GB2294220A

GB2294220A - Toolholder dust cap

Info

Publication number: GB2294220A
Application number: GB9519785A
Authority: GB
Inventors: Wilbert Reibetanz; Otto Baumann; Rolf Mueller
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1994-10-17
Filing date: 1995-09-28
Publication date: 1996-04-24
Anticipated expiration: 2015-09-28
Also published as: DE4436860A1; IT1276908B1; ITMI952062A0; ITMI952062A1; GB9519785D0; GB2294220B; DE4436860B4; CH690904A5

Description

Prior Art

1 - Toolholder for a hand-held Dower tool 2294220 The starting point of the invention in a toolholder for a hand-held power tool, particularly for use in drills or percussion drills and in hammer drills or percussion hammers, according to the pre-characterizing clause of Claim 1. A toolholder of this kind in already known (BP 548 702 A1), which in In the form of a drill chuck having clamp jaws and in provided with a dust cap for protection against the penetration of drilling dust. By means of an inwardly facing circumferential bead the dust cap in held by friction in a recess in a drill chuck -body of the toolholder. During drilling it turns together with the drill chuck body. If contact in then is made between the dust cap and the wall surface, the cap may damage the wall or at least produce an impression in it. The dust cap may then suffer abrasion and damge on its exterior and on its interior in the region of the bead.

In addition, a toolholder is known on the market which is provided with a dust cap fastened by means of an annular retaining disc on a hollow cylindrical drill chuck body of the toolholder. The retaining disc bears axially on one side against a collar on the drill chuck body, and on the other side is secured by means of a locking ring against axial displacement. If contact in made with the wall, the dust cap rotating together with the drill chuck body is braked. It can then twist in the circumferential direction relative to the drill chuck body. However, because of the nature of the mounting It is then not possible to exclude rubbing contact with the locking ring and, particularly under radial load, also with the drill chuck body, so that undesirable wear may also occur with this known dust cap if contact is made with the wall.

Advantages of the Invention The toolholder according to the invention, which has the characterizing features of Claim 1, has in comparison therewith the advantage that undesirable wear on the dust cap, caused for example by contact with the wall during drilling, in avoided.

Through the measures indicated in the subclaims advantageous developments of the toolholder mentioned in Claim 1 are possible. A compact construction of the toolholder is ensured by the mounting of the dust cap by means of a retaining disc, a reinforcement disc and a locking ring interposed between them. BY =cans of an inwardly projecting bead the dust cap is reliably held with axial immovability against the retaining ring. The run- up surface on the bead facilitates the fitting of the dust cap.

Drawing An exemplary embodiment of the invention is shown in the drawing and explained in greater detail in the following description. Figure 1 shows an elevation of a hammer drill having a toolholder, and Figure 2 shows a partial section through a toolholder constructed in accordance with the invention.

Description of the Exemplary Embodiment

A hammer drill designated 10 in Figure 1, an an example of a hand-held power tool, has a caning 11. The hammer drill 10 has a toolholder 12 which is connected to a tool end of a rotating drive shaft (not further shown) and can be rotationally driven thereby. A tool 13 can be inserted into the toolholder 12. To give protection against dust, drillings, moisture and the like, the tool holder 12 is provided with a dust cap 14, which embraces the front part of the toolholder 12.

In Figure 2 the toolholder 12 is shown in greater detail.. The toolholder 12 has a main body 15 which forms a central, axially extending mounting opening 16 for the tool 13. The mounting opening 16 is covered at the tool end by the dust cap 14. In the case of the example the toolholder 12 is in the form of a known combination drill chuck which, in addition to a holder for fluted-stem tools for percussion or hammer drill operation (not shown in Figure 2), has a jaw chuck for round-stem tools for pure drilling. For this purpose the jaw chuck is equipped with three clamp jaws 17, of which one is shown in Figure 2. The clamp jaws 17 arranged in obliquely extending bores in the main body 15 are adjustable axially, and thus also radially, by means of an adjusting ring 18 drivingly connected to the clamp jaws 17. The adjusting ring 18 is actuated by means of an actuating sleeve 19, which concentrically embraces the toolholder 12 and adjusting ring 18. The actuating sleeve 19 is mounted for rotation relative to the main body 15 and connected to the adjusting ring 18 for rotation therewith.

The dust cap 14 is mounted at the tool end 20 of the main body 15. The dust cap 14 is mounted there by means of a bearing 21 which ensures the rotatability of the dust cap 14 relative to the toolholder 12 or, in the case of the example, to the main body 15 of the tool- holder 12.. The dust cap 14, which is equipped with two lips 22 spaced axially apart and with radial openings 23 interposed therebetween, is provided with an annular reinforcement disc 24, which takes rearwardly directed 30 axial loads acting on the dust cap 14. The reinforcement disc 24 is supported against a locking ring 26 seated in a circumferential groove 25 in the main body IS. The reinforcement disc 24 is pressed into an annular groove 30 in the dust cap 14. it may also already be connected to the dust cap 14 during the production of the latter, by moulding therearound. A likewise annular retaining disc 27 is also pushed onto the toolholder 12, and is arranged axially behind the locking ring 26. The reinforcement disc 24 - 4 and the retaining disc 27 are approximately equal in size. The dust cap 14 engages behind the retaining disc 27 by means of an inwardly projecting circumferential bead 29, whereby it in secured on the main body 15 against axial displacement in the forward direction. The reinforcement disc 24 and the retaining disc 27 are held in the dust cap 14 by friction and are seated on the main body 15 with clearance permitting movement, so that they and also the dust cap 14 can twist with slight friction relative to the main body 15. The reinforcement disc 24, the locking ring 26 and the retaining disc 27 have slight axial clearance relative to one another and at the same time form a labyrinth seal between the dust cap 14 and the main body 15 - At its outer edge 28 the dust cap form a scaling bead which on rotation thrown off, in the radial outward direction, drillings encountered there and covers a gap remaining between the dust cap 14 and the actuating sleeve 19.

For the purpose of f itting the dust cap 14 the retaining disc 27 is first pushed onto the main body 15.

The locking ring 26 in then inserted into the groove 25, whereby the retaining disc 27 in secured axially on the main body 15. The dust cap 14, which is made of elastic material and is provided with the reinforcement disc 24, is then fitted onto the main body 15 and pulled axially over the retaining disc 27 by means of its inwardly projecting bead 29. For this purpose the dust cap 14 is provided with a conical run-up surface 31, which centres the dust cap 14 on the retaining disc 27 when it is pushed onto the main body 15. The inwardly projecting bead 29 then engages radially behind the retaining disc 27, so that the dust cap 14 is held axially immovable on the main body 15. The actuating sleeve 19 need not be moved during the fitting of the dust cap 14.

The centring, guidance and locking of the dust cap 14 by means of the discs 24, 27 make a short cons truction possible. The dust cap 14 is thereby also secured against tilting, so that direct contact between the dust cap 14 and the toolholder 12 is always avoided.

The invention is not restricted to the exemplary embodiment illustrated. The essential point ia that the dust cap 14 in mounted for rotation relative to the toolholder 12. It may consequently also be for example mounted rotatably on the actuating sleeve 19, which for this purpose would have to be designed accordingly. instead of the plain bearing previously described it is of course also possible to provide a rolling- contact bearing. The Invention is in principle applicable to all hand-held power tools in which a mounting opening of a toolholder has to be protected against the penetration of dust particles and the like, in relation to a tool which in to be inserted into it, by means of a dust cap.

- Consequently, it can in-particular also advantageously be -applied to pure drills.

claims Toolholder for a hand-held power tool, particu larly for a drill or percussion drill or for a hammer drill or percussion hammer, which has a main body (15) provided with a mounting opening (16) into which a tool (13) can be inserted and which can be covered by means of a dust cap (14) for protection against the penetration of dust, drillings, moisture and the like, characterized in that the dust cap (14) is mounted on the toolholder (12) for rotation relative thereto by means of a bearing (21) which has at least two discs (24, 27) which are arranged for rotation on the toolholder (12) with radial clearance permitting movement and are separated from one another by a locking ring (26) axially fixed relative to the tool is holder (12).

Claims

2. Toolholder according to Claim 1, characterized in that the bearing (21)

has a retaining disc (27) and a reinforcement disc (24), which are received non-twistably in the dust cap (14) when the latter in fitted.

3. Toolholder according to Claim 2, characterized in that the bearing (21) is arranged on the main body (15) of the toolholder (12).

4. Toolholder according to Claim 2 or 3, character ized in that by means of an inwardly projecting circum ferential bead (29) the dust cap (14) axially engages positively behind the retaining disc (27).

5. Toolholder according to Claim 4, characterized in that the dust cap (14) has a run-up surface (31) on its bead (29).

6. Toolholder according to one of Claims 2 to 5, characterized in that the reinforcement disc (24), the locking ring (26) and the retaining disc (27) have slight axial clearance relative to one another.

7. Toolholder according to one of Claims 2 to 6, characterized in that the reinforcement disc (24) and the retaining disc (27) are approximately equal in size.

8. Toolholder according to one of the preceding claims, characterized in that an outer edge (28) of the dust cap (14) is reinforced radially outwards in the form of a bead. - 9. A toolholder substantially as herein described with reference to the accompanying drawing.