EP1694471A1

EP1694471A1 - Drilling hammer and/or percussive hammer having a tool holding fixture

Info

Publication number: EP1694471A1
Application number: EP04820805A
Authority: EP
Inventors: Rudolf Berger; Wolfgang Schmid
Original assignee: Wacker Construction Equipment AG
Current assignee: Wacker Construction Equipment AG
Priority date: 2003-12-19
Filing date: 2004-11-24
Publication date: 2006-08-30
Anticipated expiration: 2024-11-24
Also published as: EP1694471B1; US20070163794A1; JP2007514554A; DE10360008A1; US7661484B2; ES2281028T3; WO2005063450A1; CN1856388A; DE502004003363D1; DE10360008B4; CN100445044C

Abstract

A device for a drilling hammer and/or percussive hammer has a tool holding fixture (21) for holding a tool (22) and for transmitting a torque to the tool (22). A component of the tool holding fixture (21) consists of a hollow cylindrical tool holder (33), which has an insertion opening (34) for an insertion end (30) of the tool, and has an impact opening (35), via which a percussive action can be applied to the insertion end (30). A stopping surface (38), which is stationary with regard to the tool holder (33) and which acts in an axial direction of the tool holder (33), is provided in the tool holder (33) in the area of the impact opening (35). The tool holding fixture is particularly suited for insertion ends (30) according to the SDS-max standard.

Description

Hammer and / or impact hammer with tool holder

According to the preamble of claim 1, the invention relates to a device for a hammer drill and / or impact hammer with a tool holder for holding a tool and transmitting a torque to the tool.

Such a device is used for. B. offered under the brand name "SDS-max" and has proven itself in practice.

Such a device is described in DE 37 16 915 AI. According to this, an impact-drilling tool has at least two rotary driving grooves which open out at the end of the tool shaft and into which web-shaped rotary drivers of a tool holder of the rotary hammer can engage. Furthermore, two recesses which are closed on both sides and diametrically opposite one another are provided in the tool shank, into which locking bodies provided on the tool holder can engage.

The principle of such a known "SDS-max" device is explained in more detail below with reference to FIG. 1. Fig. 1 shows a sectional view of the front, tool holder end of a known hammer and / or hammer.

In the upper half of FIG. 1, a known air spring hammer mechanism is shown in the striking position, while the lower half of FIG. 1 shows the air spring hammer mechanism in the idle position.

Part of the air spring hammer mechanism is a hollow percussion piston 1 which can be reciprocated in a known manner by a drive piston, not shown.

At its front end, the percussion piston 1 strikes an also axially movable striker 2, which in turn transmits the percussion effect at its opposite end to the end face of a not shown insertion end of a tool (for example a drill or a chisel). The insertion end of the tool can be inserted via an insertion opening 3 into an essentially hollow cylindrical recess forming a tool holder 4. At the end of the tool holder 4 opposite the insertion opening 3, a fictitiously defined impact opening 5 is provided, through which the impact effect of the striker 2 can be applied to the insertion end.

The tool holder 4 is part of a tool holder 6, which has three web-shaped rotary drivers 7 formed on the inside of the tool holder 4. The rotary drivers 7 can be inserted into rotary driving grooves (not shown) in the insertion end of the tool, as is the case, for. B. is described in DE 37 16 915 AI. A further rotary driver is arranged opposite the two rotary drivers 7 shown in FIG. 1.

The tool holder 6 also includes two locking bodies 8, which are axially movable in openings 9 of the tool holder 4 and - under certain circumstances explained below - are radially movable.

With the aid of a spring-loaded plate 10, the locking bodies 8 are axially fixed against a guide 11, so that they cannot move radially outward. In this position, they are held in associated locking recesses, not shown, which are present in the insertion end of the tool. The locking recesses in the tool are closed on both sides in the tool shaft in the axial direction, so that a tool insertion end can be prevented by the locking body 8 from being pulled out of the tool holder 4.

However, the operator can move a locking sleeve 12 together with the plate 10 against the action of a spring 13 (to the right in FIG. 1), as a result of which the locking bodies 8 in the openings 9 are also moved to the right. As a result, the locking bodies 8 slide out of their guide 11 and can move radially outwards. In this way, the locking bodies 8 come out of the associated locking recesses, so that the insertion end is freely movable in the axial direction and can be pulled out of the tool holder 4. As explained above, this principle of action is known per se, so that a more detailed explanation is unnecessary.

Even if tools with the brand name "SDSax" have meanwhile developed into a kind of standard, so that the insert ends of the tools can hardly be changed in terms of their design and execution, improvements are possible on the part of the tool holder.

So z. B. for the axial support of the insertion end and for sealing the air spring striking mechanism against the entry of foreign bodies in the striking mechanism area, a striker 2 is always necessary, which transmits the impact effect from the percussion piston 1 to the insertion end. The resulting space requirement is relatively large and limits the design options for the percussion piston 1. So it is not readily possible to change the geometry of the percussion piston 1 in a way that would be desirable for achieving a higher impact energy. In particular with hammers with high impact performance or large torque to be transmitted, there is a risk that the insertion ends, i. H. Knock out the rotary driving grooves in the insertion ends relatively quickly, which can lead to a shortened tool life.

The invention has for its object to provide a device for a hammer and / or percussion hammer with a tool holder for holding a tool and transmitting a torque to the tool, which - with unchanged design of the tool and its insertion end - enables higher impact energies and To transfer torques to the tool without the insert end being stressed or damaged.

The object is achieved by a device according to claim 1. Advantageous further developments of the invention are defined in the dependent claims.

In a device according to the invention, the tool holder has, in a known manner, a tool holder, on the inside of which at least one rotary driver and at least one between a locking device tion state and an unlocking state movable locking body are provided. The tool holder is formed by a substantially hollow cylindrical recess, which has an insertion opening for an insertion end of the preferably non-fret tool on one end side and a striking opening on an opposite end side, through which an impact effect can be applied to the insertion end. According to the invention, a stop surface acting in the axial direction of the tool holder is provided on an inner wall of the tool holder in the region of the impact opening.

The one rotary driver or preferably the two or more rotary drivers can be designed in the form of a web. As an alternative to this, other designs are also possible which allow torque to be transmitted to the tool. In particular, the rotary drivers can also be designed in the form of an internal hexagon into which a hexagonal insertion end can be inserted. The hexagonal surfaces of the rotary drivers interact with the hexagonal surfaces of the insertion end (rotary driving surfaces). It is also possible to turn the rotary driver z. B. to design such that they work together with a spline-shaped insertion end.

In general, corresponding rotary drive surfaces on the insertion end are assigned to the rotary drivers formed on the inside of the tool holder. If - as with the SDS-max system - the rotary drivers are designed in the form of a web, the rotary driving surfaces can be designed in the form of rotary driving grooves in the insertion end.

Even if e.g. B. the insertion end has a hexagonal cross-section and accordingly the tool holder is designed in the form of an internal hexagon, can be spoken of a "hollow cylindrical" recess with respect to the tool holder. The term "hollow cylindrical" is thus not limited to strict inner cylinders, but also includes hollow prismatic shapes, such as. B. the inner hexagon, an inner square, etc.

The stop surface serves as a stop for the insertion end of the tool. Due to the stop surface, it is possible that the insertion end opposite the tool holder in its axial end position, which generally also corresponds to the striking position, can be fixed on one side without any repercussions on the striking system, in particular the air spring hammer mechanism. In the case of previously known solutions, an intermediate striker (see, for example, reference number 2 in FIG. 1) was always required, which not only had to transmit the impact energy to the insertion end, but also served for the axial positioning of the insertion end.

The stop surface according to the invention is completely separate from the function of the impact transmission and serves to support the pressing forces applied by the operator and the relatively weak so-called B-impacts (setbacks of the chisel, especially on hard surfaces).

The provision of the stop surface makes the previously used intermediate striker superfluous, which eliminates the disadvantages caused by it. The sealing of the air spring hammer mechanism, which is normally caused by the intermediate striker, against the ingress of foreign bodies and against uncontrolled lubricant leakage from the hammer mechanism is effectively replaced by a piston piston guide, which is explained in more detail below.

The stop surface is preferably provided in a stationary manner on the inner wall of the hollow cylindrical recess with respect to the tool holder. In particular, the stop surface is formed on the end face of the recess, which also has the impact opening.

In a variant of the invention, the stop surface is also provided on the inner wall of the tool holder. However, it can e.g. B. be made of an elastic material (z. B. plastic or rubber) and thus have a certain elasticity. In another variant, the stop surface z. B. be formed on a sleeve which is axially displaceable on the inner wall of the tool holder against the action of a spring device. Here too, the abutment surface is provided on the inner wall of the tool holder, but strictly speaking it is not stationary. If the description below refers to a “fixed” stop surface, the variants described here of stop surfaces that are movable against an elastic effect should also be expressly included. The movable stop surfaces are at least in the idle state, without being loaded by the insertion end, to be regarded as stationary. Thus, all of the following information regarding stationary stop surfaces applies equally to movable stop surfaces.

In a particularly advantageous embodiment of the invention, the stop surface is conical, so that a frusto-conical insertion bevel formed at the front end of the tool insertion end can rest against it. The insertion end of tools that z. B. are offered under the brand name "SDS-max", usually has a relatively large truncated cone-shaped lead-in chamfer (chamfer) to ensure quick and easy insertion of the insertion end into the tool holder even in rough construction site operation. According to the invention, the conical stop surface in the tool holder is now assigned to this conical surface, which ensures a large-area and thus secure stop.

In a particularly advantageous embodiment of the invention, the rotary driver (s) extend axially on the inside of the tool holder up to the stop surface.

So far, it has been common for the rotary drivers to have only a limited axial extent, which, for. B. correspond to the length shown in Fig. 1 of the openings 9 for the locking body 8. This has not only the disadvantage that due to an increased surface pressure between the rotary drivers and the rotary driving surfaces (rotary driving grooves) z. B. increased wear on the side surfaces of the rotary driving grooves in the insertion ends was found. In addition, with the previous tool holders there is a risk that the insertion ends, which extend far beyond the rotary drivers into the interior of the tool holder, in particular the end face thereof, will be leveled out by the effect of the impact energy, so that the rotary driving surfaces (rotary driving grooves) that run out at the front end of the insertion end be forged or narrowed down. This can have the consequence that the tool can no longer be pulled out of the tool holder, especially if it consists of inferior, too soft material.

The inventive feature that the z. B. web-shaped rotary driver now to the end of the tool holder on the striking mechanism side, that is to say pulled through to the stop surface, prevents such a slamming of the rotary driving surfaces or rotary driving grooves in the insertion end.

With other insertion ends, the z. B. can have a hexagonal cross section, no web-shaped rotary drivers must be present. Rather, the rotary drivers can be configured as surfaces of an internal hexagon, which transmit the torque to the assigned rotary driver surfaces at the insertion end. Here too, however, the rotary drivers are pulled through to the end of the tool holder on the hammer mechanism side.

As already stated, the configuration of the tool holder according to the invention also enables the shape of the percussion piston to be optimized. In a particularly advantageous embodiment of the invention, the percussion piston therefore has a shaft which can be guided in a percussion piston guide. The percussion piston itself can, for. B. be executed solid, a hollow configuration (hollow racket) is also possible.

The percussion piston guide connects directly to the tool holder, so that the stop surface is advantageously arranged at a transition from the percussion piston guide to the tool holder.

With this configuration, the impact energy of the percussion piston can be transmitted directly to the insertion end via its shaft, without an intermediate striker having to be provided, as is the case in the prior art.

In a further development of the invention, the percussion piston guide is hollow-cylindrical and has at least one, but preferably a plurality of tangentially circumferential grooves on the inside. The grooves can be filled with lubricant, in particular grease, during operation of the striking mechanism, on the one hand to ensure adequate lubrication of the percussion piston guide and on the other hand to seal the air spring hammer mechanism against influences which can get into the hammer drill or hammer from the outside via the tool holder. to ensure. The tolerance of the outer diameter of the shaft of the percussion piston and the inner diameter of the percussion piston guide is advantageously selected such that a gap is formed through which lubricant can get from the air spring hammer mechanism into the tool holder. In contrast to the previously used striking tool solutions, this type of percussion piston guidance, due to the very abrupt deceleration of the percussion piston during the stroke, causes grease or dirt particles adhering to the percussion piston shaft to move forward in the direction of the tool holder. In this way, dirt is not only transported out of the area of the air spring hammer mechanism. In addition, the tool holder and the insertion end of the tool are automatically lubricated, so that the previously separate lubrication is no longer necessary. Of course, the gap, ie the tolerance between the percussion piston shaft and the percussion piston guide, should be dimensioned such that only relatively small amounts of fat can escape.

In another further development of the invention, the diameter of the shaft of the percussion piston is smaller than the outside diameter of the insertion end, preferably even smaller than the inside diameter, that is to say the smallest diameter, of the frustoconical insertion bevel of the insertion end. This prevents the plug-in end itself, with its conical insertion bevel, from striking a kind of "mushrooming" in the case of setbacks on the stationary stop surface, by which the racket shaft would be clamped in the worst case.

It is also advantageous if the diameter of the percussion piston shaft is smaller than the diameter of a fictitious cylinder that can be inserted into the interior of the tool holder between the rotary drivers. As a result, the percussion piston shaft can also penetrate into the area of the rotary drivers without touching the rotary drivers or even hitting the rotary drivers.

The described embodiments can also be varied in that an intermediate piston or striker is retained as the striking body, which transmits the impact energy of the striking piston to the insertion end. In this case, the diameter restrictions last described for the percussion piston shaft apply accordingly to the percussion body. per (intermediate piston) or its shaft dimensions. An intermediate piston can e.g. B. in short piston pistons can be advantageous, so that the seal to the striking mechanism is better possible.

The device described is suitable not only for the SDS-max system mentioned, but also for other types of tool holders or tool insertion ends. The tools themselves are often made without a collar that closes the insertion end, which brings cost advantages. Of course, it is also possible to provide the tool with a collar at the end of the insertion end facing the tool tip.

These and other advantages and features of the invention are explained in more detail below using an example with the aid of the accompanying figures. Show it:

1 shows in section a tool holding area of a known tool system (SDS-max);

Figure 2 shows a device according to the invention in a sectional view.

3 shows the device according to the invention in the striking and idling position;

4 shows an enlarged detail of the area of the stop surface from FIG. 3

2 to 4 relate to the same embodiment of the device according to the invention and are described - at least in part - in parallel below.

The device is part of a hammer drill and / or percussion hammer, hereinafter referred to as a hammer, of which, however, only an air spring hammer mechanism 20, a tool holder 21 and part of a tool 22 are shown. The other areas of the hammer are not shown since they do not relate to the invention.

A drive piston 23, which is only partially shown in the figures, is pushed through a drive (motor with crank drive) axially back and forth in a known manner. The percussion piston 24 is also moved axially back and forth via an air spring, not shown, which acts between the drive piston 23 and a percussion piston 24. The percussion piston 24 has a piston plate 25 and a shaft 26 which is axially movably guided in a percussion piston guide 27 held in the hammer. By eliminating an intermediate striker, it is possible to design the percussion piston guide 27 relatively simply as a guide sleeve without having to use several additional components. The shaft 26 strikes an end face 28 of a plug-in end 30 belonging to a tool 29, as z. B. can be seen in the upper part of Fig. 3.

The percussion piston 24 and the percussion piston guide 27 can be rotated together with the tool holder 21, so that they can be driven in rotation by the drive of the hammer. The rotational movement is then transmitted to the tool 22 in order to achieve a drilling effect.

The insertion end 30 is designed according to the well-known standard "SDS-max" and can z. B. also have features described in DE 37 16 915 AI. These include at least two rotary driving grooves, not shown in the figures, which open out at the end of the insertion end 30 belonging to the tool 29, and two locking recesses 31 arranged diametrically opposite one another. A frusto-conical insertion bevel 32 is provided on the end face 28 of the insertion end 30.

The tool holder 21 has an essentially hollow cylindrical recess, which forms a tool holder 33. An insertion opening 34 is provided on an end face of the tool holder 33, through which the insertion end 30 can be inserted in the manner shown in FIGS. 2 and 3. On the end face of the tool holder 33 axially opposite the insertion opening, a striking opening 35 is provided, through which an impact action of the striking piston 24 or the shaft 26 can be applied to the end face 28 of the insertion end.

The impact opening 35 thus forms the transition between the impact piston guide 27 and the tool holder 33. The impact opening 35 must not necessarily be a physically precisely defined characteristic. Rather, it can also be a transition area in which the impact energy of the percussion piston 24 is transmitted to the insertion end 30.

The tool holder 21 furthermore has one or preferably a plurality of web-shaped rotary drivers 36 which extend axially on the inside of the tool holder 33. Two of the rotary drivers 36 can be seen in FIG. 2. The number of rotary drivers 36 is matched to the number of rotary driver grooves, not shown, so that the rotary driver grooves can be pushed onto the rotary driver 36.

Furthermore, the tool holder 21 includes two locking bodies 37, which each engage in the locking recess 31 assigned to them in the insertion end 30, as can be seen in FIGS. 2 and 3.

The principle of locking and unlocking the locking bodies 37 in the locking recesses 31 is known and has already been described above with reference to the prior art. There is therefore no need to repeat this at this point.

A fixed stop surface 38 is provided in the area of the impact opening 35, with reference to the tool holder 33. The stop surface acts at least partially in the axial direction of the tool holder 33 in such a way that the insertion bevel 32 of the insertion end 30 can come to a stop against it, such as, for. B. shown in the upper part of Fig. 3. In this position, the shaft 26 of the percussion piston 24 can optimally hit the end face 28 of the insertion end 30. However, the end face 28 can also be acted upon by the shaft 26 in other positions.

Instead of the stationary stop surface 38, a stop surface that is axially movable relative to the tool holder 33 against the action of a spring device can also be provided in another embodiment of the invention, not shown. So it is z. B. possible to form the stop surface itself by an elastic material (e.g. rubber or plastic). Alternatively, the stop surface can also be provided on a sleeve which is axially movable against the action of a spring device supported on the tool holder. As can be seen from FIG. 2, the web-shaped rotary drivers 36 are brought up to the impact opening 35 or stop surface 38. In this way, torque is always transmitted to the insertion end 30 by the rotary drivers 36 and the rotary driver grooves over a maximum possible length.

The depth of the rotary driving grooves is preferably dimensioned such that the rotating driving grooves run out in the area of the insertion 32 without penetrating the end face 28. This can ensure that even if the end face 28 is at least slightly mushroomed by the impact of the percussion piston 24, the rotary driving grooves are not deformed, so that the tool 22 can be removed from the tool holder 21 at any time.

3 shows the percussion piston 24 and the insertion end 30 in different positions, the normal impact position being shown in the upper part of the figure, in which the percussion piston 24 acts on the end face 28 of the insertion end 30 for transmission of the impact, while the idle position is shown in the lower part of the illustration. in which the insertion end 30 slips out of the housing of the hammer and is only prevented by the locking body 37 from completely sliding out of the housing. The percussion piston 24 has followed the insertion end 30 in the idle position and is in its foremost position. A corresponding design of the air spring percussion mechanism 20 prevents the percussion piston 24 from moving further and from striking the insertion end 30. The configuration of the air spring hammer mechanism 20 required for this is known per se, so that a more detailed description is not necessary at this point.

FIG. 4 shows an enlarged detail of the area around the stop surface 38 of FIG. 3.

The insertion end 30 strikes with its insertion 32 against the stop surface 38. The inside diameter, that is to say the smallest diameter, of the insertion bevel 32 is somewhat smaller than the inside diameter of the stop surface 38. In addition, the diameter of the percussion piston guide 27 is again somewhat smaller than the inside diameter of the stop surface 38. This creates a free area 39 in the material of the insertion end 30 can escape if the end face 28 or the edge running on the inner diameter of the insertion bevel 32 should mushroom somewhat due to the impact of the shaft 26.

A striking surface 40 of the striking piston 24 has a slight curvature which can be seen in FIG. 4, so that the first contact between the striking surface 40 and the end face 28 takes place approximately in the region of the central axis. In this way, a significant part of the impact energy is applied centrally to the insertion end 30. At the same time, undesirable deformations in the edge area, that is to say on the insertion slope 32, are avoided.

The diameter of the shaft 26 of the percussion piston 24 can be somewhat smaller than the inside diameter of the insertion bevel 32 of the insertion end 30.

The special design of the tool holder 33 enables the insertion end 30 to be guided radially over its entire insertion length inserted into the tool holder 33. The wear of the insertion end 30 can thereby be significantly reduced. Because the web-shaped rotary drivers 36 only run out in the area of the stop surface 38, it is not necessary to provide diameter enlargements of the tool holder 33 in front of and behind the rotary drivers. B. could start and clear a broach. Such a requirement exists with the shorter rotary drivers of the prior art, where the insertion end can only be guided in the area of the rotary drivers. Due to the fact that, according to the invention, the rotary drivers have a substantially greater axial extent, the radial insertion of the insertion end 30 can also take place over a longer area.

The invention enables the use of already known tools with insertion ends according to the "SDS-max" standard, even for devices with significantly higher performance. If the "SDS-max" standard previously used were also maintained in the case of such devices on the tool holder side, the insertion ends of the tools would be destroyed after a very short time. Of course, the invention can also be used advantageously with plug-in systems other than the "SDS-max" standard.

Claims

1 patent claims

1. Device for a hammer drill and / or percussion hammer with a tool holder (21) for holding a tool (22) and transferring one

, 5 torques on the tool (22), the tool holder (21) having: an essentially hollow-cylindrical recess forming a tool holder (33) and having an insertion opening (34) on one end through which an insertion end (30 ) of the tool (22), 0 and which has an impact opening (35) on an opposite end through which an impact effect can be applied to the insertion end (30), at least one rotary driver (36) formed on an inside of the tool holder (33) ), and5 - at least one locking body (37) which is held in a locking state in a predetermined radial position and can be moved at least radially from the predetermined radial position in an unlocking state, characterized in that on an inner wall of the tool holder opening (33) A stop surface (38) acting in the axial direction of the tool holder (33) is provided in the region of the impact opening (35) is.

2. Device according to claim 1, characterized in that the stop surface (38) is conical. 3. The device according to claim 1 or 2, characterized in that the tool (22) has: + the insertion end (30), which is essentially cylindrical and is formed by a tool shaft, 0 + at least one on the insertion end (30) trained rotary driving surface which opens out at the end of the tool shaft, and + at least one locking recess (31) formed in the insertion end (30) and closed on both sides in the axial direction of the tool shaft; 5 - the rotary driver (36) is assigned to the rotary driver surface and is designed such that the rotary driver surface can be pushed onto the rotary driver (36) when the tool (22) is inserted, 1 - the at least one locking recess (31) is associated with the at least one locking body (37) which is held in the locking state in the locking recess (31) and in the unlocking state at least radially from the locking recess

, 5 (31) is movable, and that the stop surface (38) serves as a stop surface for the insertion end (30).

4. Device according to one of claims 1 to 3, characterized in that at the front end (28) of the insertion end (30) a truncated cone-shaped chamfer (32) is provided.

5. Device according to one of claims 1 to 4, characterized in that the rotary driver (36) extends axially on the inside of the tool holder 5 (33) up to the stop surface (38).

6. Device according to one of claims 1 to 5, characterized in that the insertion end (30) is guided radially over its entire insertion length inserted into the tool holder (33)

7. Device according to one of claims 1 to 6, characterized in that an air spring hammer mechanism (20) is provided in the hammer drill and / or percussion hammer, with a drive piston that can be moved back and forth by a drive and a drive piston that can be driven by the drive piston Percussion piston (24), the percussion piston (24) has a shaft (26) which can be guided in a percussion piston guide (27), and that the stop surface (38) at a transition from the percussion piston guide (27) to the tool holder ( 33) is arranged.

8. The device according to claim 7, characterized in that the impact energy of the percussion piston (24) via its shaft (26) can be transmitted directly to the insertion end (30). 5

9. The device according to claim 7 or 8, characterized in that the percussion piston guide (27) is hollow cylindrical and we- 1 at least has a tangential circumferential groove on the inside.

10. The device according to one of claims 7 to 9, characterized in that the tolerance of the outer diameter of the shaft (26) of the _5 percussion piston (24) and the inner diameter of the percussion piston guide (27) are selected such that a gap is formed through which Lubricant can get into the tool holder (33) from an area of the air spring hammer mechanism (20). 0

11. The device according to one of claims 7 to 10, characterized in that the diameter of the shaft (26) of the percussion piston (24) or one of the impact energy of the percussion piston (24) on the insertion end (30) transmitting percussion body is smaller than the outer diameter of the Inserting (30) .5

12. Device according to one of claims 7 to 11, characterized in that the diameter of the shaft (26) of the percussion piston (24) or an impact body transmitting the impact energy of the percussion piston (24) to the insertion end (30) is smaller than the inner diameter of the frusto-conical insertion bevel (32) of the insertion end (30).

13. Device according to one of claims 7 to 12, characterized in that the diameter of the shaft (26) of the percussion piston (24) or of an impact body transmitting the impact energy of the percussion piston (24) to the insertion end 5 (30) is smaller than the diameter of a fictitious, in the interior in the tool holder (33) between the or the rotary driver (36) insertable cylinder.

14. Device according to one of claims 1 to 13, characterized in that the stop surface (38) is stationary with respect to the tool holder (33).

5