|Title of Invention||
AN INSERTABLE TOOL FOR ELECTRIC MACHINES
|Abstract||Insertable tool and tool holder for drilling machines, in particular hammer drills, longitudinal webs 6 being located on the core cross-section 1 of the tool shank 11 of an insertable tool, which longitudinal webs 6 perform the function of axial guidance, rotary power transmission and locking in the tool receptacle of the tool holder.|
|Full Text||R. 29 622 27.09.96 Ws/Sh
ROBERT BOSCH GMBH, 70442 Stuttgart
Inaertable tool and tool holder for electric machines having drilling and/or percussion operation
The invention starts from an insartable tool and a tool holder according to the preamble of Claim 1.
DE-43 17 273 Al has already disclosed solutions for improving the rotary driving of insertable tools, in which, in addition to the rotary-driving grooves in the tool shank, rotary-driving strips are also arranged on the periphery of the shank. Although the rotary-driving area is thereby increased and the wear is therefore reduced, the core cross-section of the shank continues to be weakened by the rotary-driving grooves as well as by locking hollows, so that the percussion wave directed into the tool shank by the percussion pin of the machine during percussion operation is not passed to the tool tip in an optimum manner. In addition, notch effects occur at the root of the rotary-driving grooves, which notch effects may lead to the fracture of the shank during high rotary loading or in the event of a rebound blow if a chiselling tool is tilted. Such solutions are therefore sufficiently robust and wear-resistant only for lighter machines and lighter insertable tools.
Furthermore, Swiss Patent 429 630 discloses for large drilling implements a percussion drilling head, attached to the end of a boring rod, as insertable tool, the tool shank of which is designed as a splined shaft, although a chord-like recess- weakening the core of the shank, for accommodating a locking body inserted at the drilling-head holder is provided for the axial locking. This solution also leads to the weakening of the drilling head and to the impairment of the shock waves during operation.
The aim of the present solution is to design the
insertable tools and the tool holder with higher impact
strength and lower wear for mediiim machines.
Advantages of the invention This is achieved by the features in the charac¬terizing part of Claim 1 for insertable tools, with the advantage that a virtually constant system cross-section from percussion pin to the core cross-section of the insertable shank over the sealing and guide region and the drill stem or a chisel diameter permits the undis¬turbed and optimum progression of the blow. The system cross-section is not reduced or weakened at any point. It is merely widened, namely if need be by a striker pin in the implement, by the webs of the insertable shank, if need be by the sealing and guide region, and also by a drill helix. In this case, the longitudinal webs perform the rotary driving, the anti-rotation locking in the event of rebound blows or tilted tool, and the axial locking.
By this construction, the insertion shank of the insertable tool can be realized with substantially higher strength and suitable wear behaviour in existing imple¬ments having a fixed percussion-pin diameter. A circular core cross-section of the insertable tool in the region of its insertion shank ensures the best possible centr¬ing. This centring is a precondition for as true an axial movement as possible - e.g. during chiselling - and for orienting the blow. The axial movement and orientation of the blow is in turn a :!precondition for optimum work progress and thus for the least percussion losses and bending. The avoidance of bending stress reduces the risk of fracture on the one hand and the noise generation on the other hand.
Advantageous further developments and improve¬ments of the features specified in the main c,: aim result from the measures recited in the subclaims. Thus as constant a system cross-section as possible, in particu¬lar in the transition region from the percussion pin to the insertable tool, is esoeciallv advantaaeous for the
undisturbed progression of the percussion waves. There¬fore a section having the true core cross-section of the tool shank for optimum introduction of the blow is provided at the end of the tool shank, before being followed by the region having the longitudinal webs for the rotary driving. Apart from the function of introducing the percussion wave, this rear section is also advantageous for performing the function of guiding the shank. In addition, this section may be made in different lengths or may be completely omitted, in which case it serves as coding for insertable tools which are unsuitable for a percussion operation. The. shortened or omitted section ensures that the percussion pin of the machine no longer strikes the shank of the insertable tool-
The blow proceeds as far as possible undisturbed due Co smooth transitions, e.g. radii or concave shapes, between core cross-section and longitudinal webe or sealing and guide region. The two functions of axial locking and rotary power transmission between tool receptacle and tool shank can be realized in a series arrangement by only one locking element, i.e. if need be only one longitudinal web having a front end face is required for this. This locking element may also be used several times on the periphery in order to be able to insert the insertable tool in a plurality of predeter¬mined positions into a tool holder having only QXXB arrestable locking body. Here, the two functions are arranged axially one behind the other. However, the two functions of axial locking and rotary power transmission may also be arranged next to one another on the shank periphery. In this case, adjacent longitudinal webs without a locking recess lie on both sides next to a locking recess in a longitudinal web or next to a shortened longitudinal web. Thus both functions can be accommodated on a short axial section.
The combination of series and parallel arrange¬ment of the longitudinal webs and the locking elements permits a space-saving arrangement of the functions which
optimally utilizee the insertion shank. The shorter webe permit the axial locking in the same axial section of the tool Bhank/ while directly adjacent longer webs having correspondingly larger flank area are available for the rotary power transmission. Continuous longitudinal webs to the sealing and guide region assist the guidance of the insertable tool, the progression of the blow and, in an overproportional manner, the areal moment of inertia or section modulus and thus the safety against fracture of the tool shank. If the arrangement of the combination of locking and torque tranEmission, on a relatively small periphery section ia selected, this combination can be repeated relatively often over the entire periphery. A small angle of rotation is thereby obtained, which is the maximum angle of rotation required in order to find the correct position for inserting the tool shank in the tool receptacle. For the optimization of the wear, care is to be taken to ensure that the width of the longitudinal webs can be apportioned so as to be more or less the same size in relation to the grooves in between or the inter¬mediate spaces. Insertable tools and tool holder are thereby uniformly loaded and their wear is reduced.
In a tool holder having the characterizing features of Claim 13, it is advantageous that the locking body is arranged between two longitudinal strips behind the front sealing and guide section of the locating sleeve so that said locking body does not engage in the core cross-section of the shank. Furthermore, it is advantageous that the percussion pin of the machine is optimally guided relative to the shank end of the insertable tool in order to be able to direct the per¬cussion waves to the tool tip as far as possible in an undisturbed manner. By the locating of the percussion pin as well as of the shank end in the rear section of the locating bore of the tool holder, an insertion system for the insertable tool and the tool holder is advantageously obtained in which, according to Claim 16, the percussion pin of the tool holder, the shank end, the core cross-section of the insertable tool and its drill stem or its
chisel diameter have a virtuallv constant svston cross-section.
Accordingly, the present invention provides an insertable tool for electric machines, in particular powered hand toots having drilling and/or percussion operation, con^rising a tool shank which can be uisertcd into a respective tool holder of the machine and has means for tlie rotary driving and for the axial locking, the tool shank having an unweakened round core cross-section which extends up to its end face and on the peripliery of whldi a plurality of longitudinally webs are arrai^ed in a symmetric^lty distributed manner, which longitudinal webs are used for the power transmission for the rotary driving or the anti-rotation lodcing and of which at least one has a step for the axial locking, characterized in that adjacent longitudinal webs are of unequal width and/or in that the adjacent intermediate ^aces between the longitudinal webs have a different ofiset
Accordingly, the present invention also provides a tool holder of an electric machine, in particular a powered hand tool having drilling and/or percussion operation, comprising a locating sleeve and a percussion pin for a tool shank of an insertable tool herein described above, w^ierein the front section of the locating sleeve is of smooth dtsign for sealing and guiding, in that the section behind it has a plurality of longimdina! strips, projecting radially inwards, for the rotary driving of the tool, and in that at least one locking body which can be unlocked radially to the outside is arranged over tlie entire width between two adjacent longitudinal strips.
Exemplary embodiments of the invention are shovm in the drawing and described in more detail below. Figure
I shows an insertable tool having a continuous core
cross-section as first exemplary embodiment. Figure 2
shows a drilling tool as second embodiment. Figure 3
shows a chiselling tool as third embodiment, and Figures
4 to 11 show the shank ends of insertable tools as
further embodiments. Figure 12 shows a tool shank suit¬
able for a tool holder according to Figure 13.
Description of the exemplary embodiments
Figure 1 shows in a first exemplary embodiment a percussion drill as insertable tool 2 having a tool shank
II as insertion shank in drilling machines or in particu¬
lar hammer drills. Located on the tool shank 11 are
longitudinal webs 6 which perform the functions of axial
guidance, rotary power transmission and anti-rotation
locking in the event of rebound blows or tilting, and
also axial locking. The rotary driving or anti-rotation
locking is effected via a tool holder (Fig. 13) of the
machine and the blows are executed by a percussion pin 24
which is moved in a reciprocating manner in a driven
spindle sleeve of the machine and is shown separately in
Figure 1. The tool shank 11 has an unweakened core cross-
section 1 of preferably 10 mm diameter extending up to
the shank end. This core cross-section, together with
approximately the same cross-section of the percussion
pin 24 in the implement, of a sealing and guide region 4
and of the drill stem 5 forms an approximately constant
system cross-section. Four longitudinal webs 6 are
arranged in a uni formly di s tributed manner on the core
cross-section 1. The web outer contour 7 preferably has
a diameter oi 14 mm and is designed as a circle element.
The web flanks 12 run inclined relative to one another so
that the longitudinal webs 6 become wider toward the
base, which permits easy release from the die in the case
of a non-cutting manufacturing process. The shape of the
flanks 12 and of the web end faces 8 is curved, e.g. concave, eo that a smooth transition from the core cross-section 1 to the widening by the longitudinal webs 5 is achieved. The transition of the web flanks 12 and of the web end faces to the outer contour may be rounded off or sharp-edged. The shape from one web flank over the intermediate space 15 to the next web flank is of circular or concave design, the web flanks 12 of the adjacent longitudinal webs 6 being connected to one another via a concave region 14 extending up to the core cross-section 1. The insertable tool 2 has a sealing and guide region .4 towards the working region. For an optimum progression of the blow, this region 4 has the same diameter as the core cross-section 1. The longitudinal webs 6 extend in the axial direction of the tool shank. They have a rounded-off rear end face 8b running at an angle and also a front, concave end face 8a towards the tool tip. These end faces 8a serve to axially lock the tool shank 11 for the engagement of a locking body which can be arrested in the tool holder according to Figure 13 of a machine. A region 13 is provided for the axial movement of the tool shank 11 permitted by the locking body, adjoining which region 13 towards the tool tip is the sealing and guide section 4, both sections 4 and 13 having the core cross-section 1 in the present exemplary embodiment. Since the longitudinal webs merge into the core cross-section 1 in front of the shank end, the shank end forms a cylindrical section 3 having the core cross-section 1 of the tool shank 11. Owing to the fact that four identical longitudinal webs 6 distributed uniformly on the periphery have a front, concavely inclined end face Ba, the tool shank 11 can be inserted into a tool holder of the machine and locked therein in four positions offset by 90° each.
Figure 2 shows a furl iier exemplary embodiment of a percussion drill, the diameter of the sealing and guide section 4 being greater than that of the cross-section 1, specifically as large as the outside diameter of the longitudinal webs 6. To form the front, concave end face
■ 8a on two opposite longitudinal webs 6, the latter are provided with a longitudinal recess 13 which extends up to the core cross - section 1 and in which a locking body-in the tool holder of the machine is able to engage in an axially displaceable manner. Two further longitudinal webs 6 are offset therefrom by 9 0°. These further longi¬tudinal webs 6 have no longitudinal recesses for axial locking but run out into the guide section 4 of the tool shank 11. In this solution, the adjacent webs 6 are of unequal width and the adj acent intermediate spaces 15, which are designed as longitudinal grooves between the longitudinal webs 6, have a different offset. Thus the angle a between the two narrower longitudinal webs 6 and the centre of the adjacent intermediate spaces 15 is not 45' as in the case of uniform spacing but is 50" here. Since not all longitudinal webs have a locking function in this case, the different offset of the intermediate space between the longitudinal webs prevents incorrect locking in such a way that an uninterrupted longitudinal web 6 comes to lie in the tool holder in a longitudinal groove having a locking body according to Figure 13.
Figure 3 shows a chisel as insertable tool, in which the longitudinal webs 6 and the shank end 3 are designed in the same way as on the tool shank according to Figure 1. Here, however, the sealing and guide region 4 of the tool shank 11 is larger than the core cross-section 1, and a section 13 for the engagement of a locking body, which section 13 is reduced to the core cross-section 1, is provided between this region 4 and the longitudinal webs 6 over the entire periphery of the tool shank.
Figure 4 shows as a further exemplary embodiment a tool shank 11 of an insertable tool having longitudinal webs 6 designed according to Figure 2 with the difference that here only the top longitudinal web 6 h.'.s a longi¬tudinal recess 13 for the engagement of a locking body. This shank can therefore be inserted only in one position in a tool holder having a locking body according to Figure 13.
Figure 5 shows a further embodiment o£ a tool shank as in Figure 1 with the difference that here two of the four longitudinal webs 6 of the same width are designed to be longer and run out into the core croes-aection 1 only at the sealing and guide region 4. This shank can therefore only be inserted in a tool receptacle in positions offset by 180°.
Figure 6 shows as a further exemplary embodiment a tool shank having only two longitudinal webs 6 which are arranged offset from one another by 180° on the core cross-section 1 of the tool shank.
Figure 7 shows in a further exemplary embodiment a tool shank similar to that in Figure 2, but with the difference that here the longitudinal recesses 13 for the axial locking are made in the centre of the two opposite wider longitudinal webs 6.
Figure 8 shows in accordance with Figure 3 a tool shank in which the rear ends of the longitudinal webs 6 are each of wedge-shaped design in order to facilitate the insertion into the corresponding tool receptacle. In addition, the sealing and guide region 4 here is larger in diameter than that of the core cross-section 1 but not . as large as the outside diameter of the longitudinal webs 6.
Figure 9 shows a tool shank 11 in which two identical longitudinal webs 6 located opposite one another and having one longitudinal recess 13 each are provided on the core cross-section 1 for the axial locking. In addition, two pairs 6a each, located opposite one another, of longitudinal webs 6 are arranged offset therefrom on the core cross-section 1, the pairs 6a being separated from one another by one trapezoidal longitudi¬nal groove 16 each. Here, the sealing and guide region 4 - as in Figure 8 - likewise has a diameter which lies between the core-cross-section diameter and the outside diameter of the longitudinal webs 6.
In the exemplary embodiment according to Figure 10, only the rear section 3 at the end of the tool shank 11 forms the core cross-section 1, whereas the sealing
and guide region as well as the regions of the tool shank between the longitudinal webs 6 have a larger diameter. The guidance of the insertable tool in the tool recep¬tacle of an implement may be effected here over the entire axial length of the tool shank. If this tool shank is manufactured by a forming (non-cutting) process depending on dies, the raw-material diameter is retained for guidance except for the rear end section 3 . The longitudinal webs 6 are formed by material displacement by pressing the longitudinal hollows 15a down to the diameter of the core cross-section 1 on either side of the hollow 15a. The region 4 for sealing and guiding the tool shank is not altered in its geometry by the manufac¬turing process and thus provides the governing initial tolerance. Only the centre region of the tool shank having the longitudinal webs 6 for the rotary power transmission and locking is altered.
Manufacture by a forming process depending on dies is also possible in the case of the tool shanks of Figures 8 and 9, since the webs are configured in such a way that they can be released from a pressing tool, since their flanks have release draft and their ends have no undercuts. The longitudinal webs are configured there in such a way that the tool shank can be worked in a manner rotated relative to the pressing tool in accordance with its spacing during the forming operation, i.e. a die is relocated several times on the periphery of the tool shank in accordance with the spacing frequency, specifi¬cally four times in Figure 8 and once each on each shank half in Figures 9 and 10. There is no flash nor are there release edges on the tool shank in the functional regions for the axial guidance and the rotary power transmission as well as the locking but in the spaces 15 in between. The spaces between the longitudinal webs 6 lie within and the longitudinal webs 6 produced by material displacement lie outside the raw-material diameter, which in the sealing and guide region 4 is retained unchanged. If the tool shanks according to Figures 1 to 7 are manufactured by a cutting process without dies, all snaces 15 between
■ the -longitudinal webs 6 as well as the locking region 13 can be produced with a profile milling cutter starting from the raw-material diameter.
In the embodiment according to Figure 11, the cross-sections of the longitudinal webs 6, in a modifica¬tion of the embodiment according to Figure 7, are no longer of symmetrical design but have an asymmetrical profile. The rotary-driving flank 12a of the longitudinal webs 6 runs approximately radially here, whereas the rear flank 12b, which is not loaded by the rotary driving, runs like a chord. The intermediate spaces 15 between the longitudinal webs 6 are consequently of wedge-shaped design, in which case the radially running flank 12a can optimally receive the rotary-driving torque, and the rear flank 12b, running approximately at right angles thereto, of the adjacent longitudinal web has a considerably larger area so that if need be rebound blows can be absorbed more effectively if a chiselling tool tilts. The transition between the two flanks may be sharp-edged or rounded-off. The asymmetrical flank shape assists the function of torque transmission by permitting a wedge-shaped cross-section for the longitudinal strips which are located in the tool holder and engage in the inter¬mediate spaces 15 of the longitudinal webs 6 of the tool shank 11. Furthermore, tilting during loading of the tool by the torque transmission in addition to the blow is thus prevented- In addition, an asymmetrical flank shape permits efficient production of the tool shank in which the wedge-shaped intermediate spaces 15 permit the use of cylindrical milling cutters having square indexable inserts. The asymmetrical longitudinal webs 6 are designed and optimized for clockwise rotation of the machine. The reverse direction of rotation may be necessary only upon removal of the insertable tool from a drill holt.
A tool shank 11 for locating in a tool holder 20 according to Figure 13 is shown in the exemplary embodi¬ment according to Figure 12. With regard to the design o£ the longitudinal webs 6, the tool shank of the insertable
' tool 3 coresponds to the embodiment according to Figure 9, but with the difference that here the sealing and guide region 4 has a diameter which is equal to the outside diameter of the longitudinal webs 6.
The longitudinal section and cross-section shown in Figure 13 through a tool holder 20 for locating a tool shank according to Figure 12 has a tubular tool recep¬tacle having a locating sleeve 21, the bore diameter of which corresponds in the front region to the diameter of the sealing and guide region 4 of the tool shank 11. In its centre region, the tool receptacle, in accordance with the profile of the tool shank 11 in the region of the longitudinal webs 6, has a corresponding insertion profile recognizable in Figure 13b. There, the inside diameter of the locating sleeve 21 is reduced by the height of longitudinal strips 25, which for the torque transmission project to the inside into the longitudinal grooves 16 and into the intermediate spaces 15 between the web flanks of the longitudinal webs 6 on the tool shank. The clearance dimension between these longitudinal strips 25 produces the inside diameter 22, which corre¬sponds approximately to the core diameter of the tool shank 11. The longitudinal strips 25 are necessary to perform the function of torque transmission and are also used for the axial guidance. The longitudinal strips 25 are designed to be of considerable length in order to offer sufficent area for the torque transmission. The longitudinal strips 25 extend forwards right into the locking region. In order to axially lock the insertable tool, a locking body, e.g. a ball 23, is inserted into an opening in the locating sleeve 21 in the front region between two longitudinal strips 25, which locking body can escape radially outwards upon, insertion of the tool shank and can subsequently be locked by spring force. To remove the tool shank, howev-^r, the locking body must be released manually. This is done by pulling back an actuating sleeve 26 having a ring 27 against the force of a spring 28 which presses the ball 23 into the locking position. Located between the longitudinal strips 2 5 in
the- tool receptacle are grooves which end in the rear section of the tool receptacle at the start of a guide regiipn for the percussion pin 24. The rear section 3 of a tool shank. 11 inserted in the tool holder 20 is also guidad in this region. This region has approximately the diameter of the core cross-section, which in turn corre¬sponds with the dicuneter of the percussion pin 24. However, the insertable tool is guided mainly in the front region of the locating sleeve 21. A sealing lip 2 9 is also attached there to the tool holder 2 0 for sealing against dirt and the like.
The tool holder 20 is detachS-bly fastened to a drive spindle 33 of the machine. By pulling forward a mounting sleeve 30 when the tool holder 20 is being removed, balls 32 can escape outwards behind a retaining ring 31 and thus the tool holder can be released. Auto¬matic locking is effected when the tool holder is pushed onto the drive spindle 33. Since firet of all the tool holder 20 and then the retaining ring 31 of the locking balls 32 reach the latter upon insertion, the balls move outwards into the unlocking position. In this position, when the tool holder 20 is pushed in further, they push back the retaining ring 31 until they move inwards again into the spherical indentations provided for them at the outer periphery of the tool receptacle and come to lie there. The retaining ring 21 then moves by spring force over the locking balls 32 and thus secures the seating of the tool holder on the drive spindle. The actuating sleeve 26 as well as the mounting sleeve 30 can freely rotate so that they stop during operation when touched at the rim despite the rotating tool holder. This means greater safety for the operator, since the machine thereby receives no recoil moment.
An insertion system according to the invention is obtained in the case of a tool shank accordi.-'g to Figure 12 inserted into the tool holder according to Figure 13, the percussion pin 24 in the tool holder 20, the shank end 3, the core cross-section 1 and the drill stem 5 or the chisel diameter of the insertable tool 2 having a
virtually constant system cross-section.
However, the invention is not restricted to the exemplary embodiments shown, since design differences therefrom do not affect the inventive idea, reproduced in Claim 15, of an insertion system for insertable tools. Thus, for example, the web flanks on the tool shank may also be designed radially or asymmetrically relative to one another. The longitudinal webs may constitute a wedge, a quarter circle or a semi-circle for example. The longitudinal webs may also extend obliquely to the axis. A plurality of webs may also be arranged one behind the other or offset from one another in the axial direction. The longitudinal recesses at the longitudinal webs for the axial locking need not be taken up to the core cross-section. The sealing and guide region may also have a greater diameter than the outer contour of the longitudi¬nal webs. Coding of insertable tools may be effected by various lengths of the rear shank end 3. The steps of the sealing and guide regions and of the longitudinal webs to the core cross-section may run conically or even concavely. The longitudinal webs may in turn be provided with longitudinal grooves or the inteirmediate spaces of the longitudinal webs may be provided with further webs. If the percussion-pin diameter of the machine is less than that of the core cross-section at the tool shank, a tapered bevel has to be made on the shank end in such a way that the end-face cross-section of the tool shank is the same as that of the percussion pin. If the longitudinal webs 6 are sufficiently wide, it may be expedient for the longitudinal recesses 13 for the axial locking to extend not over the entire width of the longitudinal webs but only over part of the width. This ensures that at least the torque-transmitting flank of the longitudinal webs is retained even in the region of the longitudinal recess.
1. Aft insertable tool (2) for electric machines, in particular powered hand tools having drilling and/or percussion operation, comprising a tool shank (11) which can be inserted into a respective tool holder (20) of the machine and has means (6, 8) for the rotary driving and for the axial locking, the tool shank (11) having an unweakened round core cross-section (1) which extends up to its end face and on the periphery of which a plurality of longitudinally webs (6) are arranged in a symmetrically distributed manner, which longitudinal webs (6) are used for the power transmission for the rotary dri\'ing or the anti-rotation locking and of which at least one has a step (8a) for the axial locking, characterized in that adjacent longitudinal webs (6) are of unequal width and/or in that the adjacent intennediate spaces (16) between the longitudinal webs (6) have a different offset (a).
2. The insertabie tool according to claim 1, wherein the rear end face (8b) of the longitudinal webs (6) is inclined at an angle, in particular concavely, towards the shank end, and in that the at least one longitudinal web (6) has a front (8a) is inclined at an angle, in particular concavely, and is at a distance (13) from a round sealing and guide section (4), arranged in front of it, of the too! shank (II), which distance (13) is intended for the engagement of a locking body (23) which can be arrested in the tool holder (20) of the machine.
3. The insertabie tool according to claim 1 or 2, wiierein the core cross-section (1) is at least equal to the cross-section of the tool stem (5) of a drilling tool or of a chisel shank, and the cross-section of the guide section (4) is at least as large as the cone cross-section (1).
4. The insertable tool according to any one of the preceding claims, wherein the longitudinal webs (6) merge into the core cross-section (1) in front of a cylindrical section (3) forming the shank end.
5. The insertable tool according to any one of the preceding claims, wherein a plurality of identical longitudinal webs (6) nonuniformly distributed on the periphery have a front end face (8a), inclined at an angle, in particular concavely, such that the tool shank (11) can be inserted mto the tool holder (20) of a machine in only two opposite positions.
6. The insertable tool according to any one of the preceding claims, wherein the diameter ofthe guide section (4) is greater than that of the core cross-section (1), and in that at least some of the longitudinal webs (6) run out into the guide section (4) without an axial locking step (8a).
7. The insertable tool according to any one of the preceding claims, wherein to fonn the front, in particular concave, end face (8a), at least one of the longitudinal webs (6) has a longitudinal recess (13), extending preferably up to the core cross-section (1), such that a locking body (23) in the tool holder (20) of the madune is able to engage therein so that the tool shank (11) can be located in the tool holder (20) in such a way as to be axiaUy displaceable to a limited extent
8. The insertable tool according to any one of the preceding claims, wherein the web flanks (12) of the adjacent longitudinal webs (6) are connected to one another via a concave region (14) extending up to the core cross-sectition (1).
13. The tool holder according to claim 12, wherein the section (21b) having the
longitudinal strips (25) fonns a centre section of the locating sleeve (21), and in that the
rear sectitm (21c) of the locating sleeve (21) is smooth for receiving and guiding the
percussion pin (24) and has approximately the diameter of the core cross-section (1) of
the insertabie tool (2).
14. The tool holder according to claim 12, wherein the diameter of the front section (21b) of the locating sleeve (21) is at least as large as the outside diameter of the longitudinal webs (6) of the insertable tool (2), and in that the shank end (5) of the insertable tool (2) is located and guided in the rear section (21c) of the locating sleeve (21).
15. An insertable tool few electric machines substantially as herein described with reference to the accompanying drawings.
|Indian Patent Application Number||2114/MAS/1996|
|PG Journal Number||30/2009|
|Date of Filing||27-Nov-1996|
|Name of Patentee||ROBERT BOSCH GMBH|
|Applicant Address||P.O. BOX 30 02 20, 70442 STUTTGART|
|PCT International Classification Number||B23B51/08|
|PCT International Application Number||N/A|
|PCT International Filing date|