Measuring and testing – By abrasion – milling – rubbing – or scuffing
Reexamination Certificate
2001-12-03
2003-02-18
Raevis, Robert (Department: 2856)
Measuring and testing
By abrasion, milling, rubbing, or scuffing
Reexamination Certificate
active
06520000
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
The present application is a continuation of International Application No. PCT/SE00/01129, filed May 31, 2000, which claims priority to Swedish Application No. 9902075-2, filed Jun. 3, 1999.
BACKGROUND OF INVENTION
1. Technical Field
The present invention relates to a method and device for abrasion determination on a surface subjected to abrasive forces. More specifically, the invention relates to a method and device for determining abrasions on a substrate having at least two distinguishable superimposed layers that covered each other. Even more particularly, the invention relates to such a method and device for assessment of the abrasive forces to which an individual is exposed upon impact against an airbag during inflation of the airbag or against interior surfaces.
2. Background Information
Contact between two surfaces causes various types of effects that may be harmful to at least the more sensitive one of the two surfaces. Examples of such effects include pressure, friction and abrasive forces.
Reference to abrasive forces herein should be understood to refer to the forces that occur when an uneven surface slides against another surface under pressure, such as sandpaper against a piece of wood. Another example is human skin sliding against rough surfaces, such as asphalt paving or coarse textiles. The furrows that the scraping or abrasion causes on the human skin may result in injuries with consequential bleeding and scarring.
Abrasive forces may be of different types. For example, the contact surface may vary in coarseness and/or be applied with varying pressure. The coarser the surfaces and/or higher pressures, the more severe the abrasions. The more severe the abrasive forces, the higher the risks of abrasion-induced injuries and, as a consequence, of scarring.
While several methods have been developed for measuring pressure-induced damages, there still exists no satisfactory method for accurately assessing the abrasive forces that arise, for example, to the human skin in situations as described above. For example, the cloth of an airbag brought into contact with a person's skin inside the car can cause abrasion injuries. The contact surface of the airbag varies according to its stage of inflation. In other words, it is important to study the detrimental effects that an airbag may have on the human skin in order to determine any abrasive forces. By doing so, airbags that cause as little abrasion as possible upon contact with the human skin can be developed.
In one method used for determining whether two surfaces come into contact with one another in vehicle crash tests, exposed body parts, such as the arms and the face of a crash-test dummy, are covered with a coating of paint. The coating can vary from a simple coating of lipstick to a more complex solution of pigments mixed with a hardener for suitable hardness. However, the information gained from these tests is limited. With this method, it is possible to only determine whether the two surfaces have been in contact with one another or not.
Another problem with the above method occurs in spraying the pigment solution onto the crash-test dummy. By spraying on the coating, it is difficult to obtain an evenly thick coating throughout. An even coating is necessary in order to obtain a comparable indication across the entire relevant area.
German Patent Specification DE 24 48 784 A1 describes a method and device for examining the configuration of a glass slab along its outer periphery. The inspection is performed by placing the slab in a check frame. Along a comparatively narrow section of the glass slab corresponding to its outer periphery, several layers of paper having different colors are applied, one on top of the other. As the glass slab is placed inside the frame, the slab, should its shape not coincide with that of the frame, scrapes off the paper layers where the slab configuration does not agree with that of the frame. Depending on where and how much the layers are scraped off, it is possible to evaluate the configuration of the glass slab.
SU 1596228 describes a technique in which the rotating cutting tools of an earth milling machine are coated with several layers of paint in order to determine which sections of the tool are most exposed to wear. In this case, scraping off the paint occurs gradually in the same place as the cutting tools are rotated, i.e., the larger the number of rotations, the more severe the scraping effects. However, the results of this technique only indicate that a certain spot on the cutting tool has a greater exposure to more scraping or wear damage than another spot.
Japanese Patent No. 60-177243 describes a device and method for discovering irregular wear on vehicle tires. As indicated in the Abstract, part of the tire is coated with several differently colored layers of rubber. In this case the scraping-off is gradual on those places having the greatest exposure to scraping effects as the tire is rotating, i.e., the larger the number of rotations, the more severe the scraping effects. Still, the results only indicate that one spot on the tire is more exposed to scraping damage than another spot.
In view of the above, there is a need for a method that allows a more precise assessment of the severity and extent of abrasive forces, such as those which a person may be exposed to upon impact with an inflated airbag, or against other interior surfaces of a vehicle. Further, there is a need for a device for implementing the method that is as simple as possible while at the same allowing a precise assessment of the abrasion.
SUMMARY OF INVENTION
The present invention provides a method and device for determining the abrasion or amount thereof on a surface subjected to abrasive forces. According to the invention, at least two distinguishable superimposed layers cover each other over a base or substrate. The layers are removable by scraping. An abrasion is measured by subjecting the layer-coated substrate to abrasive forces, which is followed by reading the degree of penetration through one or more of the distinguishable layers. Each layer is calibrated to correspond to a predetermined amount of abrasive force upon penetration of the respective layer. This is accomplished by varying the adhesion to the layer or substrate underneath. Further, the abrasive force required to scrape off a certain layer decreases the further from the substrate that the layer is located.
In one embodiment, the thickness of each individual layer decreases the further from the substrate that the layer is located. As a consequence, the adhesion of the layers decreases accordingly.
In one embodiment, the method of the present invention involves reading and assessing the location of the penetration on the substrate and/or the size of the scraped off area on the respective area.
In one embodiment, the layers have different reactants and/or crystalline properties. The layers may also have different reflection coefficients. In doing so, the various layers can react differently to radiation such that the area exposed to abrasive force can be radiated in order to identify areas exposed to abrasive force of different strength and/or different colors and or different patterns.
The method according to the invention involves the steps of applying on a substrate two or more distinguishable superposed layers that cover each other. These layers may be scraped off. The measurement of abrasion is determined by exposing the substrate with the layers applied thereon to abrasive forces. This is followed by reading the degree of penetration, if any, through one or several of the different layers, and assessing the extent of the abrasive forces. Each layer is calibrated to correspond to a premeasure of abrasive force required to penetrate the respective layer, by varying the layer's ability of adhering to the layer or substrate underneath, the calibration being such that the measure of abrasive force required to scrape off a certain layer decreases the closer to the free surface that the
Lidén Jenny
Nilsson Tomas
Palmertz Camilla
Howrey Simon Arnold & White , LLP
Raevis Robert
Volvo Car Corporation
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