GB2328170A - Hand-held machine tool for grinding, polishing and brushing - Google Patents

Abstract

A hand-held machine tool (14) for grinding, polishing and brushing, having a rotary tool (6) is comprises a machine housing (1) formed from a first, longer and a second, shorter housing shell (2, 3). The first housing shell (2) forming a flat shank (17) which extends along the axis (X-X) of the machine housing, protrudes forwards compared with the shorter housing half-shell (3) and carries a first toothed belt wheel (24) engaging in a rotation-proof manner round a tool shaft (19), and a toothed belt (25) which is wrapped around the said toothed belt wheel and is coupled to another toothed belt wheel (26). Vacuum suction apparatus is built into the tool for removing grinding debris.

Description

1 2328170 1 Hand-held machine tool for gdnding. polishing and brushing

Prior art

The invention relates to a hand-held machine tool for grinding, polishing and brushing, 'm accordance with the pre-characterising clause of claim 1.

A wall groove milling machine, mi which a gear unit housmig, which receives an angular gear unit and a reduction gear unit adjacent thereto, is flanged onto a housing surrounding an electric motor, is known through DE-C 644 011.

The gear unit housing has a slot which is open towards the front and in which a groove-milling disc is mounted 'm a driveable manner. The groovemilling disc is carried by a tool shaft which passes through the slot and the ends of which are mounted, on both sides of the slot, in the forkshaped ends of the gear unit housing. The shanks of the fork of the gear unit housing, which are formed on both sides of the slot, are relatively thick and wide, that is to say at least as wide as the transition aperture or slot for receiving the groove-milling disc. As a result, this machine is limited to the use of relatively narrow groove-milling discs.

Furthermore, the known wall groove milling puttet has a complitated dust extraction arrangement which works as a negative; -pressure pump, is operated via the motor-coofing air and is designed in a manner.,costly innaterial and low in efficiency.

A hand-held belt grinding machine has also been proposed, the driving roller of which is mounted, preferably in conjunction with tensioning rollers for the grinding belt so as to be laterally supported by only one end on a mounting plate.

2 As a result, grinding in a manner flush with an edge is possible on the side opposite the mounting plate, but the use of brushes, polishing rollers and grinding rollers is not possible with this machine.

This hand-held gninding machine has an efficient extraction air guidance system, the orifice of which is disposed closely adjacent to the periphery of the driving roller.

Advantages of the invention The hand-held machine tool according to the invention having the characterising features in claim 1 avoids the disadvantages of the prior art. It guarantees convenient and rapid changing of the tools and the use of tools with almost any desired, practically usable geometry. That affects both the length and width and also the contour of the tools.

The tool may be a cylindrical roller or a conical one or a disc, under which circumstances both the peripheries of the roller or disc and also their circular end faces may serve as working faces. These rotary tools of differing width and contour can be interchangeably fastened on a smigle shaft in a central and rotationally rigid manner. For the purpose of changing tools, there is no need to first remove the shank of a fork before the rotary tool can be taken off the tool shaft, while the omission of a fork shank from the design makes it possible to machine workpieces in an unrestricted manner flush with the rim or edge thereof, by means of the hand-held machine tool.

It is advantageous that the rotary tool has a shell-shaped protective housing engaging round it radially over Its entire width, under which circumstances the 11 workpiece can be exposed to greater or lesser degrees by means of the protective housin& which is similar to a swinging protective hood in hand- held circular saws.

If the rotary tool is a disc with a circular or front-end working face, the protective housing may either protrude axially beyond the working face in an elastic manner, in which case it can be retracted behind the working face when machining workpieces, or else it may completely mask the working face as a flat part. The protective housing may also to a great extent mask the shank side, and the side opposite the latter, in an elastically compliant manner.

It is particularly favourable if the protective housing consists of two half-shells which can be pivoted towards one another, essentially about the axis of rotation of the rotary tool. With the aid of the half-shells (wide circular ring segments) which can be swivelled towards one another, uniform contact pressure or abrasion on the workpiece to be machined can be achieved. Instead of the half-shells that can be pivoted in opposite directions, it is also possible to use a single half-shell after the fashion of a blind.

It is particularly advantageous that use may be made of essential motor housing and gear unit housing elements of a bar-shaped belt grinder, in which case extraction begins in the immediate proximity of the periphery of the rotary tool and takes place over a short path parallel with the machine housing.

Drawings An exemplified embodiment of the invention constructed as a roller grinder will be explained 'm greater detail with the aid of the diagrammatic drawings.

4 Figure 1 shows a side view of the roller grinder according to the invention, and figure 2 shows a longitudinal section containing the longitudinal axis of the roller grinder according to figure 1.

Descn"ption of the exemplified embodiment Figure 1 shows the side view of a roller grinder 14 which has an elongated machine housing 1 which serves as a handle and merges, at the front, into a region which serves as the gear unit housing and is immediately adjacent to the grinding roller 6.

The machine housing 1 consists of housing shell halves 2, 3, which are joined to one another in a centrally circumferential joint 4 (figure 2), the housing shell 2 being longer than the housing shell 3.

The grinding roller 6 disposed at the front end of the roller gTinder 100 is mounted for rotation about an axis Y-Y extending at right angles to the longitudinal axis XX (figure 2). Swinging protective shells 7, 8 are pivotable about the said axis Y-Y in an elastically resetting manner.

At its rear end 9, the machine housing 1 carries the extraction union 11 of an extraction duct 11 ", the front end of which is an extraction orifice 11' which is moulded into the housing shell 3. The extraction hose, not represented, of a dustextractor, or else a dust bag, can be fastened to the extraction union 11.

Next to, and parallel with the extraction union 11, there passes out of the machine housing 1 an electric cable 10 for supplying current to the electric motor 32, which is supplied with cooling air via ventilation slots 12 likewise disposed in the rear region of the machine housing 1.

The swinging protective shells 7, 8 engage round the grinding roller 6 at a radially small interval over about three quarters of the periphery and can be completely pivoted back, particularly independently of one another, being mounted on the machine housing 1 so as to be pivotable in opposite directions which are indicated by a double arrow. Located on the machine housing 1 mi the proximity of the front end 5 in the region of the gear unit is a threaded bore 13 for a handgrip, not represented, which can be screwed in and which facilitates two-handed operation of the roller grinder 14 when in use.

In the central part of the machine housing 1 there can be perceived an electric on/off switch 15 which can be operated particularly successfully with the thumb when the right hand engages round the said machine housing 1 from above. A rotational speed switch 16 additionally disposed in the proximity of the rear end 9 of the machine housing 1 is likewise disposed in an ergonomically favourable manner.

On the housing shell 2 side, the front end 5 of the machine housing 1 has a slender, hollow shank 17 which protrudes forwards, compared with the housing shell 3.

Flanged onto that side of the shank 17 which faces towards the housing shell 3 is a bearing body 18 for receivmig a tool shaft 19, which bearing body seals off the machine housing 1 in a dust-tight manner on the same side as the longer housing shell 2.

6 Bearings 20, 2 1, which engage round the tool shaft 19, are disposed in the bearing body 18 at an axial interval. The grinding roller 6 is disposed in a radially and axially locked manner on the free end of the tool shaft 19. Fastened on the tool shaft 19 in a rotation-proof manner on the opposite side of the bearing body 18 from the grinding roller 6, is a toothed belt wheel 24 which is coupled, via a toothed belt 25 guided in the helve 17, to another toothed belt wheel 26 aligning therewith. The other toothed belt wheel 26 is connected in a rotation-proof manner to an angular gear unit shaft 29 which is disposed, parallel with the axis of rotation of the tool shaft 19, in two rolling bearings 27, 28.

Engaging in a rotation-proof manner round the angular gear unit shaft 29, at a relatively small axial interval from the other toothed belt wheel 26, is a spur bevel wheel 30 which meshes with a spur pinion 30' and forms, with the latter, an angular gear unit 30". The spur bevel wheel 30 is constructed as a crown wheel and the spur pinion 30'as a spur gear. The spur pinion 30'is carried by a motor shaft 32' which is mounted in a rolling bearing 31 which is supported on the machine housing 1, approximately centrally between the gear unit region and the region of the electric motor 32.

By loosening and removing the nut 22 and the supporting washer 23 from the tool shaft 19, the cylindrical grinding roller 6 can be exchanged for another tool, for example a brush or the like.

When the swinging protective shells 7, 8 are swivelled towards one another in the direction of the double arrow 33, a machining aperture 34 of greater or lesser size can be produced 'm the direction of a workpiece, not represented, and aids not only the setting of a suitable grinding depth but also the protection of the person operating the roller grinder 14. the extraction of grinding dust through the 7 extraction orifice 1 l' being particularly efficient.

Continuous or step-wise adjustment for the inner and outer swinging protective shells 7 and 8 is represented by three different broken lines 7, 7, 7... and 8, 81t, 8PP1 in figure 1, which belong together.

The protective effect of the swinging protective shells 7, 8 is increased through the fact that the said swinging protective shells 7, 8 are drawn around the tool 6 on the side that faces towards the helve 17 and on the side that faces away from the latter, so that they at least partially cover the end or side faces of the tool 6. On that side which faces towards the orifice 1 l' of the extraction duct tP, the swinging protective shells 7, 8 carry transition apertures, not represented, for letting through air and dust.

Instead of the gears 24, 26 and of the toothed belt 19, use may also be made of other suitable transmission means.

8

Claims (1)

1. Claims

   1. Hand-held machine tool (14) for grinding, polishing and brushing, having a rotary tool (6) which is rotatably mountedat one end of a machine housing (1) containmig a motor (32) and an angular gear unit (30"), characterised in that the machine housing (1) is formed from a first, longer and a second, shorter housing shell (2, 3), the first housing shell (2) forming a flat shank (17) which extends along the axis (X-X) of the machine housing, protrudes forwards compared with the second, shorter housing half-shell (3) and carries a first toothed belt wheel (24) engaging in a rotation- proof manner round a tool shaft (19), and a toothed belt (25) which is wrapped around the said toothed belt wheel and is coupled to another toothed belt wheel (26).

   2. Hand-held machine tool according to claim 1, characterised in that, in the region of the shank (17), the first housinghalf-shell (2) is masked, on that side which faces towards the second housing shell (3), by a bearing body (18).

   3. Hand-held machine tool according to claim 2, characterised in that the contour of the machine housing (1) merges, at least approximately tangentially, into the contour of the roller-shaped tool (6).

   4. Hand-held machine tool according to claim 1, 2 or 3, characterised in that the other toothed belt wheel (26) is seated in a rotation-proof manner on an angular gear unit shaft (29) disposed parallel with the tool shaft (19) and at right angles to the axis (X-X) of the machine housing, while the tool shaft (19) can be connected M" a rotation-proof manner to a roller-like tool (6).

   9 5. Hand-held machine tool according to claim 4, characterised in that the second housing shell (3) carries, closely adjacent to the periphery of the tool (6), the orifice (1 V) of an extraction duct (1 P) which terminates in an extraction union (11), particularly at the rear, on the machine housing (1).

   6. Hand-held machine tool according to one of claims 1 to 5, characterised in that the tool (6) has, engaging radially round it, at least one swivellable swinging protective shell (7, 8) which is concentric with the axis (Y Y) of rotation of the tool, while a machining aperture (34), which is of variably adjustable size in relation to a workplece, can be exposed by means of the swinging protective shell (7, 8).

   7. Hand-held machine tool according to claim 6, characterised in that the said tool carries two swinging protective shells (7, 8), which are approximately semicircular in cross-sedion, in such a way as to engage round one another and to be swivellable towards one another.

   8. Hand-held machine tool according to claim 7, characterised in that the swinging protective shells (7, 8) are drawn, on the same side as the helve (17) and on the opposite side, at least partially round the end faces of the tool (6).

   9. Hand-held machine tool substantially as herein described with reference to the accompanying drawings.