Patent Application
20170361644
The present invention relates to a surface scraper tool for removing coating from a smooth flat surface.
Various activities involve application of a coating to a smooth and flat surface with an adhesive or paint. This may happen intentionally in the context of glass painting or when applying privacy or other protective films to windows. After some time it may be desirable to remove the applied coating again, which often needs to be scraped off with a blade because it cannot be removed easily. More commonly, the unwanted coating is applied accidentally when working on a nearby surface, for example when a window frame is being repainted. While this effect can be minimized by applying masking tape before painting the frame, it cannot always prevent at least some paint from being applied to the window. Sometimes, in order to reduce the time to complete the job, no masking tape is applied and inevitably some of the paint ends up on the window pane.
Many types of scrapers specially designed for removing paint from window panes or other coatings from flat surfaces already exist. In U.S. Pat. No. 4,955,138, a scraper is disclosed with a blade sharp enough to get under the coating, allowing it to be lifted from the flat surface rather than pushing it forward, which requires more force. It is also mentioned that the blade holder secures the blade according to a specific angle with respect to the flat surface in order to ensure maximum scraping efficiency. A similar device is shown in U.S. Pat. No. 4,709,478. In addition to the above-mentioned features, the presented device has long left and right side walls that can be used as guides when scraping along a window frame for example, without damaging it. The bodies of both presented devices slide on the flat surface of the object to scrape, which allows guiding the devices in a stable manner when scraping.
When removing the coating, it is important that no residues are left in areas that are difficult to access, for example in the corner of a window. With the existing devices, this is not easily possible and may require guiding the blade very carefully in order to prevent the surrounding material from getting damaged, since the known devices feature rectangular/right-angled blades that can only reach the corner when they are perfectly placed. In addition, when scraping along the edges, no peripheral strip of coating must be left untouched, while at the same time the surrounding material should not be damaged. Again, this is almost impossible with the existing devices due to the shape of the blades. Therefore, an inexperienced user who tries to remove all of the coating along a window edge and/or in a corner is very likely to scratch or damage the window frame unless he is extremely cautious.
Also, it is important for the blade holder or the device to slide easily on the object to scrape, without scratching the flat surface or the surroundings. Existing devices are based on the assumption that the device will slide nicely provided that it features substantially flat “interior” surfaces. While the surface to be cleaned is usually flat, even and smooth, this is not necessarily true for the surrounding surfaces, such as a window frame. And, if the user pushes the scraper against the object or leans on it to increase the force applied in addition to pushing it forward, the surfaces could be scratched especially if something is caught between them and the device.
The blade used for such scraping applications typically has a very sharp edge and is therefore dangerous when handled by the user. These blades cause safety issues when the scraper is not stored safely as soon as it is collected from the storage and also every time the blade needs to be replaced. The latter situation is critical, since the blade has to be manipulated directly. The user has to be very careful to avoid getting injured, which can be a problem for the occasional user since he may not have the required skill to perform this manipulation safely. Concerning the storage of the scraper, for some existing devices, the blade can be retracted into a housing, or placed in a sheath or its edge is covered by a guard when it is stored. While in this way, the hazard the blade represents is removed, it does require additional manipulations or extra parts need to be kept with the device.
A first object of the present invention is to facilitate the scraping of the coating from flat surfaces in areas that are difficult to access. This is achieved by using a specific shape of the blade holder and of the blade holder, which is oriented according to the requirement of the invention.
A second object of the present invention is to improve the contact surfaces between the scraper and the object by enabling the scraper to slide more easily on the object and preventing the object surfaces from being damaged.
A third object of the present invention is to prevent the user from getting injured by removing the need of manually handling sharp blades and by providing a means of automatically guarding the sharp edge when the tool is not being used.
Preferred embodiments of the surface scraper tool are described according to the drawings. These preferred embodiments are to be understood as exemplary embodiments and any detailed description shall not be interpreted as limiting. In particular, the present surface scraper tool may be used for any purpose, be it for scratching, scraping or propelling fluids on any kind of surface. Alternate embodiments obvious to one skilled in the art will not be described in detail or will be omitted to prevent the relevant details of the invention to be overlooked.
The surface scraper tool is aimed at scraping a substantially smooth and flat surface of an object whose coating is to be removed. For example, the object may be a window pane or a wooden surface covered by paint, stickers or other types of coatings.
The surface scraper tool comprises a blade 1 and a blade holder 2 (
In order to reach the maximum scraping efficiency, i.e. the most efficient transmission of the user's force to the interface between the coating and the substrate, the blade should at a specific scraping angle β with respect to the surface 31. A too small scraping angle β can prevent the blade from cutting through the coating and separating it from the object to scrape 3 whereas a too large scraping angle β results in the coating being pushed forward rather than lifted from the surface, which requires a much stronger force. The scraping angle β is an acute angle which is often between 5 and 45 degrees. The ideal angle depends on the type of coating and the type of object to scrape. Best results are obtained if the scraping angle is between 15 to 25 degrees.
When scraping along surrounding parts 32 which shouldn't be scratched, e.g. a window frame, it is important to prevent the blade 1 from touching or bumping into it (
As a further improvement, the sharp edge 11 of the surface scraper tool forms an angle γ with respect to the guide plane as seen in the top view of
In one configuration, the sharp edge 11 removes the material present on the surface of the object 3 in the immediate vicinity of the guide plane. While this may be desirable for a clean scraping along the surroundings 32, there are cases where the scraping should leave a peripheral strip of material untouched. For example, windows can be embedded into the frame with a peripheral strip of glazing putty 5, as shown
In order to improve the contact between the surface scraper tool and the object to scrape 3, the bottom face 21 of the blade holder 2 can be made of or coated with a material that slides easily on a surface such as glass and doesn't scratch the object 3 during the scraping. For example, a polymer with low hardness can be used which does not scratch an object 3 made of glass or wood. In addition, the bottom face 21 may feature longitudinal creases or grooves, which have two advantages. First, the contact surface between the blade holder 2 and the object to scrape 3 is limited to the ridges of the grooves. Thanks to this reduced contact surface the smaller friction force allows the surface scraper tool to slide more easily on the surface. Second, an object featuring grooves has a lower friction coefficient in the direction of the creases than in the direction perpendicular to the creases, which makes it more likely that the surface scraper tool is moved parallel to the grooves and correspondingly the surrounding window frame. This improves the stability of the surface scraper tool and makes it easier to guide.
As can be seen from
Alternatively, the surface scraper tool may only comprise a single blade 1 and two symmetrically arranged bottom surfaces 21, 21′ forming the same scraping angle β with the blade 1. Thus, the blade tip 13 can be located on the left side of the scraper when the bottom face 21 is in contact with the object to scrape 3, or on the right side in case the bottom face 21′ is in contact with the object 3.
Often the object to be scraped 3, such as a ceiling or a high window is not located where it can be reached easily. Thus, using a ladder may be required. In these situations, the user may only have one hand to hold the scraper tool, because the other hand is used for holding himself on the ladder or supporting himself in another manner. When exerting a force on the surface scraper tool, it may be difficult to keep balance and the tool or, even worse, the user himself may fall. Therefore, it is important that the scraper tool is safe and the user is protected in the best possible way. This is achieved by providing the surface scraper tool with a blade guard 7. This blade guard 7 can be arranged on the surface scraper tool in a manner covering the cutting edge 11 of the blade 1 entirely, and removed prior to use (
In a further embodiment, the blade guard 7 may pivot vertically around the blade holder 2: up into the open position and down into the protected position (
In some environments use of a ladder for is limited such as in a stairwell or the window to be scraped is located horizontally in a location that is hard to reach. In such cases the blade holder 2 may comprise a means 23 for securing an additional handle 4, e.g. a pole (
This description and the accompanying drawings show exemplary embodiments of the invention. The invention, however, should not be interpreted as being limited to these particular embodiments. Variations of the embodiments can be made by those skilled in the art without departing from the scope of this invention as defined by the claims.
