GB2401817A

GB2401817A - Percussion hand tool having a tool holder clamped within a guide tube

Info

Publication number: GB2401817A
Application number: GB0410708A
Authority: GB
Inventors: Gerhard Meixner
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2003-05-19
Filing date: 2004-05-13
Publication date: 2004-11-24
Anticipated expiration: 2024-05-13
Also published as: DE10322480A1; GB0410708D0; GB2401817B; CN1550295A

Abstract

A hand tool machine, in particular a percussion or drilling hammer, is indicated, comprising a tool holder (10), which has a clamping region for the axially displaceable clamping of the tool (11), and a guide tube (14) for the axial guidance of driving elements (13) acting axially upon the tool (11). In order to achieve an extremely compact design of the tool holder (10) and a short overall axial length of the hand tool machine, the tool holder (10) is accommodated at least by its clamping region in the guide tube (14) and fastened inside the clamping region to the guide tube (14).

Description

R.305683 25.04.2003 ROBERT BOSCH GMBH, 70442 Stuttgart Hand tool machine

Prior art

The invention proceeds from a hand tool machine, in particular a percussion or drilling hammer, according to the preamble of claim 1.

In a known hand tool machine, in particular a drilling or percussion hammer (DE 28 20 128 Al), the tool holder projecting from the machine housing comprises a receiving bush, which has an axially continuous, cylindrical receiving space for the shank of the tool and is formed integrally with an axially non-displaceable rotating sleeve of a rotary actuator, which rotating sleeve is mounted in the machine housing. The receiving bush is mounted axially in front of the guide tube, which guides a driving piston of a percussion mechanism, and the rotating sleeve overlaps the guide tube from the direction of the free end thereof. In the clamping region, which fixes the tool shank, of the tool holder, in which the tool shank is clamped both for rotational driving by the tool holder and for limited axial displacement in order to transmit axial impacts to the drilling point, the receiving bush is provided with radial bores, which are arranged offset by identical angles at circumference relative to one another. Situated in each radial bore is a locking body in the form of a ball, which is capable of engaging into a longitudinal groove with axial stop edges in the tool shank. The receiving bush is overlapped by a displacement sleeve, by means of which the locking bodies are held radially non-displaceably in engagement with the longitudinal grooves. The displacement sleeve has an inner annular groove, into which alter displacement of the displacement sleeve into an unlocking position the locking bodies may engage so that they may move radially out of the longitudinal grooves and release the tool for removal from the tool holder. By means of a spring the displacement sleeve is held in the locking position, in which the tool is locked. To change the tool, the displacement sleeve has to be displaced by hand counter to the restoring force of the spring backwards into its unlocking position.

Advantages of the invention 0 The hand tool machine according to the invention having the features of claim l has the advantage that as a result of consolidating the clamping and fastening region of the tool holder the tool holder is very compact and together with the almost complete insertion of the tool holder into the guide tube an, on the whole, very short overall length of the hand tool machine is achieved. It is thereby possible to reduce both the weight and the cost of manufacture of the hand tool machine.

Advantageous developments and improvements of the hand tool machine indicated in claim l are possible by virtue of the measures outlined in the further 2 0 claims.

According to an advantageous form of construction of the invention, the tool holder comprises a hollow-cylindrical receiving bush, which has an axially continuous, cylindrical receiving space for the tool shank as well as at least one 2 5 axially extending oblong hole penetrating the wall of the receiving bush, a locking body, which is accommodated in an axially and radially displaceable manner in the oblong hole and for engagement into an axially delimited longitudinal groove provided in the tool shank projects partially into the receiving space and is held in a locking position by a locking spring, and a manually releasable blocking apparatus, which prevents radial displacement of the locking body.

According to an advantageous form of construction of the invention, connection means are provided between the receiving bush and the guide tube for the rigid connection of both and are arranged offset by an angle of rotation relative to the at least one oblong hole in the receiving bush.

According to a preferred form of construction of the invention, the connection 0 means comprise at least one radial pin, by which the guide tube is completely and the receiving bush is partially radially penetrated.

Drawings The invention is explained in detail in the following description of an embodiment, which is illustrated in the drawings. The drawings show in each case in a cutout manner: Fig. I to 3 in each case a longitudinal section of a hand tool machine with a tool 2 0 holder in three different insertion positions of the tool, Fig. 4 a longitudinal section, rotated through an angle of rotation of e.g. 45 relative to the longitudinal sections according to Figs. 1 - 3, of the hand tool machine with tool holder.

Description of the embodiment

The hand tool machine, e.g. a percussion hammer, which is illustrated in a cutout manner in longitudinal section in Figs. 1 - 4, comprises a machine housing 12, projecting axially from which is a tool holder 10 for the exchangeable clamping of l a tool 11, e.g. a chisel. The hand tool machine in a known manner has a percussion mechanism for acting axially upon the tool 11 held in the tool holder 10. The percussion mechanism comprises e.g. a wobble mechanism and driving elements, which are guided in an axially displaceable manner in a guide tube 14 accommodated in the machine housing 12. The driving elements comprise a driving piston, which is set in reciprocating axial motion by the wobble mechanism, and a striking piston or punch dolly 13. The driving piston acts via an air cushion upon the punch dolly 13, which in turn delivers the impact energy 0 directly to the tool 11. For building up the air cushion, the punch dolly 13 is sealed off from the guide tube 14 by means of an annular seal IS. Of the driving elements, only the punch dolly 13 may be seen in the cutouts of the hand tool machine illustrated in Figs. 1 - 4. A description of the complete structure of the percussion mechanism is provided in DE 28 20 128 Al. In the construction of the hand tool machine as a drilling hammer, the guide tube 14 is mounted I rotatably in the machine housing 12 and may be set in rotation by a rotary actuator.

The guide tube 14 projects from the end of the machine housing 12 and in its projecting region receives almost the entire tool holder 10. Between the machine housing 12 and the emerging guide tube 14 a dust seal 16 is provided. The tool holder 10 inserted into the guide tube 14 comprises a clamping region for fixing the tool 11 and is fastened inside the clamping region in the guide tube 14, thereby l achieving a compact style of construction of the tool holder 10 and a very short 2 5 overall length of the hand tool machine. The fastening of the tool holder 10 inside the clamping region to the guide tube 14 is illustrated in Fig. 4 and described in detail below. l

The tool holder 10 comprises a hollow-cylindrical receiving bush 17, which is I almost completely inserted into the guide tube 14 and in its short region projecting from the guide tube 14 carries a circumferential annular groove 19, into which a cup-like protective cap 18 made of elastic material is inserted. The protective cap 18 lies against the end of the guide tube 14 and projects beyond the guide tube 14 in a radially outward direction. The protective cap 18 moreover comprises a concentric annular sealing lip 181 which, when the tool holder 10 contains a tool 11, is applied against the tool shank 111 thereof. The hollow-cylindrical receiving bush 17 has an axially continuous cylindrical receiving space 20 for receiving the 0 tool shank 111 of the tool 11, which is guided with slight play in an axially displaceable manner in the receiving space 20. In the clamping region of the tool holder 10, the receiving bush 17 has at least one axially extending oblong hole 21, which penetrates the wall of the receiving bush 17. Preferably two diametrically disposed oblong holes 21 are provided, though the number of oblong holes may be even higher, wherein the oblong holes are arranged offset by identical angles at I circumference relative to one another. In each oblong hole 21 a locking body 22 is accommodated in an axially and radially displaceable manner. Locking body 22 and oblong hole 21 are in said case designed in such a way that the locking I body 22 for engagement into an axially delimited longitudinal groove 23 provided in the tool shank 111 projects partially into the receiving space 20 of the receiving bush 17. The locking body 22 is held by a locking spring 24 situated in the oblong hole 21 in a locking position, in which it lies against the - in the direction of insertion of the tool 11 - front boundary wall 211 of the oblong hole 21. In the -l illustrated embodiment, the locking body 22 takes the form of ball 25 and the locking spring 24 takes the form of leg spring 26, which is supported by its one spring leg against the - in the direction of insertion of the tool 11 - rear boundary wall 212 of the oblong hole 21 and by its other spring leg against the ball 25. The ball 25, the diameter of which is equal to or smaller than the radial depth of the oblong hole 21 and/or the wall thickness of the receiving bush 17, is pressed by the leg spring 26 against the front boundary wall 211 of the oblong hole 21. This position of the locking body 22 or of the ball 25 is the locking position, in which a tool shank 111 inserted into the receiving space 20 is locked in that the locking body 22 or the ball 25 engages into the longitudinal groove 23 in the tool shank 111 (Fig. 3), so that in the tool holder 10 the tool 11 may execute only an axial displacement movement delimited by the length of the longitudinal groove 23. A blocking apparatus 27, in this locking position of the locking body 22 or of the ball 25, prevents radial displacement thereof. In peripheral direction the locking body 22 or the ball 25 engages substantially positively into the longitudinal 0 groove 23 so that, upon rotation of the guide tube 14, the tool holder 10 is driven in the direction of rotation.

Since the receiving bush 17 is almost completely inserted into the guide tube 14, the oblong hole 21 is totally overlapped by the receiving bush 17. In the oblong hole region, the receiving bush 17 is provided with a radial bore 28, which is disposed at or close to the front boundary wall 211 of the oblong hole 21 so that the hole axis of said bore is approximately radially aligned with the axis of the locking body 22 or with the diameter of the ball 25. The blocking apparatus 27 comprises a blocking element 29, which is held displaceably in the radial bore 28 and rests on the locking body 22 or on the ball 25, as well as a sliding sleeve 30, which is held in an axially displaceable manner on the guide tube 14 and overlaps the blocking element 29. In the illustrated embodiment, the blocking element 29 1 takes the form of a straight pin 31, which at each of its two ends has a chamfer 311 and/or 312. The sliding sleeve 30 is held by a restoring spring 33 in the locking position, in which the straight pin 31 resting on the ball 25 prevents radial displacement thereof. By manually retracting the sliding sleeve 30 counter to the restoring force of the restoring spring 33, the sliding sleeve 30 is pulled off the straight pin 31, thereby enabling radial displacement of the straight pin 31. For locking and unlocking the straight pin 31, the sliding sleeve 30 has two axially and radially offset concentric control faces 34, 35, wherein the front control face 34 is at a greater radial distance from the receiving bush 17 than the back control face 35, which is offset axially rearwards. The radial distance of the back control face 35 is selected in such a way that the control face 35 rests directly on the end face of the straight pin 31, which rests on the ball 25. Formed between the radially and axially offset control faces 34, 35 is an oblique face 36, which extends at an acute angle to the guide tube 14. This oblique face 36 together with the chamfer 311 on the straight pin 31 makes it easier to slide the control face 35 onto the straight pin 31. In the illustrated embodiment, the restoring spring 33 takes the form of compression spring 32, which is supported, on the one hand, against a radial shoulder 301 formed in the sliding sleeve 30 and, on the other hand, against a stop 38 fixed in an axially non-displaceable manner on the guide tube 14.

Fig. 4 shows by way of example how the tool holder 10 is fastened in an axially non-displaceable and rotationally fixed manner in the guide tube 14. Fig. 4 in said case shows in a cutout manner a longitudinal section of the tool holder 10 in the same insertion position of the tool shank 111 as in Fig. 1, but offset by an angle of rotation of e.g. 45 relative to the section plane in Fig. 1. In the embodiment of Fig. 4, fastening of the tool holder 10 is effected by means of at least one grub screw 39, which is screwed into mutually aligned bores in the guide tube 14 and in the receiving bush 17. Preferably a plurality of grub screws 39 are used, which are mutually offset in peripheral direction in such a way that there is one grub screw 39 in each annular portion of the receiving bush 17 delimited by two oblong holes 21 in the receiving bush 17. Instead of the grub screws 39 it is possible to use alignment pins, which are pressed into corresponding bores in guide tube 14 and receiving bush 17, wherein the alignment pins fully penetrate the guide tube 14 and only partially penetrate into the receiving bush 17.

In Figs. 1 - 3, the inserting of a tool 11 into the tool holder 10 is illustrated in three different insertion positions of the tool 11. In Fig. 1, the ball 25 is situated in its locking position. The tool 11 inserted in arrow direction 40 according to Fig. 2 bumps against the ball 25 projecting into the receiving space 20 and pushes the ball 25 rearwards, since a radial movement is blocked by the blocking apparatus 27, with simultaneous compression of the leg spring 26. The chamfer 312 on the straight pin 31 then enables a slight radial lift of the ball 25, with the result that the tool shank 111 may be pushed under and past the ball 25. After further insertion of the tool shank 111 in arrow direction 40, the longitudinal groove 23 in the tool shank 111 arrives at a point underneath the ball 25, so that the ball 25 then engages into the longitudinal groove 23. The leg spring 26 is consequently able to convey the ball 25 back into the locking position shown in Fig. 3. The tool 11 now locked in the tool holder 10 may execute only an axial displacement movement, the range of which is defined by the length of the longitudinal groove 23 in the tool shank 111. It is impossible to pull the tool 11 out of the tool holder 10 because the rear boundary edge of the longitudinal groove 23 acts as a stop for the ball 25 and radial displacement of the ball 25 is prevented by the blocking apparatus 27, thereby preventing the rear end of the tool shank 111 from being pulled under and past the ball 25. As is clear from the above description, introduction of the tool 11 is effected simply by inserting the tool shank 111 without having to release the blocking apparatus 27, with the result that single-handed operation is possible.

To remove the tool 11 from the tool holder 10, the sliding sleeve 30 has to be pulled back manually counter to the action of the restoring spring 33, with the result that the control face 35 is pulled off the straight pin 31 and the straight pin moves into the region of the control face 34, where radial displacement of the straight pin 31 is possible. When the tool 11 is then removed from the tool holder 10, the rear end of the tool shank 111 may be pulled through under the ball 25 because the ball 25 is able to yield in radial direction. To remove the tool 11, it is therefore necessary to use both hands.

In the construction of the hand tool machine as a drilling hammer, the guide tube 14 is additionally mounted rotatably in the machine housing 12. A rotary actuator sets the guide tube 14 in rotation, and the receiving bush 17 connected in a rotationally fixed manner to the guide tube 14, via the at least one locking body 22 or ball 25 situated in peripheral direction positively in the oblong hole 21 and in the longitudinal groove 23 of the tool shank 111, drives the tool 11 in the direction 0 of rotation.

Claims

Claims 1. Hand tool machine, in particular a percussion or drilling

hammer, comprising a tool holder (10), which has a clamping region for clamping a tool (11), and comprising a guide tube (14) accommodating driving elements for acting axially upon the tool (11), characterized in that the tool holder (10) is inserted at least by its clamping region into the guide tube (14) and is fastened inside the clamping region to the guide tube (14).

0
2. Hand tool machine according to claim 1, characterized in that the tool holder (10) comprises a hollow-cylindrical receiving bush (17), which has an axially continuous, cylindrical receiving space (20) for receiving a tool shank (111) of the tool (11) as well as at least one axially extending oblong hole (21) penetrating the wall of the receiving bush (17), a locking body (22), which is accommodated in an axially and radially displaceable manner in the oblong hole (21) and for engagement into an axially delimited longitudinal groove (23) provided in the tool shank (111) projects partially into the receiving space (20) and is held in a locking position by a locking spring (24), and a manually releasable blocking apparatus (27), which prevents radial displacement of the locking body (22) in the locking position thereof.
3. Hand tool machine according to claim 2, characterized in that the guide tube (14) completely overlaps the at least one oblong hole (21) and has a radial bore (28), which is associated with the at least one oblong hole (21) and lies radially over the locking body (22) held in locking position, that the blocking apparatus (27) comprises at least one blocking element (29), which is held displaceably in the at least one radial bore (28) and rests on the locking body (22), as well as a sliding sleeve (30), which is seated in an axially displaceable manner on the guide tube (14) and in which two axially mutually offset control faces (34, 35) are formed at a differing radial distance from the guide tube (14) for preventing and enabling the radial displacement of the at least one blocking element (29).
4. Hand tool machine according to claim 3, characterized in that the sliding sleeve (30) is held by a restoring spring (33) in a normal position, in which the control face (35) preventing radial displacement of the at least one blocking element (29) rests on the at least one blocking element (29).
5. Hand tool machine according to claim 4, characterized in that the restoring spring (33) is a compression spring (32), which is supported, on the one hand, against a radial shoulder (301) formed in the sliding sleeve (30) and, on the other hand, against an abutment (38) fixed on the guide tube (14).
6. Hand tool machine according to one of claims 2 - 5, characterized in that the locking spring (24) is situated in the oblong hole (21) and applies the locking body (22) against the, in direction of insertion (40) of the tool (11) into the tool holder (10), front axial boundary wall (211) of the oblong hole (21).
7. Hand tool machine according to claim 6, characterized in that the locking spring (24) is a leg spring (26), one spring leg of which lies against the locking body (22) and the other spring leg of which lies against the, in direction of insertion (40) of the tool (11), rear axial boundary wall (212) of the oblong hole (21).
8. Hand tool machine according to one of claims 4 - 7, characterized in that the locking body (22) is a ball (25) having a diameter equal to or smaller than the wall thickness of the receiving bush (17), and the blocking element (29) is a straight pin (31) having a conical chamfer (312) formed at the ball- side end.
9. Hand tool machine according to claim 8, characterized in that an oblique surface (36) is formed between the radially and axially offset control faces (34, 35) and that the straight pin (31) at its end facing the sliding sleeve (30) has a conical chamfer (31 1).

0
10. Hand tool machine according to one of claims 2 - 9, characterized in that connection means is disposed between the receiving bush (17) and the guide tube (14) for the rigid connection thereof and are arranged offset by an angle of rotation relative to the at least one oblong hole (21) in the receiving bush (17).
11. Hand tool machine according to claim 10, characterized in that the connection means comprise at least one radial pin (39), by which the guide tube (14) is completely and the receiving bush (17) is partially radially penetrated.
12. A hand tool machine substantially as herein described with reference to the accompanying drawings.