Quick-change attachment and machine tool system with a quick-change attachment

Abstract

Quick-change attachment (10) for a machine tool (100), comprising a first coupling section (20) which can be coupled to the machine tool (100), a second receiving section (40) which can be coupled to a tool, and a damping section (60) arranged between the coupling section (20) and the receiving section (40), wherein the coupling section (20) comprises a coupling mechanism (22) which is designed for releasable coupling to a drivable drive spindle (102) of the machine tool (100) in such a way that a torque about a longitudinal axis (L 100) of the drive spindle (102) can be transferred from the drive spindle (102) to the coupling section (20), and wherein the receiving section (40) has at least one receiving geometry for releasably receiving the tool and at least one connecting geometry for transmitting torque from at least one corresponding counter-connecting geometry on the coupling section (20) to the connecting geometry of the receiving section (40), characterized in that the damping section (60) comprises at least one damping element (62) which is arranged between the connecting geometry and the counter-connecting geometry for damped torque transmission from the coupling section (20) to the receiving section (40) or from the receiving section (40) to the coupling section (20) in such a way thatthat the transmission of the torque from the mating connection geometry or the connection geometry via the damping element (62) to the respective other connection geometry or mating connection geometry in the direction of the torque to be transmitted can be carried out in a form-fitting manner, wherein the connected components, the mating connection geometry of the coupling section (20), the damping element (62) and the connection geometry of the receiving section (40), are supported on one another in the direction of the torque damped by the damping element (62) and thus in the circumferential direction, whereby the damping element (62) is not subjected to any shear stress.

Description

[0001] The invention relates to a quick-change attachment for a driven machine tool and to a machine tool system with a quick-change attachment that can be coupled to a machine tool.

[0002] Interchangeable tool holders for machine tools are known from the prior art. These are intended to enable tools of different sizes to be coupled to a drivable drive spindle of a machine tool by quickly changing the tool holder (quick change). Even with an adaptive chuck as the tool holder, the holding area may be too small for tools with large diameters, such as drilling tools. Furthermore, if multiple back-and-forth changes between multiple tools are required, it may be easier and faster for the user to change the chucks with the tool clamped in place than to open one chuck each time to swap one tool for another and then close the chuck again.

[0003] Accordingly, DE 10 2007 028 486 A1 discloses a tool holder for a power tool with a locking device that enables quick changes and is also intended to be suitable for absorbing the high forces that occur, for example, during impact operation of a hammer drill, and to ensure secure locking. For this purpose, two elastic elements are provided that are arranged between individual components of the locking device and dampen shocks and vibrations in the axial direction.

[0004] Another solution is shown in WO 2016 / 074 901 A1, in which a damping element is arranged between the base body of a collet and the chuck, connecting them in a material-to-material bond. In this way, the damping element acts in both the axial and radial directions. Since the material-to-material bond between the base body and the collet represents the only connection between the two components, the entire torque must be transmitted via the material bond. During operation, the damping element is subject to high shear forces, which significantly reduce the service life of the damping element and thus the collet.

[0005] Another solution is known from DE 40 19 727 A1. This document discloses a chuck consisting of three main parts: a tool adapter ring with a threaded stud for the tool; a collar; and a housing sleeve. The chuck slides onto the drill spindle, which has slots for torque drive through radial pins and a V-side groove for axial locking by balls. To disengage the coupling from the spindle, the housing sleeve is rotated to allow the balls to move into the pockets in the retaining ring. The end faces of the tool adapter ring and the housing sleeve have mating cam surfaces that cause the inner bands of the adapter ring to be pressed onto the outer bands of the collar. This closes the collar when the housing is rotated on the machine spindle, eliminating any play between the spindle and chuck.

[0006] In contrast, it is an object of the present invention to provide a quick-change attachment which uses the advantages of damping known from the prior art and at the same time at least reduces the known disadvantages.

[0007] To this end, the invention proposes a quick-change attachment for a machine tool having the features of claim 1 and a machine tool system having the features of claim 9, comprising a first coupling section which can be coupled to a machine tool, a second receiving section which can be coupled to a tool, and a damping section arranged between the coupling section and the receiving section, wherein the coupling section comprises a coupling mechanism which is designed for releasable coupling to a drivable drive spindle of the machine tool, such that a torque about a longitudinal axis of the drive spindle can be transmitted from the drive spindle to the coupling section,and wherein the receiving section has at least one receiving geometry for releasably receiving a tool, as well as at least one connecting geometry for transmitting torque from at least one corresponding mating connection geometry on the coupling section to the connecting geometry of the receiving section. The damping section comprises at least one damping element arranged between the connecting geometry and the mating connection geometry for dampened torque transmission from the coupling section to the receiving section and / or from the receiving section to the coupling section such that the transmission of torque from the mating connection geometry or the connecting geometry via the damping element to the respective other connection geometry or mating connection geometry can take place in a form-fitting manner in the direction of the torque to be transmitted.

[0008] The torque to be transmitted can be the torque of the drive spindle of a connected machine tool. Furthermore, it can also be the torque that is introduced into the machine via the tool when the tool is slowed down by increased resistance (braking torque or braking torque). The latter in particular can damage the machine if it is transmitted undamped from the connection geometry of the receiving section to the mating connection geometry of the coupling section and is thus introduced into the machine's drive train via the connected drive spindle of the machine tool. However, damping of the drive torque can also be advantageous, in particular to compensate for sudden changes in the speed. According to the invention, both unidirectional damping in only one direction of rotation, i.e.of the drive torque or the braking torque, or bidirectional damping in both directions of rotation can be provided by the damping element.

[0009] The resulting positive connection has the advantage that the connected components support each other in the direction of the torque dampened by the damping element, i.e., in the circumferential direction, thus preventing the damping element from experiencing shear stress. This significantly increases the service life of a damping element made of an elastomeric material and ensures reliable torque transmission.

[0010] In general, positive-locking connections are created by the interlocking of at least two connection partners, in this case the connection geometry and the counter-connection geometry with the damping element arranged in between. By supporting the connection geometry via the damping element on the counter-connection geometry, one connection partner in the form-locking connection is in the way of the other, which results in the drive in the direction of the torque. Under operating load, compressive forces, i.e. the circumferential forces, act perpendicular to the surfaces of the respective connection partners. Since the damping element is arranged between the connection geometry and the counter-connection geometry, the circumferential forces do not act tangentially on it, as for example in the solution of WO 2016 / 074901 A1, but perpendicularly, which reduces the load on the damping element and can achieve improved damping.Furthermore, the torque to be transmitted itself can be dampened, not only occurring shock loads in the axial direction, as for example in the solution of DE 10 2007 028 486 A1.

[0011] The machine tool can be any type of machine tool with a rotary drive spindle or spindles, for example screwdrivers, drills, hammer drills, but also grinders of all kinds and the like.

[0012] It is well known, particularly in connection with screwdrivers, that they are exposed to high mechanical loads in so-called hard screwdriving applications. This occurs when a screw is initially screwed into a pre-fabricated thread (for example in a steel component) with little resistance, but is then suddenly braked when the screw head comes to rest on the surface. This braking impulse is transmitted to the gearbox in milliseconds or nanoseconds, depending on the rigidity of the system, and can damage or even destroy it. Due to the high speed at which such an event occurs, an electrical shutdown to protect the machine is not an option. It is precisely in such cases that damping of the torque or a counter torque (braking torque) is essential to protect both the machine and the user.Operating situations are also known with other machines in which the machine tool is suddenly braked, with the same negative consequences for the machine, but also for the user, who can consequently be exposed to a strong kickback moment from the machine.

[0013] The drive spindle of the machine tool, which drives a connectable tool, extends along a longitudinal axis and rotates about this same longitudinal axis. Similarly, the quick-change attachment extends along a longitudinal axis, which, when attached to a machine tool, can be coaxial with the longitudinal axis of the output spindle. Terms such as "axial" or "radial" therefore refer to the longitudinal axis of the machine tool's drive spindle or, analogously, to the longitudinal axis of the quick-change attachment. The proximal end of the quick-change attachment comprises the coupling section, while the distal end comprises the receiving section.

[0014] Furthermore, it can be provided that the at least one damping element is arranged interchangeably between the connecting geometry and the counter-connecting geometry and is made in particular from an elastic material. This interchangeability can also ensure that the quick-change attachment remains usable by replacing the damping element if the damping effect decreases after a longer period of operation, for example because the material has fatigued. Unlike in the prior art, the damping element is not injected between the components, but is manufactured as a separate component from an elastic material and inserted accordingly between the aforementioned components during assembly. Elastomers, plastic elastomers, thermoplastics or thermosets can be considered as elastic materials, as can resilient metallic materials.

[0015] Furthermore, it can be provided that the at least one damping element is substantially annular and comprises at least one damping projection which extends in the axial direction between the connection geometry and the counter-connection geometry.

[0016] The annular design allows parts of the quick-change extension, as well as, for example, a connected drive spindle of a machine tool, to extend through the central recess. The damping element can have one or more projections, depending on the design of the connecting geometry and the mating connecting geometry. In particular, a damping projection can be provided between each connecting surface of the connecting geometry and each adjacent connecting surface of the mating connecting geometry. Alternatively, it is also possible for torque to be damped in only one direction of rotation. In this case, the connecting surfaces of the connecting geometry and the mating connecting geometry can alternately abut one another or accommodate part of the damping element between them.

[0017] Furthermore, regardless of the design of the damping element but also in combination with the embodiments described above, it can be provided that the receiving geometry of the receiving section for releasably receiving a tool comprises at least one outer receiving geometry, in particular an external square, onto which a tool can be plugged in sections, and at least one inner receiving geometry, in particular a hexagon socket, into which a tool can be plugged in sections, at a free end of the receiving section. This design makes the quick-change extension additionally adaptive and can accommodate different types of tools. Both the outer receiving geometry and the inner receiving geometry can comprise different geometries in the axial direction, in particular different diameters and polygon cross-sections, which are arranged one after the other.In the simplest case, however, a single outer mounting geometry and a single inner mounting geometry are provided. A socket, for example, can be mounted on an external square, as a possible example of an external mounting geometry, which in turn enables a wide range of applications and tool coupling. A hexagon bit, for example, can be inserted into the internal hexagon, as a possible example of an internal mounting geometry.

[0018] Furthermore, it can be provided that the connection geometry and the counter-connection geometry each have at least one connection projection, wherein the connection projections are arranged relative to one another in such a way that a torque can be transmitted in the radial direction from the connection projection of the counter-connection geometry via the damping section, in particular the damping projection of the damping section, to the connection projection of the connection geometry. Analogously, in the event of a hard screw connection or a similar event, a braking torque can be transmitted in the radial direction from the tool via the connection projection of the connection geometry to the damping element, in particular the damping projection, and from there, in a damped manner, to the connection projection of the counter-connection geometry.

[0019] Furthermore, it can be provided that the connecting projections are tooth-shaped or wing-shaped and that the space between the at least one connecting projection of the connecting geometry and the at least one connecting projection of the counter-connecting geometry is filled by the damping element in order to enable a damped transmission of the torque with almost no play.

[0020] In addition, independently of the previously described embodiments but also in combination with these, it can be provided that the coupling mechanism for releasably coupling to a driven drive spindle of the machine tool has a coupling sleeve with at least one coupling recess and an actuating sleeve which at least partially surrounds the coupling sleeve and which can be rotated in the circumferential direction relative to the coupling sleeve, as well as at least one coupling element which is received in a space between the actuating sleeve and the coupling sleeve and can perform a radial relative movement to the coupling sleeve as a result of a relative rotational movement of the actuating sleeve in order to bring the at least one coupling element into positive engagement with an engagement structure of the drive spindle of a machine tool through the at least one coupling recess.

[0021] The at least one coupling element can be designed, for example, as a ball or bolt, which can engage through a corresponding coupling recess in a corresponding engagement structure, for example a corresponding recess or bore on the drive spindle of the machine tool, and can thereby positively lock this against loosening both in the axial direction and in the circumferential direction. In this position of the coupling element, the actuating sleeve is in a locked position relative to the coupling sleeve and holds the coupling element in its engaged position in the radial direction. When the actuating sleeve is actuated from the locked position to a release position, the at least one coupling element can move radially out of the engagement structure, thereby releasing the positive locking. The quick-change attachment can be easily removed by the user.

[0022] For particularly simple and quick changing of the quick-change attachment and secure fixation, the actuating sleeve can be preloaded by a spring element toward a relative position, in particular toward the locking position, in which the coupling element can be in positive engagement with an engagement structure of the drive spindle of a machine tool through the at least one coupling recess. To change, the actuating sleeve is rotated out of its preloaded position; otherwise, it is returned to the locking position by the spring element and remains in the securing locking position due to the preload.

[0023] Additionally, terms such as "comprising," "having," or "with" do not exclude other features or steps. Furthermore, terms such as "a" or "the," which refer to a singular number of steps or features, do not exclude a plurality of features or steps, and vice versa.

[0024] Further features and advantages of the invention will become apparent from the following description of an embodiment of the invention and from the subclaims.

[0025] The invention is described in more detail below with reference to the accompanying figures. The figures show several features of the invention in combination with one another. Of course, however, a person skilled in the art can also consider these features separately and, if necessary, combine them into further useful sub-combinations without requiring inventive activity.

[0026] They show schematically: Fig. 1 shows a section of a machine tool system according to the invention with a machine tool and a quick-change attachment; Fig. 2 a longitudinal section of the quick-change attachment of the Fig. 1; Fig. 3A is an isometric view of the quick change attachment of the Fig. 1 and Fig. 2; Fig. 3B of an exploded view of the quick change attachment of the Fig. 1 to 3A; and Fig. 3C isometric views of the quick change attachment components of the Fig. 1 to 3B.

[0027] The figures show an embodiment of the present invention in which the machine tool of the machine tool system is designed as a screwdriver. The machine tool system is generally designated by the reference numeral 1000 and comprises, in addition to a machine tool 100, one or more (only one is shown) quick-change attachments 10 that can be attached to a drivable drive spindle 102 of the machine tool.

[0028] As in the Fig. 1, the drive spindle 102 has a receiving recess 108 with a hexagon socket at its free end for receiving a tool. Furthermore, receiving recesses 104 are provided on the outer surface of the drive spindle 102 in its end region, which are connected to one another via a circumferential annular groove 106. The annular groove 106 is radially oriented (relative to the longitudinal axis L 100 the drive spindle 102) is less deep than the receiving recesses 104.

[0029] The receiving recesses 104 form an engagement structure of the drive spindle 102 both for coupling tools and for the coupling quick-change attachment 10, as described below with reference to the Fig. 2 explained.

[0030] The quick-change attachment 10 extends along a longitudinal axis L 10 which, in a state coupled to the drive spindle 102 of the machine tool 100, is coaxial with the longitudinal axis L 100 It comprises a coupling section 20, a receiving section 40 and a damping section 60 (cf. Fig. 3A). The coupling section 20 serves for coupling with the drive spindle 102 by means of a coupling mechanism 22 (see Fig. 2).

[0031] The coupling mechanism 22 comprises an actuating sleeve 24 for manual actuation by a user, a coupling sleeve 26 coaxially received therein, which can be plugged onto the free end of the drive spindle 102 and receives it in its receptacle 38b, as well as coupling elements 28, in the embodiment shown designed as balls. Fig. 2, the coupling mechanism is shown in the locked position of the actuating sleeve 24, in which a radially inwardly projecting guide slot 26a holds the balls in an engaged position in which they penetrate coupling recesses 30 on the coupling sleeve 26 and engage in the receiving recesses 104 of the drive spindle 102. This engagement achieves a positive connection that secures the quick-change attachment 10 both against an axial relative movement of the drive spindle 102 and against a relative rotation of the drive spindle 102 relative to the coupling sleeve 26. The actuating sleeve 24 is preloaded in the shown locked position by means of a spring element 32 and is returned to the locked position by this element after an actuating movement by the user.

[0032] As a result of a rotational movement of the actuating sleeve 24 from the locking position into a release position (not shown), the radial extension of the guide slot 26a changes in the direction of the longitudinal axis L in the contact area of the guide slot 26a on the balls. 100 such that the balls can move radially outward and thereby disengage from the receiving recesses 104 of the drive spindle. In this release position of the actuating sleeve 24, the quick-change attachment can be detached from the drive spindle 102 or simply pushed onto it. As soon as the user releases the actuating sleeve 24, it is returned to the locked position. Depending on the choice of spring element 32 and in particular the spring strength, the quick-change attachment can also be pushed onto the drive spindle 102 without manually actuating the actuating sleeve 24. The chamfer in the area of the free end of the drive spindle 102 provides support in this process.

[0033] At its end facing away from the receptacle 38b, the coupling section 20 has a counter-connection structure in the form of a plurality of wing-shaped connecting projections 34, which are provided for transmitting a torque from the coupled drive spindle 102 to a tool (not shown) that can be received on the receiving section 40.

[0034] An essential aspect of the present invention lies in the damped transmission of the torque via the damping section 60, which will be discussed in detail later.

[0035] The receiving section 40 comprises both a connecting structure corresponding to the counter-connecting structure with connecting projections 54 which protrude from a contact disc 50 and with a central bearing shaft 52 which is rotatably supported in a receptacle 38a of the coupling section 20, as well as at least one receiving geometry (in the embodiment shown, two receiving geometries 44 and 46) for receiving a tool (not shown).

[0036] The receiving geometries comprise an outer receiving geometry, in the embodiment shown, for example, designed as an external square 44 with an optional annular groove 48, onto which a tool, for example a socket, can be inserted in sections, and an inner receiving geometry, in the embodiment shown, for example, designed as a hexagon socket 46, into which a tool, for example a hexagon bit, can be inserted in sections.

[0037] The aforementioned damping section 60 enables a damped transmission of torque from the coupling section 20 to the receiving section 40 and vice versa. For this purpose, it comprises a damping element 62, which in the embodiment shown is annular and has an internal recess 68 through which both a section of the coupling section 20 and a part of the receiving section received therein, namely the bearing shaft 52, can extend.

[0038] Furthermore, the damping element has a plurality of damping projections 64 which, in an assembled state of the quick-change attachment, are each arranged between a connecting projection 54 of the connecting geometry and a connecting projection 34 of the counter-connecting geometry or extend between them (cf. Fig. 3A). The damping projections are dimensioned such that the contact surfaces 66 each directly abut the contact surfaces 56 and 36 of the adjacent connecting projections 34 and 54, in order to enable a virtually backlash-free torque transmission.

[0039] Due to the specific design and arrangement of the damping projections 66, which form a positive connection with the connecting projections 34 and 54, a torque or the circumferential forces can be transmitted perpendicularly to the contact surfaces 36, 66, 56, whereby no shear forces act on the damping projections 66. Furthermore, the design of the damping projections 66 on the annular damping element 62 enables the integral formation of several damping projections 66 with defined distances from one another.

[0040] The damping element 62 is made as a separate component from an elastic material, for example from an elastomer, plastic elastomer, thermoplastic, thermoset or the like, or from a resilient metallic material.

[0041] During assembly, the damping element 62 is first pushed over the coupling sleeve 26 of the coupling section 20 in such a way that the damping projections 64, with a contact surface 66, each come into contact with the contact surfaces 36 of the wing-shaped connecting projections 34. In a further step, the central bearing shaft 52 can be inserted into the receptacle 38a from the other side, and the tooth-shaped connecting projections 54 are aligned in such a way that they can be received in the remaining spaces between the damping projections of the damping element 62 and the connecting projections 34 of the coupling section 20. If these three components are aligned with each other, as in Fig.As shown in Figure 3A, axial fixation can be achieved with clamping rings 72 and 74, which are received in corresponding annular grooves 26b and 58.

[0042] Finally, the coupling mechanism 22 is mounted, i.e., the spring element 32 with the actuating sleeve 24 is pushed onto the coupling sleeve 26, and the actuating sleeve 24 is axially fixed by means of a clamping ring 76 (received in an annular groove 38c). The spring element 32 serves to preload the actuating sleeve in its locking position.

[0043] The dampened quick-change attachment provides good protection of the screwdriver from unwanted braking torques during hard screwdriving and thus extends the service life of the machine tool.

Claims

[1] Quick-change attachment (10) for a machine tool (100), comprising a first coupling section (20) which can be coupled to the machine tool (100), a second receiving section (40) which can be coupled to a tool, and a damping section (60) arranged between the coupling section (20) and the receiving section (40), wherein the coupling section (20) comprises a coupling mechanism (22) which is designed for releasable coupling to a drivable drive spindle (102) of the machine tool (100) in such a way that a torque about a longitudinal axis (L 100) of the drive spindle (102) can be transferred from the drive spindle (102) to the coupling section (20), and wherein the receiving section (40) has at least one receiving geometry for releasably receiving the tool and at least one connecting geometry for transmitting torque from at least one corresponding counter-connecting geometry on the coupling section (20) to the connecting geometry of the receiving section (40), characterized byin that the damping section (60) comprises at least one damping element (62) which is arranged between the connection geometry and the counter-connection geometry for the damped torque transmission from the coupling section (20) to the receiving section (40) or from the receiving section (40) to the coupling section (20) in such a way that the transmission of the torque from the counter-connection geometry or the connection geometry via the damping element (62) to the respective other connection geometry or counter-connection geometry can take place in a form-fitting manner in the direction of the torque to be transmitted, wherein the connected components, the counter-connection geometry of the coupling section (20), the damping element (62) and the connection geometry of the receiving section (40), are supported on one another in the direction of the torque damped by the damping element (62) and thus in the circumferential direction, whereby the damping element (62) is not subjected to any shear stress. [2] Quick-change attachment (10) according to claim 1, characterized by that the at least one damping element (62) is arranged interchangeably between the connecting geometry and the counter-connecting geometry and is made in particular of an elastic material. [3] Quick-change attachment (10) according to claim 1 or 2, characterized by that the at least one damping element (62) is annular and comprises at least one damping projection (64) which extends in the axial direction between the connecting geometry and the counter-connecting geometry. [4] Quick-change attachment (10) according to one of the preceding claims, characterized bythat the receiving geometry of the receiving section (40) for releasably receiving the tool comprises at least one outer receiving geometry, in particular an external square (44), onto which the tool can be plugged in sections, and at least one inner receiving geometry, in particular a hexagon socket (46), into which the tool can be plugged in sections, at a free end of the receiving section (40). [5] Quick-change attachment (10) according to one of the preceding claims, characterized bythat the connecting geometry and the counter-connecting geometry each have at least one connecting projection (54, 34), wherein the connecting projections (54, 34) are arranged relative to one another in such a way that the torque can be transmitted in the radial direction from the connecting projection (34) of the counter-connecting geometry via the damping section (60), in particular the damping projection (64) of the damping element (62) according to one of claims 3 or 4, to the connecting projection (54) of the connecting geometry and / or vice versa. [6] Quick-change attachment (10) according to claim 5, characterized bythat the connecting projections (34, 54) are tooth-shaped or wing-shaped and that the space between the at least one connecting projection (54) of the connecting geometry and the at least one connecting projection (34) of the counter-connecting geometry is filled by the damping element (62) in order to enable a damped transmission of the torque with almost no play. [7] Quick-change attachment (10) according to one of the preceding claims, characterized bythat the coupling mechanism (22) for releasably coupling to the driven drive spindle (102) of the machine tool (100) has a coupling sleeve (26) with at least one coupling recess (30) and an actuating sleeve (24) which at least partially surrounds the coupling sleeve (26) and which can be rotated in the circumferential direction relative to the coupling sleeve (26), as well as at least one coupling element (28) which is received in a space between the actuating sleeve (24) and the coupling sleeve (26) and which, as a result of a relative rotational movement of the actuating sleeve (24), can perform a radial relative movement to the coupling sleeve (26) in order to bring the at least one coupling element (28) through the at least one coupling recess (30) into positive engagement with an engagement structure of the drive spindle (102) of the machine tool (100) to be coupled. [8] Quick-change attachment (10) according to claim 7, characterized bythat the actuating sleeve (24) is prestressed by means of a spring element (32) in the direction of a relative position, in particular in the direction of a locking position, in which the coupling element (28) can be in positive engagement with the engagement structure of the drive spindle (102) of the machine tool (100) to be coupled through the at least one coupling recess (30). [9] Machine tool system (1000) comprising at least one quick-change attachment (10) according to one of claims 1 to 8 and a machine tool (100) with a drivable drive spindle (102), wherein the at least one quick-change attachment (10) can be coupled to the drive spindle (102) of the machine tool (100).

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