PROTECTIVE COVER FOR AN ELECTRIC GRINDING MACHINE

FIELD OF THE INVENTION

The invention concerns an electric grinding machine which is especially intended for deburring, i.e. grinding burrs of e.g. metal constructions etc.

BACKGROUND OF THE INVENTION

A protective cover for such a grinding machine is described in GB 1 577 286. The known cover has a tubular section that can be mounted on a hand tool by means of a protective clip. In addition a resilient insert, for example a rubber sleeve can be arranged in the bore of the tubular section to provide a damping element.

SUMMARY OF THE INVENTION

The present invention aims to present a grinding machine that has improved capabilities with respect to the exhaust efficiency of the particles which release during deburring and with respect to the ergonomics and manoeuvrability of the machine.

To that end the grinding machine comprising a motor part, a grinding disk, at least one connection part for connecting the grinding disk to the motor part, and an exhaust cover, which, in use, partially covers the grinding disk, according to the invention further comprises a flexible coupling between the connection part and the exhaust cover, which flexible coupling is arranged to enable the exhaust cover to move relative to the connection part.

As the exhaust cover is movable relative to the connection part, a substantial improvement is achieved in operational comfort and efficiency, as well as in exhaust efficiency, thanks to improved adaptation of the plane of the cover to the plane and/or shape of the construction to be deburred. This allows the grinding disk to be brought closer to the construction to be deburred. As the grinding disk can be

brought closer to the construction to be deburred, viz. with less hindrance of the cover thanks to its flexibility, a greater deburring efficiency can be obtained. An additional advantage of the flexibility of the exhaust cover relative to the connection part and the therewith reduced hindrance is that the exhaust cover can cover the grinding disk over a larger part of its circumference. This also enables an improved exhaust efficiency.

It is noted that the construction known from the cited document does not disclose nor suggest that the cover is movable. The rubber sleeve described in the cited document merely serves as a dampening element. In contrast to the present invention, the rubber sleeve that is clamped between the tubular section and the tool by a pipe-clip would prevent substantial movements between the cover and the disk.

It is further remarked that GB 2430638 A, published after the priority date of the present invention, describes a handheld power tool comprising a housing in which a motor is arranged for rotatingly driving a tool such as a cutting wheel. The tool has a protection cover. The protection cover is movable to compensate for vibrations. A grinding tool is not disclosed therein, nor is it disclosed therein that the cover has an exhaust function. The flexible interface between the machine's cover and bearing shaft is preferably arranged in a way that the cover is resiliently movable along the axis of the bearing shaft. This allows the cover to move back to its original position after the tool is removed from the object to be ground. Preferably, the flexible interface between the machine's cover and bearing shaft is, moreover, arranged in such way that the cover is pivotally movable around the axis of the bearing shaft. As will be clear from the accompanying figures, a preferred embodiment of the flexible interface comprises an O-ring of a flexible material between the cover and the bearing shaft, which O-ring may be made of a natural or synthetic rubber or elastomer. The flexible O-ring allows the cover to move resiliently along and relative to the axis. Alternatively other constructions within the scope of the claims are conceivable by the skilled person, such as a flexible interface comprising a helical spring.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention are described in more detail with reference to the drawings.

Figure 1 shows in first and a second perspective view a preferred embodiment of the grinding machine according to the invention,

Figure 2 shows a side elevation of said embodiment,

Figure 3A shows a cross-section of a part of the grinding machine according to said embodiment, in an unloaded state of the machine,

Figure 3B shows a cross-section of said part in a second state of the machine,

Figure 3C shows a cross-section of said part in a third state of the machine.

DETAILED DESCRIPTION OF EMBODIMENTS

Figure 1 shows a grinding machine according to a preferred embodiment of the invention, comprising a motor part 1, a square, block shaped transmission part 2, a drive spindle 10 (See Fig. 3A-3C), a connection part for mounting a grinding disk 3 to the drive spindle. The grinding machine may be provided with a detachable cover 5 which - when mounted on the bearing shaft 4 surrounding the drive spindle - partly covers the grinding disk 3 for personal safety and forms an exhaust nozzle which can be connected, via a connection part 6 with a exhaust system (not shown).

In Figure 1 the cover 5 comprises a tubular mounting part 7, the inside shape and dimensions of which are compatible with the outside shape and dimensions of the bearing shaft 4.

Between the bearing shaft 4 and the cover's mounting part 7 a flexible interface (also denoted as flexible coupling) is provided which is arranged in a way that the cover is movable with respect to said bearing shaft.

Figure 2 shows a side-elevation of the embodiment of the grinding machine of Figure 1. Parts therein corresponding to those in Figure 1 have the same reference number. Figure 2 shows schematically how the cover 5 may tilt away from a surface that is ground by the grinding disk 3.

In Figures 3A, 3B, 3C parts corresponding to those in Figures 1 and 2 have the same reference number. Figure 3A-3C show a cross-section of a part of the grinding machine in three different states of the cover 5.

As shown in more detail in Figure 3A, 3B and 3C, in the preferred embodiment the flexible interface is formed by an 0-ring 8 between the tubular mounting part 7 of the cover 5 and an outer surface of the bearing shaft 4, made of a natural or synthetic rubber or elastomer. The O-ring may be accommodated in a groove 4a in the outside of the bearing shaft 4. Moreover a (shallow) groove 9 at the inside of the mounting part 7 may be provided to prevent that the cover 5 may slide off from the bearing shaft 4.

The mounting part 7 can be clamped around the bearing shaft 4 by means of any kind of (releasable) clamp coupling (not shown).

As shown schematically in Figure 3B and 3C the grinding machine's cover 5 and bearing shaft are arranged movably relative to each other by means of the "interfacing" O-ring 8. Figure 3B shows in more detail that the cover 5 may be tilted with respect to the axis 10 of the bearing shaft 4. And Figure 3C shows that the cover 5 is movable along the axis 10 of the bearing shaft. Accordingly the cover 5 is movable with respect to the grinding disk 3, which in practice means a substantial improvement in operational comfort and efficiency, as well as in exhaust efficiency, thanks to improved adaptation of the plane of the cover 5 to the plane and/or shape of the construction to be deburred. As the grinding disk 3 can be brought closer to the construction to be deburred, viz. with less hindrance of the cover 5 thanks to its flexibility, a greater deburring efficiency can be obtained.

Besides, the comfort and efficiency is additionally improved thanks to the ability provided by the configuration discussed here that, moreover, the mounting part 7 of

the cover 5 is pivotal around the axis 10 of the bearing shaft 4 which is additionally enabled by the flexible O-ring interface 8 between the mounting part 7 and the bearing shaft 4.