EP0579579B1 - Tool and chuck for a portable tool - Google Patents

Abstract

The shank (9) of the drill or chisel has two diametrically opposite driving slots (10) with an open end and two diametrically opposite locking slots (11) with both ends closed. To raise the level of torque that can be transmitted to the tool, there are also two diametrically opposite extension slots (12) which lie within the cross-section of the locking slots and extend beyond them. The extension slots are open at the free end of the shank and are engaged by driving keys in the spindle socket. The extension slots are offset by an angle (a) from the axis of symmetry of the locking slots, and the driving flank (12a) is straight and tangential to the curved floor of the locking slot.

Description

The invention relates to a tool for insertion into a tool holder for chiselling and / or impact drilling hand tool devices with a clamping shank, which has at least one axially closed locking groove and at least two axially open rotational driving grooves towards the free end of the clamping shaft.

From DE-PS 25 51 125 tools for hand tools are known, the clamping shank of these tools having one or two axially closed locking grooves and one or two rotational driving grooves open axially towards the free end of the clamping shaft. The tool holder, which serves to hold these tools, has one or two radially displaceable locking elements, which in the present case are designed in the form of balls. Instead of such balls, it is also known to design the locking elements in the form of rollers. The interaction of these locking elements with the axially closed locking grooves results in a positive connection between the tool and the tool holder. By radially disengaging the locking elements, this positive connection can be canceled so that the tools can be removed from the tool holder.

The above-mentioned locking grooves, together with the locking elements interacting with them, are not exposed to particularly high loads, since in operation the tool located in the tool holder is practically floating relative to the locking elements, ie the locking elements cooperate with not to transmit any noteworthy forces to the locking grooves during operation. Only when pulling the tool out of a hole in components are certain axial forces to be transmitted via the locking grooves in cooperation with the locking elements to ensure that the connection between the tool and the tool holder remains.

On the other hand, the turning driver grooves, which are open towards the free end of the clamping shank, and in which corresponding driver bars of the tool holder engage, are subject to extremely high stress. This high stress is due to the torque to be transmitted from the tool holder to the tool. This torque increases, the larger the diameter of the working area for the tools used. Due to the current trend, according to which tools with a larger diameter of the working area are increasingly being used in the hand tool devices, the extraordinarily high torques to be transmitted on the rotary driving grooves cause such signs of wear that the tools fail prematurely. This premature failure in connection with the rotary driving floods can occur significantly before the normal working wear of the working area of the tools.

The attachment of larger rotary driving grooves in order to achieve a larger contact surface which is decisive for the torque transmission fails because the cross-section of the clamping shank is weakened too much, so that a premature failure due to such a cross-sectional weakening is preprogrammed. The arrangement of further rotary driving grooves fails due to space constraints, since part of the surface of the clamping shaft is already occupied by the axially closed locking grooves and further measures on the surface would severely impair the guidance of the tool. A tool known from EP-A 0 355 071 shows a clamping shank, the surface of which is occupied by three axially closed locking grooves. With this known solution, there is only room for a single rotary driving groove, which takes into account the customary dimensional relationships, as well as a further rotating driving groove, which adjoins an interlocking groove on both sides and has a significantly smaller dimension. In this known solution, therefore, a very substantial loss in the size of the possible torque to be transmitted and in guide quality have to be accepted and this due to the locking grooves occupying a substantial part of the surface of the clamping shaft.

The object of the invention is to create a tool which, particularly in cooperation with a suitable tool holder, ensures wear-free transmission of larger torques.

According to the invention, the object is achieved in that at least one longitudinal groove which is open axially to the free end of the clamping shaft is provided, which is arranged in such a way that on the one hand there are unequal distances in circumferential direction from the rotary driving grooves which are adjacent on both sides, and on the other hand that the longitudinal groove and locking groove are in their axial projection below Form a shoulder surface facing away from the rear end face overlap.

According to the embodiment of the tool according to the invention, at least one longitudinal groove open to the free end of the clamping shaft is also available for torque transmission in addition to the rotary driving grooves which are open axially towards the free end of the clamping shaft. The longitudinal groove is arranged in such a way that it neither weakens the clamping shank of the tool nor drastically reduces the surface of the clamping shank used for guiding. Accordingly, no losses with regard to the guidance quality of the tool according to the invention are to be accepted, although the total area of attack that is decisive for the torque transmission is increased considerably.

Due to the overlap of the axial projection of the locking groove and the longitudinal groove designed according to the invention, a shoulder surface facing away from the rear end side is formed, which brings about the axial fixing in cooperation with corresponding locking elements of the tool holder. Since no noteworthy forces are to be transmitted in the axial direction, this shoulder surface is completely sufficient for solving the task assigned to it.

Two longitudinal grooves are preferably provided, the respective axial projections of which overlap the axial projection of two locking grooves each, forming shoulder surfaces facing away from the rear end face. As a result, the total area of application that is decisive for the torque transmission is additionally increased without further weakening the cross section of the clamping shank or without revealing the decisive surface portions of the clamping shank that serve to guide the tool.

It is expedient to arrange the two longitudinal grooves together with the locking grooves, the axial projection of which overlaps the axial projection of the longitudinal grooves, essentially diametrically opposite one another. As a result, a uniform distribution of the forces is achieved and, in addition, advantages are achieved from a manufacturing point of view in that, in the case of non-cutting production, for example by extrusion, the pressing devices can be arranged opposite one another.

From the point of view of the torque load, it has an advantageous effect if the axes of symmetry of the longitudinal grooves are at an acute angle to the axes of symmetry of the locking grooves. In addition to these advantages, such a staggered arrangement also leads to optimal use of the non-overlapping portions of axial projection surfaces as shoulder surfaces for the axial fixation of the tool. This angle can move approximately between 10 and 35 °.

Adequate enlargement of the total engagement surface which is decisive for the torque transmission is achieved above all if the length of the longitudinal grooves exceeds the axial length of the locking grooves on both sides. This longitudinal dimensioning of the longitudinal grooves does not further weaken the cross-section of the clamping shank and furthermore also contributes to optimal guidance behavior.

A weakening of the cross section of the clamping shank is also avoided in particular if the axial projection of the longitudinal grooves is smaller than the axial projection of the locking grooves. Such dimensioning in turn has a positive effect on the formation of the shoulder surface which is decisive for the axial holding of the tool.

Particularly in connection with the avoidance of a weakening of the cross-section of the clamping shank, it is further expedient to arrange the entire axial projection of the longitudinal grooves within the axial projection of the locking grooves.

Insofar as the respective drive-side mouth edges of the longitudinal grooves and locking grooves coincide, there are no deformation jumps which have a detrimental effect on the tool. In addition, training in this regard simplifies the manufacturing process in that the devices required for this can be simplified so that their service life is increased.

From the point of view of torque transmission, optimal conditions are achieved if at least the flank of the longitudinal grooves expediently runs at least in regions essentially radially. The cross section of the longitudinal groove can be of any design, for example in the form of a trapezoid or a triangle. Since the longitudinal grooves penetrate the locking grooves, it is essential that the locking elements also come into contact with the longitudinal grooves. To avoid that on the Transitions between longitudinal grooves and locking grooves form edges that promote wear of the locking elements, preferably at least the flank of the longitudinal grooves on the driving side runs in a straight line and forms a tangent to the bottom of the locking grooves, the bottom of the locking grooves being designed in the form of an arc.

According to a further embodiment of the invention, the flank of the longitudinal grooves on the driving side can be convexly curved and the bottom of the locking grooves can be designed in the form of a circular arc, the arches of longitudinal grooves and locking grooves abutting one another in the overlap region. Even with such a design of the longitudinal groove, deformation cracks which are detrimental to the tool are prevented at most.

From the point of view of avoiding jumps in deformation, an optimal design of the longitudinal grooves also lies in the fact that their flank on the driving side is preferably curved concavely and the base of the locking grooves is designed in the form of a circular arc, the arc of longitudinal grooves and locking grooves also overlapping. In addition to advantages from the point of view of production and wear reduction, this configuration of the longitudinal grooves also leads to a clamping shank that looks optically perfect.

As is known per se, the tools according to the invention can be produced by cutting or non-cutting, for example by means of extrusion molding. In the case of machining, practically any profile of the clamping shank, including the longitudinal grooves, can be produced. In the case of non-cutting production, for example by means of extrusion, it is preferable to ensure that the flank of the longitudinal grooves opposite the flank on the driving side runs in a straight line and forms a positive opening angle with the axis of symmetry of the locking grooves. As a result, from the point of view of feeding the pressing devices, there are no undercuts which lead to disabilities.

In particular from the point of view of the dimensioning of the longitudinal strips interacting with the longitudinal grooves on the tool holder side, it has an advantageous effect if the flank of the longitudinal grooves opposite the driving-side flank is convexly curved. It is advisable to design the formation of this flank symmetrically to the flank on the driving side.

Also from the point of view of the optimal design of the tool bars on the side, interacting with the longitudinal grooves, particularly in terms of strength, the flank of the longitudinal grooves opposite the flank on the driving side is expediently curved. This makes it possible to form both the longitudinal grooves and the tool holder-side, cooperating longitudinal strips as a symmetrical profile if both flanks are concavely curved in the same way.

The tool designed in the manner mentioned above has the advantage that it can be used in a conventional tool holder, for example in accordance with DE-PS 25 51 125. However, this with the loss that higher proportions of torques are not transferable, since the longitudinal grooves remain without function. The advantages according to the invention, i.e. the possibility of increasing the torque to be transmitted, on the other hand, can be exploited if the tool is inserted into a tool holder with a receiving opening which expediently has at least one radially displaceable locking element which interacts with the axially closed locking grooves, with at least two locking bars which cooperate with the rotary driving grooves which are axially open to the free end of the clamping shaft are provided, and at least one longitudinal bar which cooperates with the longitudinal groove which is open axially to the free end of the clamping shaft, the axial projection of which overlaps the axial projection of the region of the respective locking element which projects into the receiving opening and to the has adjacent carrier strips on both sides which are unevenly spaced in the circumferential direction.

The tool holder preferably has two diametrically opposed driver bars, so that the torque to be transmitted is evenly distributed over the tool.

Likewise for the uniform distribution of the torque to be transmitted, two diametrically opposed longitudinal strips are preferably provided. These longitudinal strips are expediently offset with respect to the locking elements in such a way that the axis of symmetry of the longitudinal strips are at an acute angle to the axes of symmetry of the locking elements.

A preferred embodiment of the longitudinal strips consists in that at least their flank on the driving side extends in a convex manner. In particular from the point of view of production, a symmetrical profile of the longitudinal strips brings certain advantages, so that a further preferred embodiment is also distinguished by a convexly curved profile of the flank opposite the flank on the driving side. The arc of both the flank on the entraining side and that of the flank opposite this can essentially correspond to the arc which describes the locking elements, which are preferably designed as balls or cylinders.

Fig. 1

den Einspannschaft eines erfindungsgemässen Werkzeuges in Ansicht;

Fig. 2

einen Schnitt durch den Einspannschaft der Fig. 1 längs der Linie II-II;

Fig. 3

den Einspannschaft eines weiteren erfindungsgemässen Werkzeuges in Ansicht;

Fig. 4

einen Schnitt durch den Einspannschaft der Fig. 3 längs der Linie IV-IV;

Fig. 5

den Einspannschaft eines weiteren erfindungsgemässen Werkzeuges in Ansicht;

Fig. 6

einen Schnitt durch den Einspannschaft der Fig. 5 längs der Linie VI-VI;

Fig. 7

eine schematische Darstellung einer erfindungsgemässen Werkzeugaufnahme im Längsschnitt;

Fig. 8

einen Schnitt durch die Werkzeugaufnahme der Fig. 7 längs der Linie VIII-VIII;

Fig. 9, 10, 11

weitere Ausführungsformen von Einspannschäften jeweils im Schnitt, entsprechend vorangegangener Fig.

The invention is explained in more detail below with reference to the drawings, for example. Show it:

Fig. 1

the clamping shank of a tool according to the invention in view;

Fig. 2

a section through the clamping shaft of Figure 1 along the line II-II.

Fig. 3

the clamping shank of a further tool according to the invention in view;

Fig. 4

a section through the clamping shaft of Figure 3 along the line IV-IV.

Fig. 5

the clamping shank of a further tool according to the invention in view;

Fig. 6

a section through the clamping shaft of Figure 5 along the line VI-VI.

Fig. 7

a schematic representation of an inventive tool holder in longitudinal section;

Fig. 8

a section through the tool holder of Figure 7 along the line VIII-VIII.

9, 10, 11

further embodiments of clamping shafts each in section, corresponding to the previous Fig.

The tool according to FIGS. 1 and 2 has a clamping shank 1. This clamping shaft 1 is provided with two diametrically opposed rotary driving grooves 2, which are open axially towards the free end of the clamping shaft 1. In addition, the clamping shaft 1 is provided with two axially closed locking grooves 3 arranged diametrically opposite one another. Furthermore, a longitudinal groove 4 is provided, which exceeds the length of a locking groove 3 on both sides and the axial projection of the longitudinal groove 4 lies within the axial projection of the one locking groove 3. The area of the locking groove 3 which is not overlapped by the axial projection of the longitudinal groove 4 forms a shoulder surface 3b.

As shown in FIG. 2 in particular, the cross section of the longitudinal groove 4 is essentially V-shaped, the flank 4a of the longitudinal groove 4 on the driving side extending essentially radially and tangentially to the base of the locking groove 3. 2 also shows how the mouth edge 3a of the locking groove 3 coincides with the mouth edge 4b of the longitudinal groove 4.

The tool according to FIGS. 3 and 4 has a clamping shank 5 with two rotational driving grooves 6 which are open axially towards the free end and are diametrically opposite one another. Also diametrically opposite one another, two locking grooves 7 are provided. The length of these locking grooves 7 is traversed by longitudinal grooves 8 likewise arranged diametrically opposite one another with flanks 8a on the driving side. The longitudinal grooves 8 are arranged relative to the locking grooves 7 in such a way that the axial projections of the longitudinal grooves 8 overlap with the axial projections of the locking grooves 7. Shoulder areas 7a are formed by the non-overlapping areas. As shown in FIG. 4 in particular, in this embodiment the axes of symmetry L of the longitudinal grooves 8 run parallel to the axes of symmetry V of the locking grooves 7.

The tool according to FIGS. 5 and 6 has a clamping shaft 9, which is provided with two diametrically opposed rotational driving grooves 10 which are open axially towards the free end of the clamping shaft 9. Furthermore, two diametrically opposed locking grooves 11 are provided, the length of which is exceeded on both sides by two diametrically opposed longitudinal grooves 12. As shown in FIG. 6 in particular, the longitudinal grooves 12 essentially have a trapezoidal profile, the axes of symmetry L of the longitudinal grooves 12 being at an acute angle a to the axes of symmetry V of the locking grooves 11. The flanks of the longitudinal grooves 12 are selected so that the flanks 12a on the driving side essentially form a tangent to the bottom of the locking grooves 11 and the flanks 12b opposite the flanks 12a on the driving side run parallel to the axis of symmetry V of the locking grooves 11. The opening angle of these flanks 12b to the axis of symmetry V of the locking grooves 11 is thus 0 °, that is to say it moves at the lowest limit of its positive opening.

As FIG. 6 also shows, the mouth edges 12c of the longitudinal grooves 12 coincide with the mouth edges 11a of the locking grooves 11. In addition, FIG. 6 shows how the axial projection of the longitudinal grooves 12 lies within the axial projection of the locking grooves 11, so that the non-overlapping regions of the locking grooves 11 form shoulder surfaces 11b.

FIGS. 7 and 8 show, in a simplified representation, part of a tool holder for holding, for example, tools corresponding to FIGS. 5 and 6. The tool holder consists of a guide 13, an actuating sleeve 14 and a cage 15. The guide 13 has two carrier strips which are diametrically opposite one another 13a and two longitudinal strips 13b which are also diametrically opposite one another. According to the tool of FIGS. 5 and 6, the driving strips 13a interact with the rotary driving grooves 10 and the longitudinal strips 13b with the longitudinal grooves 12. To cooperate with the locking grooves 11, for example in the case of a tool according to FIGS. 5 and 6, locking elements 16 in the form of balls are provided, the two of which are diametrically opposite one another. These locking elements 16 are mounted so as to be radially displaceable, passages 13c being provided within the guide 13 for this purpose. By turning or longitudinally displacing the actuating sleeve 14 relative to the guide 13, the locking elements 16 can escape into recesses which are known per se and are not recorded in the drawing, so that they emerge from the clear width of the guide 13 and thus by disengaging 5 and 6 release the clamping shaft 9 for removing the tool.

FIGS. 9 to 11 show further embodiments of tools, each with a clamping shank 17, 21, 25, which is each provided with diametrically opposite rotary driving grooves 18, 22, 26 and also with diametrically opposite locking grooves 19, 23, 27.

The clamping shaft 17 according to FIG. 9 is provided with longitudinal grooves 20, the flank 20a of which on the driving side is bent convexly. As FIG. 9 also shows, the base of the locking grooves 19 is designed in the form of a circular arc, the longitudinal grooves 20 and locking grooves 19 being matched to one another in such a way that the arches abut one another.

Furthermore, FIG. 9 shows how shoulder surfaces 19a are formed by the non-overlapping regions. In addition, it is shown how the flank 20b of the longitudinal grooves 20 opposite the flank 20a on the driving side runs in a straight line, specifically at a positive opening angle b to the axis of symmetry V of the locking grooves 19. This opening angle b can move in the range from 2 ° to 10 °.

The clamping shank 21 according to FIG. 10 has longitudinal grooves 24, whose flank 24a on the driving side is curved in a convex manner analogous to the design according to FIG. 9. In addition, the flank 24b of the longitudinal grooves 24 opposite the flank 24a on the driving side likewise runs convexly, in a manner analogous to the flank 24a on the flanking side. Shoulder surfaces 23a are again formed in the non-overlapping area of locking grooves 23 and longitudinal grooves 24.

11 is provided with longitudinal grooves 28, in which both the flank 28a on the driving side and also the flank 28b opposite this flank 28a has a concave curve. This forms symmetrical longitudinal grooves 28, the axis of symmetry L of which are at an acute angle a to the axis of symmetry V of the locking grooves 27.

As FIG. 11 shows in particular, the flank 28a on the driving side is curved in the same way as the bottom of the locking grooves 27. As a result, the mouth edges 27b of the locking grooves 27 coincide with the mouth edges 28c of the longitudinal grooves 28. 11 in turn shows how stop surfaces 27a are formed in the non-overlapped area of longitudinal grooves 28 and rotary driving grooves 27.

Claims (20)

1. Tool to be inserted in a tool chuck of a hand tool appliance intended for chiselling and/or hammer drilling, with a clamping shank (1, 5, 9, 17, 21, 25) having at least one axially closed locking groove (3, 7, 11, 19, 23, 27) and at least two rotation drive grooves (2, 6, 10, 18, 22, 26) which are open in the axial direction to the free end of the clamping shank (1, 5, 9, 17, 21, 25), characterised in that at least one longitudinal groove (4, 8, 12, 20, 24, 28) is provided which is open in the axial direction to the free end of the clamping shank and which is so arranged that, on the one hand, there is unequal spacing in the peripheral direction from the neighbouring rotation drive grooves (2, 6, 10, 18, 22, 26) on either side, and on the other hand, the longitudinal groove (4, 8, 12, 20, 24, 28) and the locking groove (3, 7, 11, 19, 23, 27) overlap in axial projection with formation of a shoulder surface (3b, 7a, 11b, 19a, 23a, 27a) facing away from the end face behind it.
2. Tool according to claim 1, characterised in that two longitudinal grooves (8, 12, 20, 24, 28) are provided whose respective axial projection overlaps the axial projection of two locking grooves (7, 11, 19, 23, 27) respectively, with formation of shoulder surfaces (7a, 11b, 19a, 23a, 27a) facing away from the end face behind them.
3. Tool according to claim 2, characterised in that the two longitudinal grooves (8, 12, 20, 24, 28) together with the locking grooves (7, 11, 19, 23, 27) whose axial projection overlaps with their axial projection, are arranged substantially diametrically opposite each other.
4. Tool according to one of claims 1 to 3, characterised in that the axes of symmetry (L) of the longitudinal grooves (12, 24, 28) form an acute angle (a) with the axes of symmetry (V) of the locking grooves (11, 23, 27).
5. Tool according to one of claims 1 to 4, characterised in that the length of the longitudinal grooves (4, 8, 12, 20, 24, 28) exceeds on both sides the axial length of the locking grooves (3, 7, 11, 19, 23, 27).
6. Tool according to one of claims 1 to 5, characterised in that the axial projection of the longitudinal grooves (4, 8, 12, 20, 24, 28) is smaller than the axial projection of the locking grooves (3, 7, 11, 19, 23, 27).
7. Tool according to one of claims 1 to 6, characterised in that the entire axial projection of the longitudinal grooves (4, 12, 28) lies within the axial projection of the locking grooves (3, 11, 27).
8. Tool according to one of claims 1 to 7, characterised in that the respective edges (3a, 4b, 11a, 12c, 27b, 28c) at the opening on the drive side of the longitudinal grooves (4, 12, 28) and of the locking grooves (3, 11, 27) coincide.
9. Tool according to one of claims 1 to 8, characterised in that the longitudinal grooves (4, 8, 12, 20, 24, 28) have a flank (4a, 8a, 12a, 20a, 24a, 28a) on the drive side extending substantially radially in at least some regions.
10. Tool according to one of claims 1 to 9, characterised in that at least the flank (4a, 12a) on the drive side of the longitudinal grooves (4, 12) extends rectilinearly and the base of the locking grooves (3, 11) is formed arcuately, the flank (4a, 12a) on the drive side of the longitudinal grooves (4, 12) being tangential to the base of the locking grooves (3, 11).
11. Tool according to one of claims 1 to 9, characterised in that at least the flank (20a, 24a) on the drive side of the longitudinal grooves (20, 24) extends as a convex arc and the base of the locking grooves (19, 23) is formed arcuately, the arc of the longitudinal grooves (20, 24) intersecting the arc of the locking grooves (19, 23).
12. Tool according to one of claims 1 to 9, characterised in that at least the flank (28a) on the drive side of the longitudinal grooves (28) extends as a concave arc and the base of the locking grooves (27) is formed arcuately, the arc of the longitudinal grooves (28) coinciding with the arc of the locking grooves (27).
13. Tool according to one of claims 1 to 12, characterised in that the flank (12b, 20b), which is opposite the flank (12a, 20a) on the drive side of the longitudinal grooves (12, 20), itself extends rectilinearly and forms a positive included angle (b) with the axis of symmetry (V) of the locking grooves (11, 19).
14. Tool according to one of claims 1 to 12, characterised in that the flank (24b), which is opposite the flank (24a) on the drive side of the longitudinal grooves (24), itself extends as a convex arc.
15. Tool according to one of claims 1 to 12, characterised in that the flank (28b), which is opposite the flank (28a) on the drive side of the longitudinal grooves (28), itself extends as a concave arc.
16. Tool chuck with a chuck opening for a tool especially according to one of claims 1 to 15, characterised by at least one radially displaceable locking element (16) for co-operating with axially closed locking grooves, at least two drive ribs (13a) for co-operating with rotation drive grooves which are open in the axial direction to the free end of the clamping shank, and at least one longitudinal rib (13b) for co-operating with a longitudinal groove which is open in the axial direction to the free end of the clamping shank, the axial projection of the longitudinal rib overlapping the axial projection of the part of the respective locking element (16) protruding into the chuck opening, and having unequal spacing in the peripheral direction from the neighbouring rotation drive ribs (13a) on either side.
17. Tool chuck according to claim 16, characterised by two drive ribs (13a) diametrically opposite each other.
18. Tool chuck according to claim 16 or 17, characterised by two longitudinal ribs (13b) diametrically opposite each other.
19. Tool chuck according to one of claims 16 to 18, characterised in that the axes of symmetry of the longitudinal ribs (13b) form an acute angle with the axes of symmetry of the locking elements (16).
20. Tool chuck according to one of claim 16 to 19, characterised in that at least the flank on the drive side of the longitudinal ribs (13b) extends as a convex arc.

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