Patent Application
20160299074
This application claims priority to European Patent Application No. 15001052.8, filed Apr. 13, 2015, which is incorporated herein by reference in its entirety.
The embodiments described herein relate to a method for testing the surface quality of a component, in particular of a CFRP component, to demonstrate the suitability of the component for coating or bonding, in which method the surface of the component is wetted with a test liquid. In addition, the embodiments described herein relate to a device for carrying out the method on a component.
This relates to the production of components to be coated or bonded, in which a minimum surface quality has to be ensured so as to be able to carry out the coating or bonding procedure without errors. For this purpose, the corresponding component surfaces must have sufficient adhesion and wetting properties. The properties of the component surfaces are usually already determined in a preceding shaping process, such as polymer injection moulding, metal die casting or laminating, since during these shaping processes the components are often contaminated by separating agents based on fluorinated hydrocarbons, silicones, oils or waxes. In mechanical processing by means of tensioning manufacturing methods, the component surface may become contaminated by cooling emulsions and cutting oils.
Such component surfaces are therefore sometimes pre-treated prior to further processing by means of an incredibly complex cleaning or activating step.
DE 10 2005 027 106 B3 discloses a generic method for testing the surface quality of a component. A water spray mist is first produced as the test liquid. This mist is brought into contact with the surface of the component to be tested in order to produce droplets of the spray mist on the surface. In a pre-selected region of the surface to be tested, the droplets thus formed are optically detected and defined in terms of the value distribution of a droplet property, for example volumes, visible surfaces, and sizes and/or shape factors. The value distribution determined is then compared with a reference value distribution in order to determine the surface quality of the pre-selected region.
However, this test method may in some cases only work on completely smooth surfaces. Tests have shown that this method does not necessarily allow for small fault points to be sufficiently recognized. Therefore, the method cannot reliably be used on textured surfaces that occur in a large number of CFRP components, for example, due to grinding processes or peel plies to be removed. In addition, when using water as the test liquid, the component has to be completely dried before it can be further processed.
Other methods for testing surfaces may include IR spectroscopy. Such methods may, however, not be sufficiently surface-sensitive, and not all specific contaminants can be detected using the methods. Furthermore, not all generic test methods can be integrated into an automated manufacturing process.
One idea is to provide a method and a device for testing the surface quality of a component, in particular of a CFRP component having a textured surface, by means of which the suitability of the component for coating and bonding can be reliably determined in a simple manner.
According to the disclosure, a fluorescent primer is applied to the test surface of the component as the test liquid is subsequently dried on the surface and is then irradiated by means of a light source such that regions lacking surface quality become optically visible on the surface.
The solution according to an embodiment is advantageous in particular in that the fluorescent primer used as the test liquid makes it possible, by means of the fluorescence, to visually discern, in a reliable manner, how the surface is covered with contaminants, for example siloxanes, and the integrated primer property improves the adhesion of a coating or adhesive which leads to an increased resistance of the coating or bond to ageing. The method according to the invention can also be used for textured surfaces and even reliably exposes minor fault points.
The fluorescent primer may be sprayed onto the surface. This allows for this specific test liquid to be applied uniformly over the regions of the surface to be tested. This can be carried out either manually or in an automated manner using a spraying apparatus. In order to show components which are difficult to bond, it is even sufficient to apply the specific test liquid in a partially sprinkled manner.
In order to minimize the testing time, it is proposed to dry the sprayed-on florescent primer using a heat source pointing towards the surface. In this case, a radiant heat source should preferably be used so as not to impair the distribution of the test liquid on the surface.
According to some embodiments, the dried fluorescent primer may be irradiated by means of a light source which emits ultraviolet light, known as black light. Ultraviolet light makes it easier to identify the regions lacking surface quality, contaminants being shown by regions which fluoresce to varying degrees. This means that regions having different amounts of contaminants fluoresce to varying degrees. These regions lacking suitability for coating and bonding are converted, at least in part, into regions having sufficient coating or bonding suitability by means of the integrated primer property of the test liquid. Only if the surface were very contaminated would additional treatment thereof be necessary in order to obtain coating or bonding suitability. Therefore, the method according to the embodiment also saves on possible intermediate method steps.
The method according to an embodiment may be carried out using a device that comprises a spraying unit for wetting the surface of the component with the specific test liquid and an additional light source for illuminating the treated surface with ultraviolet light. Within the context of additional automation, a heat source for drying the treated surface more quickly can be added to the device. Furthermore, it is possible to equip the device with an optical camera unit and a downstream evaluation unit in order to automatically test the surface quality of the component by comparing patterns.
The various embodiments will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and:
The following detailed description is merely exemplary in nature and is not intended to limit the disclosed embodiments or the application and uses thereof. Furthermore, there is no intention to be bound by any theory presented in the preceding background detailed description.
According to
In order to automate the test method, an optical camera unit 7 is also provided in the example device and detects, as image signals, the regions on the surface 3 of the component 1 which lack surface quality. A downstream electronic evaluation unit 8 compares the patterns of the detected image signals with stored image patterns in order to identify and display significant regions lacking surface quality.
In the automated test method, the component 3 is passed through the device in the arrow direction shown, the test liquid 4 first being applied to the surface 3 of the component 1 at a station I.. At a second station II., the sprayed-on fluorescent test liquid 4 is dried by means of a radiating heat source 5 pointing towards the surface 3. At a third station III., regions of the component 1 which lack surface quality are detected and evaluated by means of an ultraviolet light source 6 in combination with an optical camera unit 7.
As a result of the primer property integrated in the test liquid 4, at least some of the impurities can be rendered safe, and improved adhesion suitability is produced for subsequently coating the component with a top coat or bonding it to another component, without requiring a cleaning step. However, if the test method reveals additional and larger regions having comparatively poorer surface quality, as a result of the test method a decision can be made to first clean the surface of the component 3 before additional surface-sensitive processing is carried out.
The invention is not restricted to the embodiment described above. Rather, modifications are also conceivable and are covered by the scope of protection of the following claims. It is thus also possible, for example, to carry out the test method according to the invention purely by hand. Likewise, a separate heat source can optionally also be dispensed with if, in certain applications, particularly fast drying of the florescent primer on the surface 3 of the component 1 is not necessary.
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the embodiment in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the embodiment as set forth in the appended claims and their legal equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 15001052.8 | Apr 2015 | EP | regional |
