GB2429181A

GB2429181A - Hand-held grinding tool with illumination means

Info

Publication number: GB2429181A
Application number: GB0616291A
Authority: GB
Inventors: Karla Guertler
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2005-08-19
Filing date: 2006-08-16
Publication date: 2007-02-21
Anticipated expiration: 2026-08-16
Also published as: CN1915594A; GB2429181B; GB0616291D0; DE102005039291A1

Abstract

A hand-held grinding tool comprises a casing 11 which contains a motor 22 and a drive shaft24. The drive shaft 24 entrains a grinding disc 14. An illuminating device 30 for lighting a working area is disposed on or in a front region 18 of the casing 11. The tool is preferably a delta sander with the illuminating device 30 disposed above the front point of the grinding platen and inclined obliquely forwards and downwards. The illuminating device 30 may be electrically connected via a printed circuit board to a current source which drives the motor, or be powered by current induced in a coil 27 by a magnet 28 driven by the drive shaft 24 to rotate in the coil 27 or powered by a mains unit. The illuminating device 30 may be one or more leds, e.g. disposed in a row, arc or ring.

Description

R.312275 27. 07. 2005 ROBERT BOSCH GMBH, 70442 Stuttgart Hand-held

grinding machine

Prior art

The starting point of the invention is a hand-held grinding machine of the kind defined in the pre-characterising clause of Claim 1.

A hand-held grinding machine of this type is known, for example, which is designed as an eccentric grinder (DE 101 48 339 Al) . The carrying-out of grinding operations with the aid of hand- held grinding machines of this type demands skill and precision in order to avoid damage and achieve a satisfactory result, grinding-wise. This applies, above all, to those hand-held grinding machines which are constructed as grinders that negotiate edges and corners, for example to ones having approximately triangular grinding discs, or to triangular grinders; because particular vigilance is necessary, precisely when carrying out grinding operations in corners and on edges.

Advantages of the invention The hand-held grinding machine having the features in Claim 1 meets these requirements; because the working area is satisfactorily illuminated through the fact that an illuminating device is provided in the front region of the casing. Thus, for the purpose of carrying out grinding operations in corners or on edges or at other points where visibility is poor, sufficient light is available to achieve an accurate result, grinding-wise, without the risk of damaging adjoining components. The working area is S satisfactorily illuminated by means of the illuminating device, even when working against incident light. The workstation-illuminating system integrated into the hand- held grinding machine results not only in advantages in the case of standard grinding operations but, in addition, in the advantage of accurate grinding even in corners and on edges, under projections or cappings, while avoiding breaks in grinding, it being possible to obtain even clean grinding of transitional portions. The hand-held grinding machine can be brought up to edges and the grinding disc oriented appropriately at this point with illumination, under which circumstances any risk of damage to adjoining faces, for example proud-standing lateral faces, is eliminated. It is also advantageous that the operator is able to clearly observe, and ascertain in good time, the state of the abrasive disc, for example the degree of wear of its edge. The removal or extraction of grinding dust can also be carried out in a targeted manner by means of this hand-held grinding machine, as a result of said dust being clearly discernible. Possible operating errors are avoided, since possible incorrect operations during the grinding process are immediately detectable as a result of the illumination by means of the illuminating device. This illumination makes it possible to carry out grinding with triangular rubbing plates, and even with grinding blades, right into the deepest recess. It is even possible to grind concave or convex shapes with the aid of an oval grinding blade. If the illuminating device has at least one light-emitting diode (LED), the particular advantages of the latter are utilised, namely robustness and insensitivity to vibration, low heat build-up, a long working life and also its rniniaturised design.

Advantageous further developments of, and improvements to, the hand-held grinding machine indicated in Claim 1 are possible by means of the features set out in the other claims.

Drawings The invention is explained in greater detail below with the aid of exemplified embodiments represented in the drawings, in which: Fig. 1 shows a diagrammatic view, in perspective, of a hand-held grinding machine according to a first exemplified embodiment; and Fig. 2 shows a diagrammatic side view, partly cut away, of a hand-held grinding machine according to a second exemplified embodiment.

Description of the exemplified embodiment

Represented diagrammatically in Fig. 1 is an electrically powered tool in the form of a hand-held grinding machine 10 which has a casing 11 whose upper, elongated region 12 is shaped like a handle and has an electrical switch 13 at the front end. In this form of embodiment, the hand-held grinding machine 10 is constructed as a grinder that negotiates edges and corners and has, on its underside, an approximately triangular grinding disc 14. Said grinding disc 14 carries, for example on a supporting plate 9, an intermediate plate 15 whose underside is provided with a burr-type layer 16 for fastening an abrasive disc, of which nothing further is shown, in a detachable manner. The lower region 17 of the casing 11 is also approximately triangular in contour, in a manner adapted to the shape of the approximately triangular grinding disc 14, and has, in the front region 18 and above a front point 19 or corner of said grinding disc 14, a corresponding front point 20 or corner which merges into the upper region 12, for example via a concave arched portion 21.

The casing 11 receives a motor, of which nothing further is shown, having a gear unit and a drive shaft which entrains the grinding disc 14 in an oscillating manner. Said casing 11 also contains a current source, likewise not shown, particularly in the form of a lithium/ion storage battery, which serves to supply the motor with current.

Hand-held grinding machines 10 of this type, which are fed via a storage battery, are widely known.

In the case of this hand-held grinding machine 10, the special feature lies in the fact that an illuminating device 30, which serves to illuminate the working area of said hand-held grinding machine 10, is disposed in the front region 18, for example the arched portion 21, of the casing 11. Said illuminating device 30 is disposed on or in the casing 11 and, in this case, above the grinding disc 14, in particular above the front point 19 or corner of the latter and, more precisely, in a manner inclined obliquely forwards and downwards, so that the working area located in front of said point 19 and close to it at the sides is illuminated in a particularly satisfactory manner. It is of particular advantage if the illuminating device 30 is fed by the same current source which also serves to supply the motor with current. Said hand-held grinding machine 10 is then particularly simple, compact, light and costeffective. In this case, the illuminating device 30 is connected, by means of electric leads which are not shown, to a printed circuit board which is contained in the casing 11 but of which nothing further is shown and which is located at the rear end of the hand-held grinding machine 10, which rear end is on the right in Fig. 1.

Electric leads lead from the said printed circuit board to the front region 18 and to the illuminating device 30 in said region.

In a particularly advantageous manner, the illuminating device 30 has at least one light-emitting diode (LED) 31.

This at least one light-emitting diode 31 consists, in advantageous manner, of a super-bright, white light- emitting diode with an angle of radiation which, although it is specific to the appliance according to the distance from the working surface, may nevertheless lie within the range from, for example, about 300 to 90 in the case of the present hand-held grinding machine 10. It has become apparent that a light-emitting diode 31, in particular, is especially well suited to the hand-held grinding machine 10 shown, which has a battery-fed motor; since in this case, because of the lithium/ion storage battery which is present, the small voltage needed for light-emitting diodes, which usually lies between 5V and l5V, is present as the output voltage of said storage battery.

Even though only one light-emitting diode 31 is indicated in the example in Fig. 1, it is nevertheless obvious that it is also possible to provide, at this point, a number of light-emitting diodes (LED's) which are disposed there, for example in a row and/or in an arc, for example in the form of a ring. In these cases, the light-emitting diodes are inserted, for example, in a holding strip made of plastic, for example, and are mounted on the hand-held grinding machine 10 in a suitable manner.

Light-emitting diodes 31 as the illuminating device 30 have various advantages, for example robustness and insensitivity to vibration, low heat build-up, a long working life and also their miniaturised design.

A hand-held grinding machine 10 of this kind provided with an illuminating device 30 has various advantages. By means of said illuminating device 30, it is possible to illuminate, in a very satisfactory manner, the working surface which is to be processed by means of said hand-held grinding machine 10. When grinding in corners and on edges or at other points where visibility is poor, an adequate amount of light for such points is generated by means of the illuminating device 30, so that the grinding tasks can be carried out in an accurate manner when grinding in corners and on edges. Even in the case of grinding operations in, for example, the area of a window frame against incident daylight and with a major light/dark difference, as a result of which the view of the working surface is otherwise reduced, accurate and easy grinding is possible because of satisfactory illumination by means of the illuminating device 30. Even in the case of grinding operations under projections, cappings, for example laminations, or the like, the illuminating device 30 delivers sufficient light, so that it is possible to carry out even these grinding operations in a precise manner. By means of the illuminating device 30, very precise working is also possible, for example grinding which is precise at specific points, the clean grinding of transitional portions while avoiding breaks in grinding or the like.

The illuminating device 30 allows the user of the hand-held grinding machine 10 a very good view of the field of work, for example a good view, in spite of the production of chips, of any markings or incipient cracklines, even if the latter should be at least partially covered by dust.

The risk of damaging proud-standing lateral faces when bringing the grinding disc 14 of the hand-held grinding machine 10 up to, or orienting it at, edges is also eliminated since, here too, there is satisfactory illumination by means of the illuminating device 30.

Furthermore, the degree of wear of the abrasive disc, for example of the edge of the latter, can be ascertained in good time by observing the progress of work under illumination. It is also advantageous that the extraction of grinding dust can be carried out in a targeted manner because of the satisfactory illumination. The illumination of the working area by means of the illuminating device 30 makes any operating errors during the grinding process immediately visible, and permits not only standard grinding operations with very good results, but also grinding with the aid of the grinding blade right into the deepest recess as well as the grinding of concave or convex shapes with the aid of the oval grinding blade.

In the second exemplified embodiment, which is shown in Fig. 2, the same reference numerals are used for those parts which correspond to the first exemplified embodiment, so that the reader is thereby referred to the description of the first exemplified embodiment in order to avoid repetitions.

The hand-held grinding machine 10 shown in Fig. 2 is constructed as a triangular grinder with an approximately triangular grinding disc 14. The casing 11 contains a motor 22 which drives, via a gear unit 23, a drive shaft 24 which is provided with a compensating weight 25 and, by its end which is the lower end in Fig. 2, entrains the grinding disc 14 in an oscillating manner. An illuminating device 30 for illuminating the working area is provided in the front region 18 of the casing 11 and has at least one light-emitting diode (LED) 31 which is held in said casing 11 in a replaceable manner and is disposed so as to be inclined obliquely forwards and downwards. The preceding remarks in connection with Fig. 1 also apply to the disposition of this illuminating device 30 and its special features, in particular the advantages which are achieved by means of it.

In the second exemplified embodiment in Fig. 2, the illuminating device 30 is fed, not by the current source which serves to feed the motor 22, but by a current source 26 of its own. Said current source has a magnet 28 which revolves within a coil 27 and is driven by the drive shaft 24 and by means of which an electric current for supplying the illuminating device 30 can be induced in the coil 27. Said coil 27 is electrically connected to the illuminating device 30, in particular to the at least one light-emitting diode 31, by means of electric leads 29.

This current source 26 is simple, space-saving, light and cost-effective. When the drive shaft 24 revolves, the magnet 28 rotates with it, as a result of which there is induced, in the coil 27, an electric current which is sufficient to light up the illuminating device 30, in particular the at least one light-emitting diode 31.

Whenever the motor 22 is switched on, the illuminating device 30 is also switched on at the same time.

In another exemplified embodiment of a hand-held grinding machine 10, which is operated by means of a mains voltage of 100 V to 240 V, a mains unit, which is accommodated in the casing 11 but takes up a corresponding amount of space therein, may serve as the current source for the illuminating device 30. By comparison with this, a mains unit, and its sometimes problematical accommodation in the casing 11, is superfluous in the case of the second exemplified embodiment shown in Fig. 2.

Claims

Claims 1. Hand-held grinding machine having a casing (11) which receives a

motor (22) having a drive shaft (24) which entrains a grinding disc (14) which receives an abrasive disc, characterised in that an illuminating device (30) for illuminating the working area is provided in a front region (18) of the casing (11)
2. Hand-held grinding machine according to Claim 1, characterised in that the illuminating device (3D) is disposed on or in the casing (11)
3. Hand-held grinding machine according to Claim 1 or 2, characterised in that the illuminating device (30) is disposed above the grinding disc (14) , in particular above a front point (19) or corner of the latter.
4. Hand-held grinding machine according to one of Claims 1 to 3, characterised in that the illuminating device (30) is disposed in a manner inclined obliquely forwards arid downwards.
5. Hand-held grinding machine according to one of Claims 1 to 4, characterised in that the illuminating device (30) is fed by a current source which serves to supply current to the motor (22) , in particular a lithium/ion storage battery.
6. Hand-held grinding machine according to Claim 5, characterised in that the illuminating device (30) is connected, for current-supplying purposes, to a printed circuit board in the casing (11) by means of electric leads.
7. Hand-held grinding machine according to one of Claims 1 to 4, characterised in that the illuminating device (30) is fed by a current source (26) of its own.
8. Hand-held grinding machine according to Claim 7, characterised in that the current source (26) consists of a mains unit or has a magnet (28) which revolves within a coil (27) and is driven by the drive shaft (24) and by means of which an electric current for current-supplying purposes can be induced in said coil (27)
9. Hand-held grinding machine according to one of Claims 1 to 8, characterised in that the illuminating device (30) has at least one light- emitting diode (LED) (31)
10. Hand-held grinding machine according to Claim 9, characterised in that the at least one light-emitting diode (LED) (31) consists of a super- bright, white light-emitting diode (31), and preferably, that the angle of radiation of the at least one light-emitting diode (31) lies within the range from about 30 to 90 .
11. Hand-held grinding machine according to Claim 9 or 10, characterised in that a number of light-emitting diodes (31) are provided, which are disposed in a row and/or in an arc, for example in the shape of a ring.
12. Hand-held grinding machine according to one of Claims 1 to 11, characterised by its construction in the form of a grinder that negotiates edges and corners, in particular a triangular grinder with an approximately triangular grinding disc (14).
13. A hand-held grinding machine substantially as herein described with reference to the accompanying drawings.