GB2322576A

GB2322576A - Tool holder

Info

Publication number: GB2322576A
Application number: GB9803333A
Authority: GB
Inventors: Manfred Buck; Juergen Veit; Siegfried Fehrle; Wilfried Kabatnik; Volker Biermann; Joachim Hecht
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1997-02-28
Filing date: 1998-02-17
Publication date: 1998-09-02
Anticipated expiration: 2018-02-17
Also published as: JPH10277818A; CH692275A5; GB9803333D0; DE19708176A1; GB2322576B

Abstract

A tool holder comprises at least one locking element 25 which is arranged in an aperture 20 of a base element 11 of the tool holder 10. An outer, lemon-shaped end 27 of the locking element 25 is radially covered by an actuating sleeve 28. During an adjustment of the actuating sleeve 28 from a locking position into an unlocking position, the outer end 27 of the locking element 25 is first driven by an abutment ring 33 and tilted about an inner, spherical end 26, the outer end 27 adopting a radially further outward position in the locking position than in an unlocking position of the tool holder 10.

Description

2322576 1 Tool holder for a drilling and/or striking machine tool State of

the Art The invention proceeds from a tool holder for a drilling and/or striking machine tool according to the preamble of claim 1. A tool holder is already known (DE 195 21 993 Al), which comprises a base element with a receiving opening for the insertion of a tool shaft. The tool holder is provided with two locking elements, which for the axial locking of the tool engage radially With an inner end through an aperture in the base element into a recess in the tool shaft. The tool holder is provided with an actuating device, which radially covers an outer end of the locking elements with an actuating sleeve. The locking elements can be adjusted by means of the actuating device from a locking position into an unlocking position. In order to prevent the outer end from penetrating the aperture, only a small degree of movement clearance is provided between the parts which are movable relative to one another, i.e. the locking element base element and actuating sleeve. After long-term operation of the is machine tool, the locking elements can jam, more particularly under the action of dry drilling dust. In order to unlock the tool, the user then has to apply a large degree of force and in some cases a tool change even becomes impossible.

Advantages of the invention The tool holder according to the invention having the features of claim 1 offers the advantage over the state of the art that constant operational reliability of the tool holder is ensured even under extremely poor lubrication conditions. In order to lock and unlock a tool, only a small degree of force needs to be applied by the user at all 2 5 times. Hindrances during the locking and unlocking of the tool are avoided. Whilst full operational reliability is maintained, the parts which are movable relative to one 2 another are less dependent upon narrow tolerances, so that manufacture and assembly of the tool holder is facilitated.

The measures disclosed in the dependent claims allow for advantageous further 5 developments and improvements to the tool holder according to the invention.

Drawmgs An embodiment of the invention is illustrated in the drawings and is explained in flu-ther detail m the following description. Figure 1 is a longitudinal section through a tool holder according to the invention and Figures 2 to 6 are each partial views showing the tool holder m different positions during locking and unlocking of a tool shaft.

Description of the embodiment

In Figure 1 the reference numeral 10 designates a tool holder which is provided for a drilling and/or striking machine tool, more particularly for drilling with diamond tools. In this respect the tool holder 10 can either be fixedly or detachably connected 2 0 to the machine tool, which can either be manually guided or clamped in a drill stand.

The tool holder 10 comprises a base element 11 which can be rotatably driven about a longitudinal axis 12. At its end facing the tool, the base element 11 forms a receiving opening 13, into which a shaft 14 of a tool 15 can be inserted. The receiving opening 13 is conically shaped over a receiving region 16. Adjoining the receiving region 16 on the side facing the machine is a cylindrical region 17, which extends in stepped fashion into a hollow- cylindrical core region 18 of the base element 11. Arranged at the transition point between the cylindrical region 17 and J the core region 18 is an elastic ring 19, which acts as an end-face abutment and sealing element for the inserted tool 15.

Constructed m the base element 11 in the conical receiving region 16 are three apertures 20, one of which is shown in section in Figure 1 and another aperture, marked 20a, being shown m plan view. The apertures 20 are forwardly inclined relative to the longitudinal axis 12 and are each aligned on the inside with an annular groove 21 in the tool shaft 14. At least one separate drive fmger 18, which engages in positive-locking fashion in matching recesses M the tool shaft 14 and in the base element 11, is used to rotatably drive the tool 15. The apertures 20 each open on the outside into an outwardly opening pocket 22 in the base element 11.

Arranged in each of the apertures 20 is a locking element 25, which comprises beadlike ends 26, 27 connected via a web 50 having a reduced cross section. An inner, approximately spherical end 26 projects through the aperture 20 into the receiving opening 13 and therefore into the annular groove 21 in the tool shaft 14. An outer, approximately lemonshaped end 27 of the locking element 25 projects partially into the pocket 22 and projects radially partially beyond the base element 11. In this respect the locking element 25 is covered radially by an actuating sleeve 28, which concentrically encloses the base element 11 and is axially displaceably guided thereon. Towards the front, the actuating sleeve 28 is secured to the base element I I by a securing ring 29. Provided inside the actuating sleeve 28 is a shoulder 32, which is used for driving the abutment ring 33 during a displacement of the actuating sleeve 28.

On its side facing the locking element 25, the abutment ring 33 forms an abutment surface 34, which is inclined inwards towards the associated aperture 20 and on which the outer end 27 of locking element 25 rests. A support ring 3 7 with a support surface 38 is supported against the opposite side of the outer end 27. On the side 4 facmg the machine, the support ring 37 comprises a hollow-cylindrical extension 39, on which one end of a compression spring 40 is guided. The compression spring 40 is supported against an abutment disk 41, which is secured to the base element 41 via a snap ring 42. Together, the actuating sleeve 28, abutment ring 33 and support ring 37 form an actuating device 30 for adjusting the locking element 25.

Figure 1 shows the tool holder 10 with the insertion shaft 14 inserted m the receiving opening 13 and locked therein. If the tool 15 is to be removed, the actuating sleeve 28 is displaceable in the direction of an arrow 44 axially backwards into an unlocking position. The different positions of the tool holder 10 during insertion, locking and unlocking of the tool 15 are shown m Figures 2 to 6.

Figure 2 shows the tool holder 10 in its neutral position without the tool 15. The compression spring 40 acts upon the support ring 37 with spring force in an axially forward direction and brings the support ring 37 into abutment against a conical support region 56 of the outer end 27. The locking element 25 is thereby forced with a spherical abutment region 55, which adjoins the support region 56, against the abutment surface 34. As a result of the inclined abutment surface 34, the locking element 25 is subjected to a radially inward force, which forces the inner end 26 into the receiving opening 13. The abutment ring 33 rests against a collar 45 of the base element 11. Since the outer end has a larger diameter than the aperture 20, the locking element 25 cannot drop into the receiving opening 13. As a result of the two part design of the abutment ring 3 3 and support ring 3 7, the locking elements 25 can be assembled from the outside.

Figure 3 shows the tool holder 10 during the insertion of a tool shaft 14 into the receivirig opening 13. In this case, the tool shaft 14 is pushed deep into the receivm'g opening 13 until the inner end 26 of the locking element 25 is forced by the conical shaft 14 back into the aperture 20. With its outer end 27, the locking element 25 thereby forces the support ring 37 axially backwards against the force of the compression spring 40. The outer end 27 of the locking element lifts from the abutment ring 33, which remains unchanged in its position. The forcmg back of tile locking element 25 is supported by the spherical design of the inner end 26.

As soon as the tool shaft 14 is sufficiently deeply inserted into the receiving opening 13, the inner end 26 of the locking element 25 is able to snap into the annular groove 21 in the tool shaft 14 on account of the prestressing by the spring 40, so that the tool 15 is locked axially. In this"operating position of the tool holder 10 illustrated in Figure 4, the machine tool is operational.

If the tool 15 is to be removed again firom the receiving opening 13 of the tool holder 10, the actuating sleeve 28 needs to be displaced in the direction of the arrow 44 towards the machine, as shown m Figure 5. The locking element 25 is thereby firstly tilted from the abutment ring 33 into the pocket 22, until the outer end 27 comes to rests against a base surface 46 of the pocket 22. As a result of the tilting movement of the locking element 25 about its inner end 26, regions of the locking element 25 which are jammed by drilling dust, for example, are released. As a result of the effective lever arm between the outer end 27 and the inner end 26, only a small application of force is required to this end. During the tilting movement the outer end 27 of the locking element 25 can slide upon the inclined abutment surface 34 of the abutment ring 33. As soon as the outer end 27 rests against the base surface 46, the tilting movement is complete and the abutment ring 33 then also drives the locking element 25 axially. The support ring 37 is displaced axially agamst the spring force 40. As a result of this displacement the inner end 26 is drawn back into the aperture 20, so that the annular groove 21 is released.

The tool shaft 14 is unlocked as soon as the inner end 26 no longer projects into the annular groove 21. This unlocking position is illustrated in Figure 6. The web 50 6 connecting the ends 26, 27 of the locking element 25 narrows M such a manner that there is always space between the web 50 and the base element 11, even when the locking element 25 is tilted. The web 50 is provided in the opening region of the aperture 20 with a constriction, which in the direction of the inner end 26 is adjoined by a conical region 52 and then by an approximately cylindrical region 53, which extends into the spherical end 26. In addition, the aperture 20 is extended in the region of its opening into the pocket 22 by a recess 5 1 in the base element 11.

2 -1) 7

Claims

1. Tool holder for a drilling and/or striking machine tool, with a base element (11), M which a receiving opening (13) for the insertion of a tool shaft (14) is constructed, with at least one locking element (25), which for locking the tool shaft (14) engages radially with an inner end (26) through an aperture (20) M the base element (11) into the receiving opening (13) and is adjustable by means of an actuating device (30) from a locking position into an unlocking position and vice versa, characterised in that the outer end (27) of the locking element (25) adopts a radially further outward position in the locking position than in an unlocking position of the tool holder (10).

2. Tool holder according to claim 1, characterised m that the outer end (27) is filtable about the inner end (26) during the transition from the locking position into the unlocking position.

3. Tool holder according to claim 2, characterised in that the actuating device (30) comprises an adjustable actuating sleeve (28), by means of which an abutment ring (33) for the locking element (25) is axially displaceable.

4. Tool holder according to claim 3, characterised in that an abutment surface (34) for the locking element (25) is constructed on the abutment ring (33) and is inclined inwards in the direction of the associated aperture (20).

5. Tool holder according to claim 4, characterised m that the outer end (27) of the locking element (25) is forced by the force of a compression spring (40) against the abutment surface (34).

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6. Tool holder according to claim 5, characterised m that the abutment ring (33) rests against a collar (45) on the base element (11) in a neutral position of the tool holder (10) when the tool (15) is removed.

7. Tool holder according to one of claims 4 to 6, characterised in that the compression spring (40) acts upon a separate support ring (37), which rests with a support surface (38) against the outer end (27) of the locking element (25).

8. Tool holder according to one of the preceding claims, characterised in 10that the outer end (27) of the locking element (25) PrOjects partially into a pocket (22) in the base element (11), in which the outer end (27) comes to rest against a base surface (46) following an adjustment of the actuating sleeve (28) from the unlocking position.

9. Tool holder according to one of the preceding claims, characterised M that the locking element (25) is bead-shaped at its ends (26, 27), the inner end (26) being approximately spherical and the outer end (27) being approximately lemon shaped, and the ends (26, 27) being connected to one another via a web (50) with a reduced cross section.

10. Tool holder according to claim 9, characterised in that proceeding firom the outer end (27), the web (50) comprises a constriction (5 1), which is adjoined by an approximately conical region (52) with an increasing cross section followed by an approximately cylindrical region (53), which extends mto the inner end (26) (Figure 6).

11. Tool holder according to one of the preceding claims, characterised in that the outer end (27) has a larger diameter than that of the aperture (20).

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12. Tool holder according to claim 11, characterised in that the outer end (27) forms a spherical abutment region (55) for the abutment surface (34), which is adjoined by a support region (56) for the support ring (3 7) tapering conically towards the end.

13. - A tool holder for drilling and/or striking machine tools substantially as herein described with reference to the accompanying drawings.