Field of the Invention

The present invention concerns an apparatus for grinding/polishing or cleaning a surface, including at least one grinding unit, a motor, a screen and a handle with shaft and grip, where the grinding unit is a rotatable and preferably horizontally arranged grinding cylinder driven by the motor, and which in a cylinder surface is provided with a number of grinding elements, where the screen partly encloses the grinding unit, and where the handle is connected with the screen.

Background of the Invention

When e.g. an old or badly maintained wooden floor is to be brought in order, it is typically planed/ground off before being finished with oil or varnish. Moreover, there is a need for grinding/polishing surfaces of glass fibre or similar fibre reinforced composite surfaces in order to prepare these for surface treatment/coating. As examples can be mentioned wind turbine blades, boat hulls and boat decks.

Also, there is a need for grinding metal surfaces for preparing these for surface treatment/painting.

The apparatuses applied are typically floor planes/floor grinding machines with either a number of round plates with circular grinding wheels or a grinding cylinder. The grinding cylinder may have a surrounding grinding belt or grinding elements in the cylinder surface.

The prior art apparatuses are typically large and heavy apparatuses which cannot easily be lifted by one person, and the weight entails that they may be difficult to manoeuvre. Furthermore, these apparatuses are usually provided with height adjustable wheels, which is not an advantage as the grinding cylinders will not follow the contour of the underlying surface optimally. The distance between the grinding cylinder and the underlying surface will be determined by the contour of the underlying surface at the places where the wheels are running. Support wheels for the apparatus will furthermore frequently prevent grinding/polishing from being effected up to an adjoining wall/corner.

Also, a handle will be permanently connected to the grinding unit of the apparatus via a forked branch that constitutes an end part of the handle, and which has a branch member disposed at respective sides of the grinding unit. Such a design is known, for example, from WO 2006092138 from the same inventor. Such a design with a fork branch connected to each side plate also makes it difficult to grind/polish right up to an edge and into corners. The handle is fixed such that it only can extend to one side of the apparatus. This makes it difficult to lift the apparatus free or to perform difficult manoeuvres when the apparatus is used for grinding along walls and into a corner.

Moreover, there is a problem when cleaning surfaces in urban spaces where paving stones and asphalt may be contaminated, e.g. by chewing gum. Cleaning has hitherto been performed by large machines and by a combination of mechanical, chemical and/or thermal treatment. Due to the size of these machines, it has been difficult to perform cleaning of smaller surfaces and surfaces up to walls, kerbstones, benches and the like.

Object of the Invention

It is the object of the invention to indicate an apparatus using a horizontally arranged grinding cylinder, and which is easy to manoeuvre, particularly by grinding/polishing and cleaning surfaces along walls and into a corner, and which has a low self-weight. Moreover, it is the object to indicate an apparatus where it is possible to achieve a grinding/polishing and cleaning that will reach as far as possible into corners and at adjoining vertical faces, such as walls.

Description of the Invention

This is achieved by an apparatus of the kind specified in the introduction of claim 1, which is peculiar in that it includes a screen in the form of a side plate and a partly cylindric plate mounted thereon, which at its side is provided with an opening through which the grinding elements project, and which at its end opposite the side plate is closed by an end plate, that the motor and the grinding cylinder are mounted on the side plate, that the handle is mounted pivotably on the side plate about a central bearing with a central axis which is parallel with the central axis of the grinding cylinder, and that the handle is provided with fixing means that may engage corresponding fixing means on the side plate for retaining the handle in at least one upwardly and outwardly oblique position at each side of the apparatus.

The apparatus is light and mechanically simple and may grind largely right into corners as the handle is just pivoted between its two positions when grinding into a corner along a first wall and by grinding away from the corner along an adjoining sidewall. The grinding apparatus may go very close to a wall and into a corner as the side plate with all elements mounted faces away from the wall. It is thus only the end plate that separates the grinding elements from the wall. This has furthermore the advantage that there will be no risk of the grinding elements damaging skirting boards and walls.

Provided with special grinding elements, the apparatus is suited for cleaning surfaces in urban spaces, for example for removing chewing gum from paving stones and asphalt.

Moreover, the apparatus is suited for grinding/polishing profiled composite boards.

According to a preferred embodiment, the apparatus according to the invention is peculiar in that the handle has an angularly bent part such that the shaft of the handle extends in a vertical plane which is disposed largely at the middle of the apparatus. Hereby is achieved a symmetric design which is easy to manoeuvre.

According to a further embodiment, the apparatus according to the invention is peculiar in that the grip of the handle has a width which is less than the axial extension of the grinding cylinder in direction away from the side plate. The apparatus may hereby run very close to a wall as the grip will not limit the possibility of having the grinding cylinder running right up to a wall. According to a further embodiment, the apparatus according to the invention is peculiar in that the two positions of the handle are about 45° in relation to horizontal. In practice, this will provide the most suitable working position. However, the angle can be changed up to +/- 10°. Within such a range it will still be possible to get an ergonomic work position. This is particularly the case if the handle is longitudinally adjustable. Therefore, according to a further embodiment the invention is peculiar in that the shaft of the handle is longitudinally adjustable.

According to a further embodiment, the apparatus according to the invention is peculiar in that the fixing means of the handle is a spring-loaded pawl, and that the corresponding fixing means of the side plate are two holes for receiving the pawl which is pressed into the holes by the spring when the pawl is aligned with one of the holes. Hereby, easy operation is obtained as a user after running along a wall into a corner only needs to pull out the pawl against the action of the spring and turn the apparatus towards the next wall, pivoting the handle to the opposite position, where it is automatically locked since the spring moves the pawl into the hole.

According to a further embodiment, the apparatus according to the invention is peculiar in that the handle is pivotably suspended by a bearing spaced apart from the end of the handle farthest from the grip of the handle, and that the fixing means of the handle is disposed closer to this end. Hereby, the extreme end of the handle may be placed at the outer part of the screen, close to the open bottom of the cylindric screen. This facilitates manoeuvring. According to a further embodiment, the apparatus according to the invention is peculiar in that the grinding elements are replaceable as they are mounted in axially extending grooves in the cylinder surface. The screen may thus just be dismounted from the side plate, and the grinding elements may then readily be replaced when they are worn, or when the apparatus is to be provided with another type of grinding elements.

According to a further embodiment, the apparatus according to the invention is peculiar in that the grinding elements extend from the side plate to the end plate of the screen. Hereby is ensured that the apparatus may grind closely up to a wall as only the thickness of the end plate will be decisive for the part of the surface which cannot be ground/polished. According to a further embodiment, the apparatus according to the invention is peculiar in that the motor is disposed vertically above the grinding cylinder, and that the motor drives the grinding cylinder via a belt drive. This provides a very good weight distribution, making it possible to produce the apparatus with a very low weight. In practice it has appeared possible to achieve apparatuses with a weight of 12-15 kg for apparatuses with grinding cylinders with a diameter of 300 mm and a length of 200 mm.

According to a further embodiment, the apparatus according to the invention is peculiar in that the grinding elements include sandpaper items which are preferably slit from their outer edge and inwardly towards the cylinder surface, and which have grain size from 36 to 60. Hereby is achieved an apparatus which is particularly suited for use by cleaning surfaces of paving stones and asphalt, e.g. for removing chewing gum. The sandpaper items and the grinding cylinders may be of a type marketed by the company Flex Trim A/S, Glyng0re, Denmark.

Moreover, the invention concerns a use of the apparatus for cleaning surfaces, e.g. in urban spaces, for removing chewing gum from paving stones and asphalt.

Description of the Drawing

In the following, the invention will be explained in more detail with reference to the enclosed drawing where:

Fig. 1 shows an apparatus according to the invention, seen from the side;

Fig. 2 shows the apparatus as seen from the end;

Fig. 3 shows a perspective view of the apparatus; and

Fig. 4 shows a perspective view of the apparatus with some parts removed. Detailed Description of Embodiments of the Invention

In the following, the apparatus will be described with reference to Figs. 1 - 4. In this description, there is given an explanation of the apparatus on the basis of a horizontal and vertical orientation. This refers to the orientation of the apparatus when in use for grinding/polishing floors.

The apparatus 1 is intended for grinding/polishing a surface. It includes a grinding unit 2, a motor 3, a screen 4 and a handle 5. The grinding unit 2 includes a rotatable horizontal grinding cylinder 6 driven by the motor 3 via a belt 7 which is in engagement with a pulley 8 on the motor and a pulley 9 on the grinding cylinder 6. In a cylinder surface 10, the grinding cylinder 6 is provided with a number of grinding elements 11 which are mounted exchangeable in axial grooves (not shown) in the cylinder surface 10.

The apparatus includes a side plate 12. The screen 4 and the motor 3 and the handle 5 are mounted on this side plate 12.

The screen 4 partially encloses the grinding unit 2, as it is formed by a partially cylindric plate 13 which at its side has an opening 14 through which the grinding elements 11 project. At its end opposite the side plate 12, the screen is closed by an end plate 15. The grinding elements 11 have a length so that they extend to the end plate 15. The handle 5 is mounted pivotably on the side plate 12 about a central bearing 16 which is disposed spaced apart from the end 26 of the handle, and which has a central axis 17 parallel with the central axis 18 of the grinding cylinder. The handle is provided with fixing means in the form of a spring-loaded pawl 19 which is located at the end 26 of the handle. The pawl 19 can be brought to engage corresponding fixing means in the side plate in the shape of two holes 20 for receiving the pawl 19, which is pressed into the holes 20 by the spring (not shown) when the pawl 19 is aligned with one of the holes 20. The holes 20 are located at the lower edge of the side plate 12 for easy manoeuvring. Retention of the handle 5 at a position 45° relative to horizontal and obliquely upwards and outwards at each side of the apparatus is hereby established.

The handle has an angularly bent part 21 such that the shaft 22 of the handle extends in a vertical plane 23 which is largely disposed at the middle of the apparatus. Furthermore, the grip 24 of the handle has a width which is less than the axial extension 25 of the grinding cylinder in direction away from the side plate 12. The shaft 22 of the handle includes an outer tube 28 and an inner tube 29 which are telescopingly adjustable for adapting the handle to users with different heights.

The motor 3 is located vertically above the grinding cylinder 6, and the motor 3 drives the grinding cylinder via a belt drive including belts 7 that are in engagement with the pulley 8 on the motor and the pulley 9 on the grinding cylinder. The belt drive is covered by a protective screen 27.