels 6 (220 g per sheet) cut out to the same size as the surface of the roof model 1 are prepared.
Then, as shown in FIG. 5, the rubber sheet panels 6 are sequentially stacked on the roof model 1 fixed to the base 2, so that the load load in an even distribution is increased. Further, each time the rubber sheet panels 6 were laminated, the displacement of the roof model 1 in the plate thickness direction was measured with the displacement meter 4.

The measurement results are shown in FIG. The measurement result shown in FIG. 6 shows the relationship between the displacement of the roof model 1 and the snow load (equally distributed load by the rubber sheet).
As can be seen from FIG. 6, the roof model B having a plate thickness of 0.5 mm has a higher rigidity than the roof model A having a plate thickness of 0.3 mm, and the evaluation of the snow load based on the present invention is made. However, it can be seen that it can be evaluated properly. Here, the roof model A and the roof model B are panels having the same shape and the same material except for the plate thickness.

Here, in FIG. 6, C has the same dimensions as the roof model B and is made of the same material, but the shape is different from the roof model B, and the roof model is made of a plate material flat in the width direction (plate thickness: 0). .5 mm).
The displacement and snow load of the roof model 1 acquired by a model such as the roof model C may be used as evaluation criteria, and the degree of improvement in snow strength may be used as a reference for evaluation.
Even if the roof model 1 has the same shape, the snow strength can be changed by changing the material of the roof model 1.

1 Roof model 2 Base 3 Restraint device 4 Displacement meter 6 Rubber sheet panel

Claims (3)

Prepare a roof model of the same size as the roof panel to be evaluated or a reduced shape of the roof panel, and with the outer peripheral portion of the roof model fixed to the base, apply an evenly distributed load from above to the surface of the roof model. , Measure the amount of deformation of the roof model due to the load,
The equally distributed load is applied by placing a rubber sheet panel having the same shape as the roof model on the roof model, and by sequentially stacking the rubber sheet panels, the equally distributed load to be applied is changed. do,
A simple test method for snow strength of automobiles. As the base, snow strength simple test method for automobile according to claim 1 which comprises using the upper model is a model of the upper body constituting the upper part of the automobile body supporting the roof panel. The roof model has a reduced shape of the roof panel.
The simple test method for snow strength of an automobile according to claim 2 , wherein the upper model is manufactured by a three-dimensional printer, and the roof model is manufactured of the same metal material as the roof panel to be evaluated.

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