GB2328169A

GB2328169A - Tool holder for a rotary hand-held machine

Info

Publication number: GB2328169A
Application number: GB9815883A
Authority: GB
Inventors: Ernst Kraenzler; Klaus Klingenstein; Karl Garatwa
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1997-08-12
Filing date: 1998-07-21
Publication date: 1999-02-17
Anticipated expiration: 2018-07-21
Also published as: CN1138617C; ITMI981681A0; GB2328169B; GB9815883D0; CN1207979A; ITMI981681A1; DE19734763A1

Abstract

A tool holder for a rotary hand-held machine 10 has guiding means 18 to accommodate the splined shank 23 of a tool 17. Toothed recesses in the guide means cooperate with the splines to ensure that the shank and guide means are rotatably coupled. The guide means is unitary with the end of the machine spindle 12 which rotates about an axis 11. Separate retaining means 28, comprising a disc-shaped retaining element 26 biassed by a spring 42, enable the shank to be axially held with the holder.

Description

2328169 1 Tool holder for a hand tool machine and tool-shank insertable

therein

Background art

The invention proceeds from a tool holder for a hand tool machine according to the preamble of claim 1 and from a tool shank insertable therein according to the preamble of claim 6. A tool holder for a hand tool machine and a tool shank insertable therein are already known from DE 196 33 677 AI. In said tool holder, separate regions are provided for guidance, rotational coupIffig and axial fixing of the tool and cooperate with corresponding regions of the tool shank. Separation of the functional regions offers the advantage that each region in itself has excellent flinctional properties. There is however the inherent drawback that each of the individual functional regions has to be of a minimum length, resulting as a whole in a relatively large overall length of the tool holder and of the tool shank.

Advantages of the invention The tool holder for a hand tool machine according to the invention having the features of claim 1 and the tool shank according to the invention having the features of claim 6 have the advantage that the overall length is reduced while retaining equally good flinctional properties and the torque capacity is improved while retaining the same guiding properties. This is achieved in that the rotational coupling means forming a form closure in a peripheral direction are axially superimposed on the guide means.

Advantageous development and improvements of the tool holder indicated in claim 1 and of the tool shank indicated in claim 6 are possible by virtue of the measures outlined in the dependent claims.

2 It has proved particularly advantageous to form the rotational coupImig means and the guiding means in a location opening because it is then possible to dispense with additional structural parts such as, for example, sleeves.

It is also advantageous to design the rotational coupling means as a tooth system because such a system, while having a high torque capacity, is relatively easy to manufacture. The tooth system has the added advantage of alerting the user not to use the tool provided with the shank according to the invention in conventional machines such as straight sanders because said machines may frequently be operated at a very high speed which is not permitted for specific tools such as brushes. Because of the tooth system, the shank end has a very large diameter which precludes insertion into conventional location openings.

By designing the guiding means as guide surfaces which lie in a tip circle and/or a root circle of the tooth system, a simple axial superimposition of the rotational coupling means and guiding means combined with good flinctional properties and ease of manufacture is possible.

By designing the retaining means as clamping means, only a cylindrical clamping surface is required on the shank.

It is also advantageous to dispose the guiding surfaces in the root base of the toolside tooth system because they are then protected by the longitudinal teeth, which project radially from the shank, from damage resulting in impaired guidance.

When the diameter of a retaining portion is markedly increased compared to the diameter of the tooth system, chucking is prevented if the tool shank is not yet 3 seated far enough in the tool holder. Incorrect operation may also be prevented when the retaining portion is adjomied by a conical transition, which is detected by a spring plate for the purpose of release.

By virtue of disposing an at least partially hollow-cylindrical receiving part at the tool end of the tool shaft, a simple way of forming a connection between tool and tool shank is provided.

Drawings An embodiment of the invention is illustrated in the drawings and described in detail below. Figure 1 shows a longitudinal section through a tool holder according to the invention with a tool shank according to the invention inserted therein, Figure 2 an enlarged view of a tool shank according to Figure 1, Figure 3 a cross section of the tool shank along the line III-III Mi Figure 2, Figure 4 a section through the guiding region of the tool holder of Figure 1, and Figure 5 a longitudinal section through a further tool holder with a tool shank according to the invention inserted therem.

Description of the embodiment

Figure 1 shows the tool-side part of a hand tool machine 10. The hand tool machine 10 comprises a spindle 12, which is drivable so as to rotate about a longitudinal axis 11 and is rotatably mounted in a housing 13 of the hand tool machine. The spindle 12 is set in rotation by means of a drive, which is not described in detail. Situated concentrically in the spindle 12 at its tool-side end 12a is an axial location opening 14 for receiving and guiding a tool shank 16. The tool shank 16 is non-rotatably connected to a tool 17. The tool 17 in the 4 embodiment takes the form of a brush. It may however alternatively be another tool with a rotating and axially fixed working motion, such as, for example, a drill, screwdriver or sander.

The location opening 14 forms guiding means 18 for axial guidance of the tool shank 16 and is moreover provided with means 21 of effecting positive rotational coupling of the tool shank 16, which are axially superimposed on the guiding means 18. The guiding means 18 are formed by machine-side guide surfaces 18a and/or 18c, which cooperate with tool- side guide surfaces 18b and/or 18d. The rotational coupling means 21 are formed by an axially extending spindle-side tooth system 22 having longitudinal teeth 22a, which engage positively into corresponding recesses 23a of a tool-side tooth system 23.

Mounted axially in front of the guiding means 18 and the rotational coupling means 21 are retaining means 28 for axially locking the to ol shank 16 mi the location operuing 14. The retaining means 28 take the form of clamping means. In their design and mode of operation, the retaining means 28 correspond to the clamping means disclosed in DE 196 33 677 AI. A disc-shaped retaining element 26 supported in an articulated manner on the machine and having a through-opening 24 embraces the tool shank 16. The retaining element 26 tilts under spring action, with the result that it is clamped firmly against a cylindrical retaining portion 25 of the tool shank 16 projecting through the through- opening 24. By straightening the retaining element 26 the effective cross section of the through-opening is increased once more, resulting in cancellation of the clamping action and release of the tool 17. For a more detailed description, reference is made to DE 196 33 677 AI, to which express reference is made here for the purpose of disclosure.

Figure 2 shows the tool shank 16 in greater detail. The tool shank 16 at its machine-side end 16a forms the tooth system 23 comprising a total of six teeth 23b and six recesses 23a each lying between adjacent teeth 23b. The tooth system 23) is inscribed in a cylindrical shank portion 19. An outside diameter d of the shank portion 19 corresponds substantially to a tip diameter K of the teeth 23b.

The shank tooth system 23 extends from the shank end 16a axially over almost the entire length of the shank portion 19. The shank portion 19 at the tool-side end verges via a conical transition 27 into the cylindrical retaining portion 25, which has a larger diameter D than the shank portion 19.

The retaining portion 25 is adjoined at the tool-side end by a conical chamfer 29, which verges into a cylindrical free portion 30 having a larger diameter. The free portion 30 is delimited at the tool-side end by a collar 3 1. At the other side of the collar 3 1, the tool shank 16 terminates in a receiving portion 32 for fastening of the tool 17. In the embodiment, the receiving portion 32 towards the tool-side end 16b is hollow. The tool 17, after being mounted onto the receiving portion 32, is preferably positively connectable to the tool shaft 16 through flanging of an edge 32a. The tool 17 may however also be connected, e.g. by screws, rivets etc., to the tool shank 16 or may also be integrally formed thereon.

In the views of the tooth systems 22, 23 shown in Figures 3 and 4, lateral flanks of the teeth 22a, 23b serving as rotational coupling means 21 are evident. On the shank, the guiding surfaces 18b, disposed substantially in a tip diameter K of the tooth system 23 serve as guiding means 18. The guiding surfaces 18b cooperate with the guiding surfaces 18a on the machine, which are disposed substantially with a root diameter F. The tip diameter K of the tooth system 23 corresponds in the present case to the root diameter F of tooth system 22 so that the guiding 6 surfaces 18a, b are seated snugly one on the other with little displacement clearance and guarantee good guidance of the tool shank 16.

In addition or as an alternative to the guiding surfaces 18a, b, internal guiding surfaces 18c, d may be provided, which lie substantially in the root circle F2 of the shank tooth system 23 and in the tip circle K2 of the machine tooth system 22.

Insertion of the shank 16 into the tool holder 20 is effected in the followmg manner. First the retaining element 26 is straightened by displacing a handle 38, a shoulder 39 on a spring plate 40 engaging behind the retaining element 26 and holding the latter in its opening position. Then the tool shank 16 is pushed mito the tool holder 20, the tool shank 16 initially having to be rotated until the tooth systems 22, 23 fit one into the other. When the tool shank 16 has been pushed far enough into the location opening, a free end 41 of the spring plate 40 slides radially outwards along the chamfer 29 between retaining portion 25 and free portion 30, with the result that the shoulder 39 releases the retaining element 26 and a spring 42 tilts the retaining element 26 for clamping purposes.

Figure 5 shows a further tool holder 20', which differs from the tool holder 20 in that the tooth system 22 is disposed on a sleeve 35 slipped non-rotatably onto the spiridle 12. The location opening 14 takes the form of a bore 36, the diameter of which corresponds to the tip diameter K of the tool shank 16. The separate arrangement of the functional regions in the tool holder 20' corresponds to the arrangement in the tool holder known from DE 196 33 677 AI. The tool shank 16 according to the invention may therefore be inserted also into said tool holder 20', provided that the latter's location opening 14 is timed to the diameter d of the shank's guiding surfaces 18b.

7

Claims

1.

3.

4..

Tool holder for a hand tool machine for operating with a rotating and axially fixed tool, e.g. for drilling, screwing, brushing, sanding or the like, which tool holder has a location opening (14), into which a tool shank (16) of a tool (17) is partially axially insertable, and is provided with guiding means (18) for axial guidance of the tool (17) as well as with means (2 1) forming a form closure with the tool (17) for rotational couplMig of the tool (17) and has separate retaining means (28) for axial locking of the tool (17), which are mounted axially in front of the rotational coupling means (2 1) and the guiding means (18), characterized in that the rotational coupling means (2 1) are axially superimposed on the guiding means ( 18).

Tool holder according to claim 1, characterized in that the rotational coupling means (21) and the guiding means (18) are formed in a location opening (14), which is disposed concentrically in a spindle (12) of the hand tool machine.

Tool holder according to claim 2, characterized in that the rotational coupling means (2 1) comprise a tooth system (22); which extends along the location opening (14) and cooperates with a tooth system (23) on the tool shank (16).

Tool holder according to claim 2 or 3, characterized Mi that the guiding means (18) comprise guiding surfaces (18a) lying substantially in a root circle (34) of the machine-side tooth system (22) and/or guiding surfaces ( 1 8c) lying substantially in a tip circle 8 (43) of the machine-side tooth system (22).

5.

6.

7.

8.

9.

Tool holder according to claim 1, characterized in that the retaining means (28) take the form of clampmg means.

Tool shank for chucking tools in hand tool machines, which is provided with guiding means (18) for axial guidance of the tool (17) as well as with means (23) forming a form closure with the hand tool machine for rotational coupI Mig of the tool ( 17) and which has a cylindrical retaining portion (25) for axial locking of the tool (17), which retaining portion is mounted axially in front of the rotational coupling means (21) and the guiding means (18), characterized in that the rotational coupling means (2 1) are axially superimposed on the guiding means (18).

Tool shank according to claim 6, characterized in that it comprises a cylidrical shank portion (19), which is disposed at a machineside end (16a) of the tool shank (16) and along which a tooth system (23) forming the rotational coupling means (2 1) extends axially.

Tool shank according to claim 7, characterized in that the shank tooth system (23) comprises a total of six longitudinal teeth (23b), which are arranged so as to be uniformly distributed over the periphery of the tool shank (16).

Tool shank according to claim 7 or 8, characterized in that the shank portion (19) has, as guiding means (18), external guiding surfaces (18b) lying substantially in an outer tip circle K of the shank tooth 9 system (23) and/or internal guiding surfaces (18d) lying substantially in an inner root circle F2 of the tool-side tooth system (23).

10.

11.

12.

13.

14.

Tool shank according to one of claims 7 to 9, characterized in that the cylindrical retaining portion (25) axially adjoins the shank portion (19), the retaining portion having a larger outside diameter than the shank portion (19).

Tool shank according to claim 10, characterized in that the retaining portion (25) is adjoined by a conically thickening chamfer (29).

Tool shank according to claim 10 or 11, characterized in that the tool shank (16) at its tool-side end (16b) forms a cylindrical receiving portion (32) for the tool (17), which receiving portion is separated by a collar (3 1) from the machine-side part of the tool shank (16) and towards the end is of a hollow cylindrical construction.

A tool holder substantially as herein described with reference to the accompanying drawings.

A tool shank substantially as herein described with reference to the accompanying drawings.