GB2297513A

GB2297513A - Hand-held power tool with removable tool holder

Info

Publication number: GB2297513A
Application number: GB9601123A
Authority: GB
Inventors: Helmut Lebisch; Johann Rau; Helmut Wanek; Winfried Habel
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1995-02-03
Filing date: 1996-01-19
Publication date: 1996-08-07
Anticipated expiration: 2016-01-19
Also published as: IT1282091B1; GB9601123D0; ITMI960145A0; DE19503525A1; CH691167A5; GB2297513B; ITMI960145A1; DE19503525B4

Description

297513 Hand-held power tool, particularly a hammer drill and/or 5

percussion ba- er

Prior art

The invention starts from a hand-held power tool according to the precharacterizing clause of Claim 1. A hand-held power tool is already known (DE 41 00 186 Al), in which the tool holder can be mounted on a guide tube of the hand-held power tool and can be fastened thereon by means of locking balls engaging in locking recesses in the guide tube. In their locking position the locking balls are covered radially by a rotatable locking sleeve, which is prestressed in the direction of its locking position by a torsion spring. In the locking sleeve are provided radial pockets, into which the locking balls can yield after rotation of the locking sleeve. In order to facilitate the mounting of the tool holder, in addition to the locking balls there are provided guide elements which, when the tool holder is mounted on the guide tube, engage in two oppositely situated longitudinal grooves formed therein and then permit a simple turning of the locking sleeve against the force of the spring. It is a disadvantage that the tool holder can be mounted only in two rotational positions, offset by 180, relative to the guide tube. In addition, the tool holder mounted on the guide tube cannot turn relative to the guide tube.

Advantages of the invention The hand-held power tool according to the invention, which has the characterizing features of Claim

1, has in contrast thereto the advantage that the tool holder mounted on the guide tube can he fastened in a multiplicity of easily locatable rotational positions relative to the guide tube. A tool inserted into the tool holder can therefore be fastened as desired in a corresponding number of different rotational positions relative to the guide tube of the hand-held power tool, which is of advantage in particular in pure percussion operation with a forming tool, the guide tube then having 5 been locked in respect of rotation.

Through the measures specified in the dependent claims, advantageous developments and improvements of the hand-held power tool indicated in Claim 1 are possible.

Drawing One exemplary embodiment of the invention is illustrated in the drawing and explained in greater detail in the following description. Figure 1 shows a section through the front part of a hammer drill, Figure 2 shown a developed view of the part of a guide tube at is the tool end, and Figure 3 shown an elevation of a locking sleeve of the hammer drill.

Description of the exemplary embodiment

The f ront part, shown in Figure 1, of a hanner drill 10 has a guide tube 11 projecting out of a caning 12. The guide tube 11 can be rotationally driven via a gear unit (not shown in detail) by a drive motor, which in likewise not shown. in the interior of the guide tube 11 a percussion element 13 in guided for axial reciprocating movement. A tool holder 14 mounted on the guide tube 11 has a main body 15 having a hollow cylindrical shape to receive a tool shank 16. At its end facing the guide tube 11 the main body 15 forms a hollow cylindrical connection part 17 which has an inside diameter larger than the main body 15 and which can be pushed externally onto the guide tube 11. The tool shank 16 can be locked inside the main body 15, for example by the means known from DE 41 00 186 Al, which are not the subject of the present application. In the case of the example, the tool shank 16 in part of a forming tool 18.

For the fastening of the tool holder 14 on the guide tube 11 use in made of two locking elements 20, of which one locking element 20 is shown in the top half of the section in Figure 1. The locking elements 20 are in each case arranged in an inwardly tapering aperture 21 in the connection part 17 of the main body 15. In this case, the aperture 21 has dimensions such that the locking elements 20, which are for example in the form of locking balls, partly project radially inwards beyond the aper ture 21. Associated with the locking elements 20 are a plurality (six in the case of the example) of locking recesses 22 distributed in the circumferential direction in the outer periphery of the guide tube 11. The locking recesses 22 are approximately conical in shape. Their opening cross-section is dimensioned such that the locking elements 20 can engage radially in them.

The locking elements 20 are covered radially by a locking sleeve 23 and held in the locking position shown in Figure 1. Through the engagement of the locking elements 20 in the locking recesses 22 the tool holder 14 is fastened axially and in the circumferential direction on the guide tube 11.

The locking sleeve 23 shown in detail in Figure 3 has pockets 24 distributed in the circumferential direction on its inner side and serving to unlock the locking elements 20. Longitudinal notches 25 are provided on the outer periphery of the locking ring 23 and serve for the rotationally secure connection to a grip sleeve 26 of the tool holder 14. The grip sleeve 26 is loaded circumferentially, in the direction of its locking position, by a torsion spring 27. The torsion spring 27 is engaged by its one end 28 in a slot 29 in the grip sleeve 26. At the other end the torsion spring 27 is connected securely to the main body 15 for rotation therewith, and is supported on the latter. The grip sleeve 26 can be turned, relative to the main body 15, against the spring moment of the torsion spring 27, the locking ring 23 being correspondingly moved thereby. In this way the pockets 24 can be brought into radial coincidence with the aperture 21, so that the locking elements 20 can yield radially to unlock the tool holder 14.

A guide element 3 0 in the f orm of a guide ball is held in a corresponding aperture 31 in the connection part 17 of the main body 15. Compared with the apertures 21 for the locking elements 22, the aperture 31 is arranged axially nearer the machine end of the main body 15. In all, 2 guide elements are provided, and these are arranged diametrically opposite one another. For reasons of graphic representation the bottom half of Figure 1 in correspondingly shown turned by 90 degrees into the plane of the drawing, so that only one of the tw o guide elements 30 can be seen. In the guide tube 11 there is a circumferential annular groove 33 in which the guide elements 30 engage. Two axial longitudinal grooves 32 extend f rom. the tool end of the guide tube 11 to the annular groove 33 (ace also Figure 2). The longitudinal grooves 32 serve the purpose of axially guiding the guide elements 30 during the mounting of the tool holder 14 on the guide tube 11.

in order to mount the tool holder 14 it in first turned until the guide elements 30 and the guide groove 32 coincide. The tool holder 14 is then mounted on the guide tube 11, with the guide elements 30 engaging in the corresponding guide groove 32. The grip sleeve 26 can then be turned against the f orce of the torsion spring 27, because the main body 15 can be supported on the guide tube 11 by means of the guide elements 30. The locking elements 20 can now penetrate into the pockets 24, so that the main body 15 together with the locking body 20 can be pushed axially further onto the guide tube 11. After the grip sleeve 23 has been released, the locking sleeve 23 snaps back into its locking position when the locking element 20 is situated radially over the locking recess 22. The locking sleeve 23 then pushes the locking elements 20 into the corresponding locking recesses 22. The guide elements 30 then project into the annular groove 33.

If it is now desired to change the rotational position of the tool holder 14 relative to the guide tube 11, the locking sleeve 23 must again be turned against the f orce of the torsion spring 27. During this action the main body 15 is supported on the guide tube 11 by means of the locking elements 20. As soon as the locking elements 20 penetrate sufficiently deeply into the corresponding pockets 24, the main body 15 of the tool holder 14 can be turned relative to the guide tube 11, during which action it is guided by the guide elements 30 engaging in the annular groove 33. In this way simple location of the desired rotational position is possible, because the guide elements 30 prevent the tool holder 14 from being pulled off in a rotational position in which the guide elements 30 do not coincide with the guide grooves 32. in the exemplary embodiment illustrated six locking recesses 22 and two guide grooves 32 are provided is and are distributed regularly over the periphery. A total of eight catch positions spaced 45 degrees apart are therefore provided for the tool holder 14.

The invention is not restricted to the exemplary embodiment illustrated. It can for example also be advantageously applied when the locking elements are fixed to the guide tube and the locking recesses are situated in the main body. The guide grooves or the annular groove may also be formed in the main body and the guide elements be held in the guide tube. More or fewer than two locking elements or guide elements may also be provided. The number and orientation of the selectable rotational positions are determined by the number of locking recesses distributed over the periphery. in order to permit the finest possible catching, it is advantageous to provide the largest possible number of locking recesses, for example ten. Together with two guide grooves, twelve possible catch positions are then obtained for the tool holder. Given regular distribution over the periphery, the tool holder can thus be fastened at intervals of 30 degrees.

CLATM is I. Hand-held power tool, particularly a hammer drill and/or percussion hammer, having a tool holder (14) which has a main body (15) which can be connected by means of at least one locking element (20) to a guide tube (11) of the hand-held power tool, the at least one of the locking elements (20) being held in an aperture (21) in the main body (15) and being designed for selective engagement, by unlocking means, in one of at least two locking recesses (22) distributed in the circumferential direction in the guide tube (11), characterized in that at least one guide element (30) is provided which is arranged, in a position axially offset relative to the at least one of the locking elements (20), in another aperture (31) in the main body (15), and, with the tool holder (14) fixed on the guide tube (11), engages in a circumferential annular groove (33) situated in the guide tube (11) and correspondingly axially offset relative to the locking recesses (22).

Claims

2. Hand-held power tool according to Claim 1, characterized in that for

the at least one of the guide elements (30) at least one guide groove (32) is provided, which extends axially from the tool end of the guide tube (11) and leads into the annular groove (33).

3. Hand-held power tool according to Claim 1, characterized in that the annular groove (33), viewed from the tool end of the guide tube (11), is arranged axially behind the locking recesses (22).

4. Hand-held power tool according to one of the preceding claims, characterized in that the locking element (20) is in the form of a locking ball and the guide element (30) is in the form of a guide ball.

S. Hand-held power tool according to Claim 4, characterized in that a total of two locking elements (20) arranged dialm trically opposite one another and, turned by 90 degrees, two guide elements (30), likewise arranged diametrically opposite one another, are provided.

6. Hand-held power tool according to one of the preceding claims, characterized in that the number of locking recesses (22) exceeds the number of locking elements (20).

7. A power tool substantially as herein described with reference to the accompanying drawing