GB2313086A

GB2313086A - Tool holder and tool for a drilling and/or hammering machine tool

Info

Publication number: GB2313086A
Application number: GB9712995A
Authority: GB
Inventors: Manfred Buck; Siegfried Fehrle; Bernd Koelle
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1995-06-20
Filing date: 1996-06-11
Publication date: 1997-11-19
Anticipated expiration: 2016-06-11
Also published as: GB2313086B; GB9712995D0

Abstract

A tool holder has a drive spindle 3, in the end of which is disposed a location hole 4a, which is provided with a cone 5 for centring and with a portion 6 for rotational driving of a tool 23. Dumbbell-shaped locking elements 9 are guided with their inner ends 10 in an opening 12 and displaceable with their outer ends 11 in a longitudinal groove 13. The outer ends 11 project into pockets 14 in an axially displaceable locking sleeve 15, which is preloaded in the direction of its locking position by means of a spring 17.

Description

Tool holder for a drilling and/or hammering machine tool The present invention relates to tool holders A tool holder is already known from EP 175 088 Al which has, inside a location hole for a push-in shaft of a tool, axial driving rails for rotary driving which, when the tool is inserted into the tool holder, engage into corresponding driving grooves in the push-in shaft.

Because ofthe driving rails, the machine-side location part has to be produced using a relatively costly manufacturing method such as, for example, forging, extrusion, circular kneading. The machine-side centring cone has to be laboriously re-worked. The tool-side centring cone may admittedly be machined by, for example, tuming or grinding. However, misalignment (offset) between the surfaces to be machined and the preformed surfaces may arise and lead to an imprecise seat of the push-in tool in the tool holder.

According to one aspect of the present invention whose scope is defined in the appended claims there is provided a tool holder for a drilling and/or hammering tool comprising a drive spindle having a location hole formed therein for receiving a push-in shaft of the tool, the holder having at least one locking element for axial and/or torsionally resistant locking of the push-in shaft in the location hole, the or each locking element being capable of protruding with its radially inner-lying end through an opening in the drive spindle into the location hole, and its radially outer end being held by a locking sleeve disposed externally on the drive spindle, wherein the or each locking element, at its ends, is fashioned in a bead-like or spherical manner, the ends being connected by a web having a reduced cross section.

According to another aspect of the present invention there is provided a tool holder in accordance with the invention in combination with a tool with a push-in shaft having an insertion cone which tapers towards a shaft end and on which at least one locking region is provided for the engagement of the at least one locking element of the tool holder, wherein disposed in front of or behind the insertion cone is a driving region, which is paraxial relative to a longitudinal axis and is of a polygonal construction for rotationally driving the push-in shaft.

A tool holder in accordance with the invention has the advantage that it permits the construction of an operationally reliable, automatic locking device comprising few structural parts.

In order that the invention may be well understood, there will now be described an embodiment thereof, given by way of example, reference being made to the accompanying drawings, in which: Figure 1 is a longitudinal section through a tool holder of the invention; Figure 2 is a cross section through a drive spindle according to line ll-llinFigure 1; Figure 3 is a view of the push-in shaft of a tool which does not form part of the present invention; Figure 4 is a section through the push-in shaft according to line IV IV in Figure 3; Figure 5 is a section through the tool holder of Figure 1 with a tool shaft inserted therein; and Figure 6 is a perspective view of a push-in shaft which does not form part of the present invention.

Referring first to Figure 1, there is shown a gearbox 1 of a drilling device, in particular a diamond core drill. Projecting from the gearbox 1 is a drive spindle 3 which is supported rotatably relative to the gearbox 1, e.g. in the bearing 2, and may be rotatably driven by means of a drive motor (not shown in detail) of the drilling device.

The drive spindle 3 has a central bore 4 for the supply of a flushing or cooling medium or alternatively for receiving a set (not shown in detail) of a striking mechanism. Towards its tool-side end, the bore 4 widens into a location hole 4a. The location hole 4a is part of a tool holder for a push-in tool 23.

The location hole 4a comprises a cone 5, which widens towards the tool-side end of the drive spindle 3 and is used to centre the push-in tool 23. The cone angle is large enough to prevent the occurrence of self-locking.

At a portion 6 of the location hole 4a positioned on the tool side in front of the cone 5, the location hole 4a is designed for rotary driving of the tool 23. The portion 6 is paraxial relative to a longitudinal axis 30 of the drive spindle 3 and carries a polygonal socket 6a. The polygonal socket 6a may, for example, take the form of a polygon or a spline shaft profile. As shown in Figure 2, the polygonal socket 6a is preferably constructed with an imaginary hexagonal basic profile 31, but with chamfered edges 32.

Provided on the machine-side after the cone 5 in the location hole 4a is a circumferential turned recess 8, in which a sealing element 7 is seated. The sealing element 7 seals off the cone 5, preventing the penetration of flushing or cooling medium. The elasticity of the sealing element 7 and the associated restoring force moreover facilitates the release of a tool 23 held on the cone 5.

For axial locking of the push-in tool 23 to prevent its falling out, at least one locking element 9, preferably two or three locking elements 9 are provided. The locking elements 9 are each disposed in an opening 12, which penetrates the drive spindle 3 radially and obliquely relative to the longitudinal axis 30. A radially inner-lying end 10 of the locking elements 9 is guided in each case in the associated openings 12 and may engage radially into the location hole 4a. A radially outer-lying end 11 of the locking elements 9 is supported in each case in an axially displaceable manner in an open longitudinal groove 13 formed in extension of the openings 12 in the drive spindle 3. The ends 11 of the locking elements 9 are held in the longitudinal grooves 13 by an axially displaceable locking sleeve 15 which embraces the drive spindle 3.

The ends 10, 11 of the locking elements 9 are of a bead-like or spherical construction. A web 9a lying between the ends 10, 11 is tapered relative thereto. The overall result is a 4 dumbbell-like shape of the locking elements 9. In another embodiment, the locking elements 9 may alternatively be formed by two straight pins disposed tangentially relative to the location hole 9 and connected to one another by a web.

With their outer ends 11, the locking elements 9 engage in a form-fit manner into pockets 14 in the locking sleeve 15. Consequently, upon axial displacement ofthe locking sleeve 15, the ends 11 are displaced in the longitudinal grooves 13 in such a way that the other ends 10 are seated more or less deeply in the openings 12. Because of the webs 9a having a tapered cross section, the locking elements 9 may be correspondingly tilted. In Figure 1, the tool holder is shown in a release position.

The locking sleeve 15 is loaded in the direction of its locking position by means of a spring 17. On the machine side, the spring 17 is supported on a supporting ring 18 which is held by means of a retaining ring 19 on the drive spindle 3. The locking sleeve 15 is displaceable counter to the action of the spring 17 by means of an actuating sleeve 16. In an axially forward direction, the locking sleeve 15 may be supported via the actuating sleeve 16 against a protective cap 21, which is secured in the direction of a tool 23 by a snap ring 22.

In Figure 3, a push-in shaft 24 of the tool 23 is shown in detail. A centring region 25 takes the form of a cone 25a corresponding to the cone 5. The centring region 25 ensures a centrical seat of the tool 23 in the location hole 4a.

Provided behind said region is a driving region 26 for rotary driving of the tool 23, which region corresponds with the portion 6 in the location hole 4a and accordingly takes the form of an external polygon 26a (see also Figure 4). The polygonal socket 6a together with the external polygon 26a forms means 20 for rotationally driving the tool 23. Also visible is a locking region 29, which has a recess 29a in the form of an annular groove. The tool 23 is provided with flow channels 34 for the flushing or cooling medium, which channels are indicated by dashed lines in Figure 3.

Locking of the tool 23 in the tool holder is effected as follows. The push-in shaft 24 is inserted into the location hole 4a until a shaft end 27 abuts the ends 10 of the locking elements 9 projecting into the location hole 4a. As a result of further insertion, the ends 10 are pressed into the openings 12, the other ends 11 of the locking elements 9 pushing back the locking sleeve 15 counter to the action of the spring 17 so that the locking elements may yield axially.

Once the push-in shaft 24 has been introduced far enough into the location hole 4a, the locking elements 9 may snap back into the recess 29a. The openings 12 are disposed at such an angle as to produce in conjunction with a chamfer 28 at the machine-side edge of the recess 29a a resultant force in the direction of the machine which brings the cone surfaces 5, 25a into mutual contact.

In Figure 5, the push-in shaft 24 is shown in the position in which it is locked in the location hole 4a. The ends 10 of the locking elements 9 engage into the recess 29a. The locking sleeve 15 is situated in the locking position. The shaft end 27 comes to lie against the sealing element 7 and elastically deforms said sealing element.

To release the tool 23 from the drive spindle 3, the actuating sleeve 16 with the locking sleeve 15 has to be displaced back against the spring 17 (see Figure 1) so that the ends 10 of the locking elements 9 are retracted into the openings 12. The tool 23 may then be removed from the location hole 4a.

Figure 6 shows an advantageous development of the push-in shaft 24. The sole difference from the push-in shaft 24 according to Figure 3 is that at least one driving groove 35 is additionally provided in the region of the cone 25a so that the push-in shaft 24 is selectively insertable into other commercially available tool holders with corresponding rotary driving rails.

The invention is not restricted to the illustrated embodiment. Thus, it is conceivable to dispose the openings 12 in the drive spindle 3 in a peripheral direction obliquely inwards and to fashion the locking sleeve 15 in a correspondingly rotatable manner. In conjunction with a spring 17 in the form of a torsion spring it is therefore possible also to create a tool holder with twist locking. Instead of a circumferential annular groove, a plurality of individual recesses may be provided in the push-in shaft 24. The rotary driving means 20 may be formed on both sides of the cone 5 or centring region 25, i.e. also on the machine side in the location hole 4a and on the end side of the push-in shaft 24.

The arrangement of said means outside of said conical centring surfaces (i.e. cone 5, centring region 25) is however very important for the sake of facilitating manufacture. The locking region 29 and the openings 12 need not necessarily be disposed in the region of the conical centring surfaces 5, 25.

Claims

1. A tool holder for a drilling and/or hammering tool comprising a drive spindle having a location hole formed therein for receiving a push-in shaft of the tool, the holder having at least one locking element for axial and/or torsionally resistant locking of the push-in shaft in the location hole, the or each locking element being capable of protruding with its radially inner-lying end through an opening in the drive spindle into the location hole, and its radially outer end being held by a locking sleeve disposed externally on the drive spindle, wherein the or each locking element, at its ends, is fashioned in a bead-like or spherical manner, the ends being connected by a web having a reduced cross section.

2. A tool holder as claimed in claim 1, wherein the opening is formed obliquely and opens externally into a radially open groove, the inner end of the locking element being guided in the opening and the outer end of the locking element on the one hand engaging into a pocket in the locking sleeve and on the other hand being guided displaceably in the groove.

3. A tool holder as claimed in claim 2, wherein the opening extends axially obliquely inwards and the groove takes the form of an axial groove, the locking sleeve being axially displaceable.

4. A tool holder as claimed in claim 2, wherein the opening is directed in a peripheral direction obliquely inwards and the groove extends in a peripheral direction, the locking sleeve being rotatable in a peripheral direction.

5. A tool holder as claimed in any one of claims 1 to 4, wherein the locking sleeve is loaded in the direction of its locking position by the action of a spring.

6. A tool holder as claimed in any one of the preceding claims in combination with a tool with a push-in shaft having an insertion cone which tapers towards a shaft end and on which at least one locking region is provided for the engagement of the at least one locking element of the tool holder, wherein disposed in front of or behind the insertion cone is a driving region, which is paraxial relative to a longitudinal axis and is of a polygonal construction for rotationally driving the push-in shaft.

7. A tool holder in combination with a tool as claimed in claim 6, wherein the driving region has a hexagonal basic profile with flattened edges.

8. A tool holder in combination with a tool as claimed in claim 6 or claim 7, wherein the driving region carries a spline shaft external gearing.

9. A tool holder in combination with a tool as claimed in any of claims 6 to 8, wherein the locking region takes the form of a circumferential annular groove.

10. A tool holder in combination with a tool as claimed in claim 7, wherein the machine side edge of the annular groove is provided with a chamfer.

11. A tool holder in combination with a tool as claimed in any of claims 6 to 10, wherein the push-in shaft additionally has in the region of the insertion cone at least one driving groove for the engagement of axial rotary driving rails of an alternative tool holder.

12. A drilling and/or hammering tool having a tool holder as claimed in any of claims 1 to 5.

Ari-dinents to the clams have been filed as follows 1. A tool holder for a drilling and/or hammering tool comprising a drive spindle having a location hole formed therein for receiving a push-in shaft of the tool, the holder having at least one locking element for axial locking of the push-in shaft in the location hole, the or each locking element being capable of protruding with its radially inner-lying end through an opening in the drive spindle into the location hole, and its radially outer end being held by a locking sleeve disposed externally on the drive spindle, wherein the or each locking element, at its ends, is fashioned in a bead-like or spherical manner, the ends being connected by a web having a reduced cross section.

2. A tool holder as claimed in claim 1, wherein the opening is formed obliquely to the longitudinal axis of the location hole and opens externally into a radially open groove, the inner end of the locking element being guided in the opening and the outer end of the locking element on the one hand engaging into a pocket in the locking sleeve and on the other hand being guided displaceably in the groove.

5 A tool holder as claimed in any one of claims 1 to 4, wherein the locking sleeve is loaded in the direction of its locking position by the action of a spring.

6. A tool holder as claimed in any of the preceding claims, wherein the location hole partially taking the form of an outwardly widening cone, and there is provided as rotary driving means in the location hole for rotationally driving the push-in shaft a portion which, when viewed from the tool insertion end of the holder, is positioned in front of or behind the cone, which extends paraxially relative to a longitudinal axis of the tool holder and which takes the form of a polygonal socket, wherein the drive spindle has a central bore for a cooling or flushing medium, and disposed at the machine-side end ofthe location hole is a turned recess, disposed in which is a sealing element serving as an end axial stop for a shaft end of the push-in shaft to be inserted into the location hole.

7. A tool holder as claimed in claim 6, wherein the paraxial portion has a hexagonal basic profile with flattened edges.

8. A tool holder as claimed in claim 6, wherein the paraxial portion carries a spline shaft internal gearing.

9. A tool holder as claimed in any one of the preceding claims in combination with a tool with a push-in shaft having an insertion cone which tapers towards a shaft end and on which at least one locking region is provided for the engagement of the at least one locking element of the tool holder, wherein disposed in front of or behind the insertion cone is a driving region, which is paraxial relative to a longitudinal axis and is of a polygonal construction for rotationally driving the push-in shaft.

10. A tool holder in combination with a tool as claimed in claim 9, wherein the driving region has a hexagonal basic profile with flattened edges.

11. A tool holder in combination with a tool as claimed in claim 9 to 10, wherein the driving region carries a spline shaft external gearing.

12. A tool holder in combination with a tool as claimed in any of claims 9 to 11, wherein the locking region takes the form of a circumferential annular groove.

13. A tool holder in combination with a tool as claimed in claim 10, wherein the machine side edge of the annular groove is provided with a chamfer.

14. A tool holder in combination with a tool as claimed in any of claims 9 to 13, wherein the push-in shaft additionally has in the region of the insertion cone at least one driving groove whereby the shaft may additionally engage with axial rotary driving rails of an alternative tool holder.

15. A drilling and/or hammering tool having a tool holder as claimed in any of claims 1 to 5.