GB2286351A

GB2286351A - Tool holder

Info

Publication number: GB2286351A
Application number: GB9500169A
Authority: GB
Inventors: Joerg Faelchle
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1994-01-21
Filing date: 1995-01-05
Publication date: 1995-08-16
Anticipated expiration: 2015-01-05
Also published as: JPH07214406A; JP3579478B2; CH688404A5; GB2286351B; DE4401663A1; GB9500169D0

Description

1 2286351 Tool Holder State of the Art

The invention relates to a tool holder of the type described in Claim 1. Several variants of such-tool holders are known from the state of the art.

For instance, DE-PS 32 05 063 describes a tool holder which is quite satisfactory in its mode of operation. The locking element of this tool holder is a ball which is prevented from moving radially in its resting position by a part of the sliding sleeve. When the shaft of the tool is introduced, the ball is pressed by the end of said shaft against a springloaded ring. The displacement of the ball and the ring against the force of the spring causes the ball to be displaced also in relation to the part of the sliding sleeve blocking it and to be capable of moving away radially and then latching in the groove-shaped recess of the shaft of the tool. In order to release the tool the sliding sleeve must be displaced in the direction of the drive member against the force of the same spring so that the ball can again move away radially, but this time on the tool side, from the blocking part of the sliding sleeve. In order to avoid the unintentional release of the tool the spring must be of suitably hard construction. But this has the consequence that when the tool is being inserted a considerable force needs to be exerted in order to displace the ball and the ring against the spring tension, and this 2 force has to be applied by the user by way of the tool. That is to say, the tool holder according to this printed publication is not very easy to manage. A further disadvantage consists in that the known tool holder contains many component parts, resulting in costly manufacture and assembly.

Advantages of the Invention With the present invention a tool holder is created which is easy to manage and which consists of fewer component parts so as to simplify its manufacture and assembly.

This is achieved by virtue of a tool holder of the type stated in the introduction having the characteristics cited in the characterising portion of Claim 1.

When the tool is inserted, the locking element only needs to be displaced against the slight force of the soft end of the spring, whereas an unintentional displacement of the sliding sleeve is prevented by the overall force of the hard spring. Due to the modified construction and the direct coupling of the end of the spring to the locking element, the provision of a ring is no longer necessary.

Without displacement of the sliding sleeve the obliqueness of the aperture permits a movement of the locking element leading radially outwards when the tool is introduced but has a blocking effect against a movement of the tool in the opposite direction.

Additional advantageous developments of the tool holder according to the invention can be inferred from the following description of an exemplary embodiment and from the dependent claims.

A k.

3 Drawing The enclosed drawing shows a preferred embodiment of the invention, whereby in particular Fig. 1 shows the tool holder according to the invention when the tool is being inserted, Fig. 2 shows the tool holder with a tool inserted and Fig. 3 shows the tool holder when the tool is being removed.

Description of the Exemplary Embodiment

In each of the Figures only the drive member 6 is represented that pertains to a drill hammer which is not shown, whereby said drive member protrudes from the casing.

Said drive member 6 has the form of a tool spindle which undergoes an impacting and/or rotating movement. on its free end projecting from the casing of the drill hammer the drive member 6 has a device for torque transmission in the form of an external spline-shaft profile. The external spline-shaft profile is intersected at a right angle by an annular groove 8 extending around the periphery of the front end of the drive member 6, the depth of said annular groove corresponding to the depth of the grooves of the external spline-shaft profile. The front of the drive member 6 has a plane stop face 9.

The tool holder consists essentially of a basic sleeve 1, on the outside of which an axially mobile sliding sleeve 2 is guided. The sliding sleeve 2 may be manufactured from metal or plastics. The basic sleeve 1 has two coaxially adjacent receiving bores of different diameters: a rear bore facing towards the drill hammer with a relatively large diameter for receiving the drive member 6, and a second bore opening out on the other front end with a relatively small diameter for receiving the shaft 13 of the tool.

4 on the end region of the basic sleeve 1 on the machine side there is arranged an oblique bore 11 in which a locking ball 12 is displaceably arranged as a connecting element for the purpose of connecting the drive element 6 to the basic sleeve 1. The lccking ball 12 engages in the annular groove 8 of the drive member 6 and in this manner locks the basic sleeve 1 on the drive member 6. In the peripheral region in which the oblique bore 11 is provided the basic sleeve 1 exhibits a peripheral groove 18 in which one end 5c of a conical compression spring 5 is fixed, said end exhibiting the smaller diameter. The locking ball 12 is prevented from falling out of the oblique bore 11 by the end 5c of the compression spring 5 fixed in the peripheral groove 18. By reason of the width of the annular groove 8 the basic sleeve 1 has a definite degree of axial freedom in relation to the drive member 6.

The shaft 13 of the tool intended to be accommodated in the tool holder has at its rear end a plane stop face 7 provided with a chamfer, said stop face being axially adjacent to the stop face 9 of the drive member 6. Via these two stop faces 7, 9 in contact with one another axial impacts are transmitted from the drive member 6 to the shaft 13 of the tool. With the tool holder according to the invention it is possible for known tools to be used such as also find application, eg, in patent document DE-PS 32 05 063 which was mentioned in the introduction to the specification. on the external surface of the shaft 13 of such a known tool there are disposed at opposite points on a diagonal two groove-shaped recesses 15 which are closed on both sides in the axial direction. on a diagonal located perpendicular thereto there are additionally arranged on the shaft 13 of the tool two opposite rotary driving grooves 19 opening out at the end of the shaft, in which grooves there engage corresponding rotary driving elements in the receiving bore of the basic sleeve 1. As is apparent from Fig. 2, when a tool has been inserted a 0 locking element 3 engages in the recess 15, said locking element being displaceably arranged in an aperture 17 of the basic sleeve 1. The aperture 17 is an oblique bore, the external orifice of which is arranged nearer to the end of the basic sleeve 1 on the machine side and the inner orifice of which is arranged nearer to the end of the basic sleeve 1 on the tool side. The locking element 3 is a peg, the inner rounded end of which engages in the recess 15 of the shaft 13 of the tool and the outer end of which is coupled to the free, soft end 5a of the conical compression spring 5. For this purpose there is formed on the outer end of the locking element 3 an eye 10, through which the end 5a of the spring grips. The end 5a of the spring is capable of being set back axially in relation to a partial winding 5b of the compression spring 5 adjoining the sliding sleeve 2 under initial stress of the compression spring 5. The force required to do this is considerably less than the initial stress of the compression spring 5, since the initial stress is transmitted via the partial winding 5b to the sliding sleeve 2. and essentially therefore only the bending stress of the end 5a of the spring has to be overcome. At the end of the basic sleeve 1 on the tool side there is provided a protective cap 4 which serves as a stop of the sliding sleeve 2 and moreover constitutes protection against dust. The sliding sleeve 2 is held in a stop position against the protective cap 4 by the compression spring 5 by way of ribs 2a.

The insertion of the tool by introduction of the shaft 13 of the tool into the tool holder is represented in Fig. 1. The shaft 13 of the tool exhibits at its end a chamfer, upon which the inner rounded end of the locking element 3 impinges, whereby the locking element 3 is displaced outwardly against the relatively low spring tension of the soft end 5a of the spring in the aperture 17.

An- 6 As is apparent from Fig. 2, after the shaft of the tool has been fully inserted the groove-shaped recess 15 of the shaft of the tool is located opposite the aperture 17 and the locking element 3 is pressed by low pressure of the soft end 5a of the spring through the oblique bore of the aperture 17 into the groove-shaped recess 15. The locking element 3 consequently secures the shaft 13 of the tool in the tool holder and permits a certain axial movement of the same. Both in the process of tool insertion and also when the tool has been inserted, the sliding sleeve 2 is held in a stop position against the protective cap 4 by the compression spring 5 which apart from its end 5a is as such hard. If with a tool inserted - ie, when the locking element 3 is latched in the groove-shaped recess 15 - an attempt is made to pull the tool out by applying a tractive force to the tool itself, the oblique face 17a of the aperture 17 on the tool side acts as a blocking surface for the locking element 3.

In order to remove the tool, the sliding sleeve 2 must, as represented in Fig. 3, be displaced against the pressure of the conical spring 5 in the direction of the machine, whereby jointly with the compression spring 5 its end 5a is also displaced backwards, said spring pulling the locking element 3 out of the aperture 17 in the process. The front bore of the sliding sleeve 1 is consequently released and the tool can be removed from it by tractive force.

By reason of the differing spring tensions acting on the sliding sleeve 2 on the one hand and on the locking element 3 on the other hand, insertion of the tool is possible without exertion of force, but an unintentional release of the tool as a result of displacement of the sliding sleeve 2 is prevented. The incline of the aperture 17 permits the withdrawal of the locking element 3 by displacing the sliding sleeve 2 and at the same time presents a locking element to prevent the tool from being pulled out when the 7 sliding sleeve 2 is not displaced. The construction of the tool holder according to the invention needs fewer component parts than do tool holders pertaining to the state of the art and also requires substantially less complicated shaping of the individual parts. For instance, no blocking element for the locking element 3 needs to be moulded or mounted on the sliding sleeve 2. Known tools can be used with this tool holder, which at relatively high rotary speeds exhibits only slight imbalance.

The invention is not restricted to the exemplary embodiment illustrated but is also applicable to manual machine tools, in particular drill and/or impact hammers, in which the basic sleeve 1 and the drive member 6 are connected to one another in a different way. For example, it is conceivable for the basic sleeve 1 to be screwed to the drive member 6 or for the basic sleeve 1 to be formed in one piece with the drive member 6. The drive member 6 can then take the form of a hollow cylinder for the purpose of allowing an impact body to pass through. In particular the invention can also find application in the case of combination tool holders which, in addition to the described tool holding device according to the invention for spline- shaft tools, are also provided with a tool holding device for round-shaft tools which takes the form of a jaw chuck.

Am.

8

Claims

1. Tool holder for automatic coupling of impacting and/or rotating tools in manual machine tools, preferably drill andlor impact hammers, with a basic sleeve (1) which on the one hand is connected in non-rotating manner to a drive member (6) of the manual machine tool which transmits the machining motion and on the other hand is designed to receive a shaft (13) of a tool exhibiting at least one groove-shaped recess (15) closed on both sides in the axial direction, in which in each case a locking element (3) arranged displaceably in an aperture (17) of the basic sleeve (1) is capable of engaging, and with a sliding sleeve (2) which is capable of being displaced axially in relation to the basic sleeve (1), said sliding sleeve being pressed by a spring (5) against a stop situated on the end of the tool holder on the tool side, characterised in that the locking element (3) which is capable of being displaced in the aperture (17) is coupled to a free, soft end (5a) of the spring (5) in such a way that it is capable of being set back axially in relation to a partial winding (5b) of the spring (5) which is in contact with the sliding sleeve (2) under the initial stress of the spring (5) when the shaft (13) of the tool is inserted.

2. Tool holder according to Claim 1, characterised in that the aperture (17) of the basic sleeve (1) extends obliquely in relation to the axis of said basic sleeve in the direction of the end of the tool holder on the tool side, approaching said axis.

r 9

3. Tool holder according to Claim 1 or 2, characterised in that the spring (5) is a conical compression spring, the drive-side end of which (5c) that exhibits the smaller diameter is fixed on the basic sleeve (1) preferably in a peripheral groove (18).

4. Tool holder according to Claim 3, characterised in that the peripheral groove (18) is interrupted by an opening (11) in the basic sleeve (1), said opening (11) being provided for the introduction of a connecting element (12) for the connection of the basic sleeve (1) to the drive member (6).

5. Tool holder according to one of the preceding claims, characterised in that on an outer end of the locking element (3) an eye (10) is formed, through which the end (5a) of the spring (5) grips.

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