GB2444160A

GB2444160A - Auxiliary handle for a hand held machine tool with rapid adjustment by means of two threads

Info

Publication number: GB2444160A
Application number: GB0722825A
Authority: GB
Inventors: Gerhard Meixner; Uwe Engelfried; Jan Koalick; Lars Schmid; Johannes Schnitzler
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2006-11-24
Filing date: 2007-11-21
Publication date: 2008-05-28
Anticipated expiration: 2027-11-21
Also published as: DE102006055516A1; GB2444160B; GB0722825D0; CN101186034B; CN101186034A

Abstract

A supplementary handle for a handheld machine tool comprising a clamping collar 4 for clamping the supplementary handle 2 on part of the machine tool; a stirrup-shaped handle 6 for grasping and holding the supplementary handle 2; a lockable swivel joint 8 which is disposed between the clamping collar 4 and the stirrup-shaped handle 6; and a rotational actuating component 12 which serves to lock the swivel joint 8 and draw together the clamping collar 4, or to release the locked swivel joint 8 and loosen the clamping collar 4, and which can be brought into threaded engagement with an external thread 35 on a tensioning screw 28 which passes through the swivel joint 8. The actuating component 12 comprises a threaded nut 64 which has an internal thread 70 for threaded engagement with the external thread 35 on the tensioning screw 28 and is in threaded engagement, via an external thread 66, with an internal thread 62 in a grip-type part 54 of the actuating component 12.

Description

1 2444160

Description Title

Supplementary handle for a hand-held machine tool, with rapid adjustment by means of two threads The invention relates to a supplementary handle for a hand- held machine tool, in accordance with the pre-characterising cause of claim 1.

Prior art

From Figures 4 and 5 of DE 101 30 548 Al by the Applicant, a supplementary handle for a hand-held machine tool is already known, which is clamped to part of a hammer drill by means of a clamping collar and has a stirrup-shaped handle for grasping and holding the supplementary handle and also a swivel joint which is disposed between said clamping collar and said stirrup-shaped handle.

Furthermore, the Applicant already offers for sale and distributes supplementary handles of the type initially mentioned, in which the swivel joint can be locked with the aid of an actuating knob and a tensioning screw in order, on the one hand, to keep the stirrup-shaped handle, with respect to the clamping collar, in a desired rotational position with respect to the axis of swivelling of the swivel joint and, on the other hand, to keep said clamping collar in a desired rotational position with respect to the centre of a circle set by said clamping collar, or with respect to the machine tool. In said supplementary handles, the actuating knob has an internally threaded bore in which there engages one end, which is provided with an external thread, of the tensioning screw which, in turn, extends along the axis of swivelling of the swivel joint through receiving apertures, which are in alignment, in four hollow-cylindrical parts, which surround said axis of swivelling, of the joint of the supplementary handle. Of the four parts of the joint, the two outer parts are connected to the stirrup-shaped handle in a torsion-proof manner, while the two inner parts are connected to the clamping collar in a torsion-proof manner. By tightening the actuating knob, the adjacent inner and outer parts of the joint can be pressed against one another in pairs by their end faces which face towards one another. Those end faces which face towards one another of the four parts of the joint, which parts are manufactured from plastic by injection moulding, are provided with complementary toothing systems which are moulded into the plastic end faces of said parts of the joint. In order to prevent the toothing systems which engage in one another from deforming, after the actuating knob has been tightened, for example because of a major pressing force which is applied to the stirrup-shaped handle, something which might result, on the one hand, in wearing of the toothing systems and, on the other, in unintentional twisting of the stirrup- shaped handle about the axis of swivelling, the four toothing systems are of really coarse design, that is to say, their teeth each have a height of about 2.5 mm. Since, however, the two pairs of toothing systems which engage in one another must be moved apart by at least this tooth height in each case in order to adjust the stirrup-type handle, the actuating knob must cover an adjusting path of more than 5 nun before the stirrup-shaped handle can be tilted about the axis of swivelling with respect to the clamping collar. This corresponds to a number of revolutions of the actuating knob, something which is regarded by many workmen as consuming too much time and effort.

Adopting this as the starting point, the underlying object of the invention is to improve a supplementary handle of the type initially mentioned, to the effect that it can be adjusted more rapidly and easily.

Disclosure of the invention

This object is achieved, according to the invention, through the fact that the actuating component comprises a threaded nut which has an internal thread for threaded engagement with the external thread on the tensioning screw and is in threaded engagement, via an external thread, with an internal thread in a grip-type part of said actuating component.

By means of the combination of features according to the invention, the external thread on the tensioning screw and the internal thread in the threaded nut can be constructed as easy-running coarse threads which make it possible for the actuating component to approach the swivel joint easily and rapidly when said component is screwed up, while the external thread on the threaded nut and the internal thread in the grip-type part can be constructed as fine threads which make it possible to jam the swivel joint tightly for locking purposes when the actuating component is screwed tight with relatively little expenditure of force.

The internal thread in the threaded nut and the external thread on the tensioning screw preferably have a thread pitch which, on the one hand, is sufficiently coarse, so that the threaded nut moves over the external thread on the tensioning screw in an easy-running manner when the actuating component is screwed up but, on the other hand, is not too coarse, so that there still just occurs, between the two coarse threads which are in threaded engagement, automatic jamming which prevents the actuating component, which has not yet been screwed tight, from possibly falling off the supplementary handle.

The threaded nut is preferably screwed into a threaded bore in the grip-type part which is open towards the swivel joint, so that the threads on the tensioning screw, the threaded nut and the grip-type part are oriented coaxially with the axis of swivelling of the swivel joint when the tensioning screw extends through said swivel joint and the actuating component has been screwed onto said tensioning screw.

According to another advantageous development of the invention, in order to prevent the threaded nut from being screwed into, or out of, the threaded bore in an unwanted manner, there is disposed between said threaded nut and the grip-type part of the actuating component a torsion spring which preferably has a helically wound central part which is essentially coaxial with the axis of swivelling of the swivel joint and has an internal diameter which is larger than the external diameter of the external thread on the tensioning screw. In this way, said tensioning screw is able to penetrate into the interior of the torsion spring when the actuating component is screwed up, as a result of which the structural length, and thereby the length by which the actuating component projects beyond the adjacent end face of the swivel joint, can be made smaller.

In the non-tensioned state, the torsion spring holds the threaded nut in a position in which it projects slightly beyond an. end face of the grip-type part that faces towards the swivel joint, so that said threaded nut strikes, before the grip-type part, against an oppositely located stop face on the swivel joint when the actuating component approaches said swivel joint. In this state, as a result of the increasing frictional forces between its internal thread and the external thread on the tensioning screw, the threaded nut no longer continues to rotate, so that continuing rotation of the grip-type part leads to the latter twisting, with respect to the threaded nut, against the force of the torsion spring, until said grip-type part itself strikes against the stop face on the swivel joint in order to then jam the latter.

Like the known swivel joint, the swivel joint comprises at least one part of the joint which is connected to the clamping collar in a torsion-proof manner and at least one part which is connected to the stirrup-shaped handle in a torsion-proof manner, which parts of the joint can be rotated, with respect to one another, about an axis of swivelling of the swivel joint for the purpose of adjusting said stirrup-shaped handle. According to another preferred development of the invention, the locking or jamming of the swivel joint takes place through the fact that the parts of said joint are pressed against one another by a compressive force which is exerted by the grip-type part on an adjacent part of the joint after said grip-type part has struck against the stop face on the swivel joint, and also by a tractive force which is exerted by the threaded nut, via the tensioning screw, on a part of the joint at the opposite end face of said swivel joint.

Brief description of the dxawings

The invention will be explained in greater detail below with the aid of an exemplified embodiment which is represented in the drawings, in which: Fig. 1 shows a partially cutaway front view of a supplementary handle for a hand-held machine tool, with a clamping collar, a stirrup-shaped handle and an actuating knob for tightening said clamping collar and for locking a swivel joint between said clamping collar and said stirrup-shaped handle after said stirrup-shaped handle or supplementary handle has been adjusted; and Fig. 2 shows a partially cutaway, exploded front view of the supplementary handle which has been partially dismantled into its constituent parts.

Form of embodiment of tue invention The supplementary handle 2 represented in the drawings, which is intended for hand-held machine tools such as drilling machines, hammer drills or the like, comprises: a clamping collar 4 by means of which said supplementary handle 2 can be clamped to a cylindrical part (not represented) which is integral with the casing of said machine tools, for example to a cylindrical part of the shaft behind a tool-holding fixture in the case of drilling machines or hammer drills; a stirrup-shaped handle 6 with the aid of which said supplementary handle 2 can be grasped by an.operator; a lockable swivel joint 8 which is disposed between the clamping collar 4 and the stirrup-shaped handle 6-and by means of which the operator can set a desired swivelling position of the stirrup-shaped handle 6 about the axis of swivelling 10 of said swivel joint 8 with respect to said clamping collar 4; and an actuating knob 12 by means of which, on the one hand, the swivel joint 8 can be locked in a preset swivelling position and the clamping collar 4 can be drawn together on the cylindrical part of the machine tool in a preset rotational position, and by means of which, on the other hand, the locked swivel joint 8 can be released again and the clamping collar 4 loosened when the operator might wish to set a different swivelling position of the stirrup-shaped handle 6 and/or a different rotational position of the clamping collar 4.

As is most clearly represented in Figs. 1 and 2, the clamping collar 4 consists of a plastic moulding 14 which is manufactured in one piece by injection moulding and is in the shape of a ring which is open on one side and is provided, on its side that faces towards the stirrup-shaped handle 6, with a slit-type aperture 16. The width of said slit-type aperture 16 can be varied by means of the actuating knob 12 in order to draw the clamping collar 4 together for the purpose of fixing it in position on the hand-held machine tool while making its diameter smaller, or in order to slightly expand again the clamping collar 4 which is subjected to tension after being drawn together, in order to release or loosen it while enlarging its diameter.

The stirrup-shaped handle 6 consists essentially of a yoke part 20, which serves for grasping purposes and is essentially parallel to the axis of swivelling 10 of the swivel joint 8, and two side parts 22 and 24 which are rigidly connected to the yoke part 20 and are oriented essentially parallel to one another and which, together with the yoke part 20 and the swivel joint 8, enclose a gripping aperture 26 for the operator's hand which is placed around said yoke part 20.

As is most clearly represented in Fig. 2, the swivel joint 8 consists essentially of a tensioning screw 28 having an expanded head part 30 which is Constructed as a hexagon, a cylindrical shaft part 32, and a threaded part 34 which adjoins said shaft part 32 and has a coarse external thread 35, and also of three joint sleeves 36, 38, made of plastic which surround said tensioning screw 28 and of which the two outer joint sleeves 36 and 40 are disposed on opposite end faces of the swivel joint 8 and are connected in one piece to the adjacent side part, 22 and 24 respectively, of the stirrup-shaped handle 6, while an inner joint sleeve 38, which is divided in two by the slit-type aperture 16, is Constructed in one piece with the plastic part 14 of the clamping collar 4 and extends on either side of said Slit-type aperture 16 as far as the outer joint sleeve, 36 and 40 respectively, which is adjacent in each case.

In order, when the swivel joint 8 is locked, to prevent unintentional tilting of the stirrup-shaped handle 6 with respect to the clamping collar 4 as a result of a pressing force which is applied to the stirrup-shaped handle 6, the outwardly pointing end faces of the inner joint sleeve 38 and the adjacent, inwardly pointing end faces of the two outer joint sleeves 36 and 40 are provided with complementary toothing systems 42, 44. Said toothing systems 42, 44 consist, in each case, of a plurality of radial teeth which are constructed in one piece with the joint sleeves 38 and 36 and 40 respectively, and extend from cylindrical pass-through apertures 46, 48., 50 for the tensioning screw 28, which are in alignment, as far as cylindrical outer peripheral faces, which are likewise in alignment, on the joint sleeves 36, 38, 40, said teeth projecting axially beyond the end faces of the joint sleeves 36, 38, 40 in each case and being separated by complementary tooth spaces, so that said toothing systems 42, 44 are able to engage in one another essentially without any play if, in one of a plurality of discrete swivelling positions of the stirrup-shaped handle 6 with respect to the clamping collar 4, the teeth of the toothing systems 44 on the end faces of the outer joint sleeves 36, 40 come to rest above the tooth spaces in the toothing systems 42 on the adjacent end faces of the inner joint sleeve 38, and vice versa.

The expanded head part 30 of the tensioning screw 28 is received by a complementary blind hole 52, which serves as a twist-proofing device, in the joint sleeve 36, when said tensioning screw 28 is pushed, during the fitting of the supplementary handle, through the pass-through apertures 46, 48, 50 in the joint sleeves 36, 38, 40 by its shaft part 32 in the direction of the arrow A in Fig. 2, until the threaded part 34 projects outwards a little way beyond the joint sleeve 40 at the opposite end face of the swivel joint 8.

The actuating knob 12, which is manufactured from plastic by injection moulding, has a thickened grip-type part 54 which serves for grasping purposes and is provided with knurling (not represented) on the outer periphery and which encloses a threaded bore 60 which is in alignment with a central axis of the actuating knob 12 and has a fine internal thread 62 and which opens into a flat end face 58, which faces towards the swivel joint, on said grip-type part 54.

An essentially cylindrical threaded nut 64, which is provided, on its outer periphery, with a fine external thread 66 which is complementary to the fine internal thread 62 in the threaded bore 60, is screwed into said threaded bore 60. The threaded nut 64 itself encloses a threaded bore 68 which is coaxial with the central axis of the actuating knob 12 and has a coarse internal thread 70 which fits the coarse external thread 35 on the threaded part 34 of the tensioning screw 28. The thread pitch and the shape of the respective coarse threads 35 and 70 are selected in such a way that, for the purpose of fitting the actuating knob 12 on the supplementary handle 2, the threaded nut 64 can be screwed in an easy-running and rapid manner onto that threaded part 34 of the tensioning screw 28 which projects beyond the joint sleeve 40, but said threaded nut is held on the threaded part 35 with automatic jamming, in order to prevent undesired falling-off of said actuating knob 12.

The threaded nut 64 has a height which approximately corresponds to half the depth of the threaded bore 60, so that there is room for a torsion spring 76 between the bottom 72 of the threaded bore 60 and the oppositely located underside 74 of the threaded nut 64. The torsion spring 76, which is constructed as a helical spring, has a helically wound central part 78 beyond which a first end 80 of said helical spring, which end is bent over outwards and then upwards, projects in the upward direction and engages in an eccentric bore 82 in the underside 74 of the threaded nut 64. The opposite, second end 84 of the torsion spring 76 projects downwards and engages in an eccentric bore 86 in the bottom 72 of the threaded bore 60. The internal diameter of the central part 78 of the helical spring which is coaxial with the central axis of the actuating knob 12 is larger than the external diameter of the coarse thread 35 on the tensioning screw 28 so that, when the actuating knob 12 is screwed up, the threaded part 34 of said screw is able, after passing through the threaded bore 68 from the top, to penetrate into the aperture which is enclosed by the central part 78 of the torsion spring 76, as is represented in Fig. 1.

The depth of the threaded bore 60, the height of the threaded nut 64 and the length of the torsion spring 76 are coordinated with one another in such a way that the upper side 88 of the threaded nut 64 is approximately in alignment, when the torsion spring is relieved of tension, with the surrounding end face 58 of the grip-type part 54 of the actuating knob 12, while a flat collar 90, which is moulded onto the upper side 88 of the threaded nut 64 around the mouth of the threaded bore 68, projects slightly beyond the end face 58.

When the supplementary handle 2, which is represented in the dismantled state in Fig. 2, is assembled, the tensioning screw 28 is first of all slipped through the pass-through apertures 46, 46, 50, which are in alignment, in the threaded sleeves 36, 28, 40, until its head 30 is in the blind hole 52 and its threaded part 34 projects outwards beyond the joint sleeve 40. The actuating knob 12 is then screwed onto the projecting threaded part 34 of the tensioning screw 28 in the clockwise direction, by bringing the coarse external thread 35 on the projecting threaded part 34 of said tensioning screw 28 into threaded engagement with the coarse internal thread 70 in the threaded nut 64.

After the clamping collar 4 has been pushed onto the cylindrical part of the hand-held machine tool, said clamping collar 4 has been oriented in a desired rotational position, and a desired swivelling position of the stirrup-shaped handle 6 with respect to said clamping collar 4 has been set, the actuating knob 12 is rotated further in the clockwise direction in order to draw the clamping collar 4 together on the cylindrical part of the hand-held machine tool and to lock the swivel joint 8 in the preset swivelling position.

In the process, the actuating knob 12, together with the threaded nut 64, moves in an easy-running manner over the coarse thread 35 on the tensioning screw 28 until the collar 90 which projects beyond the threaded nut 64 strikes against a flat stop face 92 which surrounds the mouth of the pass-through aperture 50 on the oppositely located outer side of the joint sleeve 40. The two joint sleeves 36 and 40 are then moved up to one another by a compressive force exerted on the part 40 of the joint by the collar 90 and by a tractive force exerted on the part 36 of the joint by the head part 30 of the tensioning screw 28, the toothing systems 42 and 44 coming into engagement with one another first, before the three joint sleeves 36, 38, 40 are then pressed against one another and the clamping collar 4 is drawn together. At some point in time during this operation, the friction between the coarse threads 35 and 70 which are in engagement, and the friction between the collar 90 and the stop face 92, exceeds the torque transmitted by the handle-type part 54 to the threaded nut 64 via the fine threads 62 and 66 and via the torsion spring 76, whereupon the threaded nut 64 no longer continues to rotate. The torque which the operator continues to apply in the clockwise direction on the actuating knob 12 then has the consequence that said actuating knob 12 is now twisted, in relation to the threaded nut 64, along the two fine threads 62 and 66 and the collar 90 is lifted slightly off the stop face 92 until the end face 58 strikes against the latter, as is represented in Fig. 1. After the end face 58 has struck against the stop face 92, further rotation of the actuating knob 12 leads to the jamming of the joint sleeves 36, 38, 40 and to the final locking of the swivel joint 8.

For the purpose of readjusting the stirrup-shaped handle 6 or the clamping collar 4, the actuating knob 12 is undone anticlockwise, in the process of which it is first twisted, with respect to the threaded nut 64, along the threaded engagement of the fine threads 62 and 64, assisted by the force of the tensioned torsion spring 76, until the friction between the threaded nut 64 and the tensioning screw 28 has dropped to an extent such that said threaded nut can be twisted anticlockwise with respect to said tensioning screw. In addition, the torsion spring 76 ensures that the threaded nut 64 is reset into its starting position.

As a result of the measures described, the actuating knob 12 can, on the one hand, be moved rapidly and easily up to, and away from, the swivel joint 8 and, on the other hand, be screwed tight or unscrewed, with little expenditure of force on the part of the operator, for the purpose of respectively jamming or releasing the swivel joint.

Claims

Claims 1. Supplementary handle for a hand-held machine tool, having: a

clamping collar for clamping said supplementary handle on part of the machine tool; a stirrup-shaped handle for grasping and holding said supplementary handle; a lockable swivel joint which is disposed between said clamping collar and said stirrup-shaped handle; and a rotatable actuating component which serves to lock the swivel joint and draw together the clamping collar, or to release the locked swivel joint and loosen the clamping collar, and which can be brought into threaded engagement with an external thread on a tensioning screw which passes through said swivel joint, characterised in that the actuating component (12) comprises a threaded nut (64) which has an internal thread (70) for threaded engagement with the external thread (35) on the tensioning screw (28) and is in threaded engagement, via an external thread (66), with an internal thread (62) in a grip-type part (54) of said actuating component (12).
2. Supplementary handle according to claim 1, characterised in that the external thread (66) on the threaded nut (64) has a smaller thread pitch than the internal thread (70) in said threaded nut (64).
3. Supplementary handle according to claim 1 or 2, characterjsed in that the internal thread (70) in the threaded nut (64) and the external thread (35) on the tensioning screw (28) are in threaded engagement in an easy-running manner but with automatic jamming.
4. Supplementary handle according to one of the preceding claims, characterjsed in that the threaded nut (64) is screwed into a threaded bore (60) in the grip-type part (54), which bore is open towards the swivel joint (8).
5. Supplementary handle according to one of the preceding claims, characterised by a torsion spring (76) which is disposed between the threaded nut (64) and the grip-type part (54).
6. Supplementary handle according to claim 5, characterjsed in that the torsion spring (76) has a helically wound central part (78) which is essentially coaxial with the axis of swivelling (10) of the swivel joint (8) and the internal diameter of which is larger than an external diameter of the external thread (35) on the tensioning screw (28).
7. Supplementary handle according to claim 5 or 6, characterjsed in that two opposite ends (80, 84) of the torsion spring (76) are in engagement, at a distance from the axis of swivelling (10) of the swivel joint (8), with the threaded nut (64) and the grip-type part (54) respectively.
8. Supplementary handle according to one of claims 5 to characterised in that, when the tension spring (76) is relieved of tension, the threaded nut (64) projects slightly beyond an end face (58) of the grip-type part (54) that faces towards the swivel joint (8).
9. Supplementary handle according to claim 8, characterised in that, after striking against an oppositely located stop face (90) on the swivel joint (8), the threaded nut (64) is arrested and the grip-type part (54) is then rotated, in relation to the threaded nut (64), against the force of the torsion spring (76) -
10. Supplementary handle according to one of the preceding claims, characterised in that the swivel joint (8) comprises at least one part (38) which is connected to the clamping collar (4) in a torsion-proof manner and at least one part (36, 40) which is Connected to the stirrup-shaped handle (6) in a torsion-proof manner, which parts of the joint can be rotated, with respect to one another, about an axis of swivelling (10) of the swivel joint (8) for the purpose of adjusting said stirrup-shaped handle (6) and can be pressed against one another, for the purpose of locking said swivel joint (8), by a compressive force which is exerted by the grip-type part (54) on one (40) of the parts (36, 38, 40) of the joint and by a tractive force which is exerted by the threaded nut (64), via the tensioning screw (28), on another (36) of the parts (36, 38, 40) of the joint.
11. Supplementary handle according to one of the preceding claims, characterjsed in that the threads (35, 70, 66, 62) on the tensioning screw (28), the threaded nut (64) and the grip-type part (54) are oriented coaxially with the axis of swivelling (10) of the swivel joint (8).
12. A supplementary handle for a hand-held machine tool substantially as herein described with reference to the accompanying drawings.
13. A hand-held machine tool having a supplementary handle according to any one of the preceding claims.