EP3202533A1 - Clamping device - Google Patents

Abstract

Clamping device for the axial clamping of a disc-shaped tool, preferably a cutting disc, to a flange of a drivable spindle of a hand tool, with a friction in the clamped state voltage applied to the tool clamping disk, a central screw in a threaded receiving opening, which in an end face the spindle is formed, is screwed, with a control element which is rotatably connected to the screw, so that a force introduced into the control element hand force is transmitted as a tightening torque on the screw, and a first securing element which is formed with a corresponding, on the Flange provided second securing element cooperate such that when the screw is at least partially inserted into the receiving opening, the clamping disc is rotationally secured to the flange, wherein the clamping disc rotatable relative to the screw and the operating element r is. The first securing element of the clamping device is rotatable relative to the screw and rotatably mounted to the clamping disk.

Description

The present invention relates to a clamping device for axially clamping a disc-shaped tool, preferably a cutting disc, to a flange of a driven spindle of an electric hand tool. The hand tool may, for example, be a cut-off machine.

An applied to the spindle drive torque can be transferred exclusively frictionally engaged in the conventional design of the disc-shaped tools on the disc-shaped tools, as they have only a simple, central bore as an interface and thus provide no attack surfaces for a positive connection.

The attachment is accomplished by axially clamping one or more disk-shaped tools against a back flange on the spindle. The task of the clamping element is thus the application of a sufficient axial clamping force, so that the force and torque can be transmitted from the electric power tool to the disc-shaped tool. A sufficient clamping is characterized by the fact that the disc-shaped tools do not slip on the drive spindle.

From the prior art, various clamping devices of the type mentioned are known. These are, for example, clamping devices that require the use of an additional tool. Conventionally, disk-shaped tools are mounted on electric hand tool machines (e.g., angle grinders, parting cutters) with nuts on the drive spindle and tightened with a separate wrench (e.g., two-hole or open-end wrench). The big disadvantage of such fixtures is the separate key, which must be carried in addition to the actual system and can be lost.

Also known from the prior art are self-tightening clamping devices with release aids. So are from the German patents DE 38 24 040 C1 and DE 10 311 491 B4 For example, known clamping nuts, which are initially fixed hand-tight and rely on the self-tensioning effect by the reverse thrust during startup of the device. This effect is due to the inertia of the disc-shaped tools and the clamping nuts and the reaction forces of the disc-shaped tools during cutting in the underground. Between the disc-shaped tools, the clamping nut and the rear flange there is a frictional power transmission. The reaction forces cause the clamping nut increasingly clamped over the discs against the rear flange. For loosening a technical release aid is integrated in these clamping nuts, which make it possible to release the preload of the nut before it is unscrewed.

The disadvantage of such clamping devices is that the level of clamping force achieved is not limited by the automatic tightening up and thereby the clamping nut can be biased so strong that the release mechanism by hand can not be solved.

Another disadvantage is that even the resulting in the outlet of the power tool inertia reaction moments are transmitted to the clamping nut, which can lead to an automatic running of the clamping nut and the disc-shaped tools especially for hand tools with active discharge brake. From the running parts is a threat to the operator of the power tool.

Another possibility known from the prior art to make a separate key superfluous is to design the clamping device in such a way that a manual force is sufficient during assembly in order to achieve sufficient clamping of the disk-shaped tool on the handheld power tool. For either the hand strength can be increased and / or the friction losses can be minimized in order to achieve a higher clamping force from the same, limited manual force.

A known solution for improved utilization of the tightening torque in a high axial clamping force during clamping consists of a secondary thread in which balls rotate, which is effective in the last phase of the tightening process. Such a solution is for example from the European publication EP 0 846 526 A2 known.

Disadvantage of this tensioning device is that the dynamic reaction forces are not decoupled from the threaded portion and thereby the clamping device can tighten on the one hand excessively automatically and on the other can run off in an abrupt stopping of the spindle.

Another known from the prior art solution for improved conversion of a torque in a high axial clamping force during clamping is to choose a thread with a smaller diameter and small pitch and also minimize the Schraubenkopervibung a rolling bearing. Furthermore, dynamic reaction forces of interlocking elements between the discs facing the clamping disc and the Drive spindle intercepted, whereby an automatic clamping and automatic running is prevented. Such a clamping device of ITW Befestigungssysteme GmbH Spit is known from the market.

It is therefore an object of the present invention to provide a clamping device by which the disadvantages described above can be eliminated and in particular jamming between a securing element of the clamping device and a corresponding, provided on a spindle securing element can be avoided.

The object is solved by the subject matter of independent claim 1. Advantageous embodiments of the subject matter are contained in the dependent claims.

The object is achieved, in particular, by providing a clamping device for axially clamping a disk-shaped tool, preferably a cutting disk, on a flange of a drivable spindle of a handheld power tool, with a clamping disk frictionally engaged with the tool in the clamped state, a central screw which is in a threaded receiving opening formed in an end face of the spindle, can be screwed, with a control element which is rotatably connected to the screw, so that an initiated in the control hand force is transmitted as a tightening torque on the screw, and a first Secured element, which is designed to cooperate with a corresponding, provided on the flange second securing element such that when the screw is at least partially inserted into the receiving opening, the clamping disc to the flange positively secured against rotation is, wherein the tensioning disc is rotatable relative to the screw and the operating element.

According to the first securing element of the clamping device is rotatable relative to the screw and rotatably mounted to the clamping disk. In this way it can be ensured that a torque applied by the user and acting on the screw or unit of screw and operating element is converted in a particularly efficient manner into an axially acting clamping force for securing the disc-shaped tool to the drivable spindle of the hand tool.

The invention includes the recognition that by the fact that the clamping disc is freely rotatable relative to the screw or the driven unit of screw and control element, a relative position in the circumferential direction between the clamping plate and screw or between the clamping plate and control element is not clearly defined. Thus is also one Position between the first securing element and the corresponding second securing element when screwing the central screw in the formed on the end face of the spindle receiving opening with thread not defined.

According to an advantageous embodiment of the present invention can be provided that the first securing element is designed in the form of a sleeve with a polygonal inner profile and the second securing element includes a corresponding to the polygonal inner profile of the first securing element outer profile, so that the first securing element can be pushed onto the second securing element is. By pushing the first securing element onto the second securing element, a precise arrangement and thus a secure interaction of the two securing elements relative to one another can be achieved.
Furthermore, there is the advantage that the spindle of the power tool can be carried out particularly simply that it remains free of moving parts that favor synchronization.

In order to ensure a secure and particularly accurate fit arrangement of the clamping disk to the first and second securing element, according to a further advantageous embodiment of the present invention may be provided that the clamping disk includes a central recess and the first securing element includes a corresponding to the central recess outer profile, so that the first securing element can be inserted into the clamping disk.

According to a further advantageous embodiment of the present invention can be provided that the clamping disk and the first securing element is designed in one piece. In this way, an even better force or torque transmission can be ensured by the clamping disk on the first fuse element.

In addition, it can be provided in a further advantageous embodiment of the present invention that the screw is designed so that a thread of the screw is engageable only in the thread of the receiving opening, if in an assembled state of the clamping device, the first securing element at least partially with the second Fuse element interacts positively. This makes it possible to ensure that the user can only correctly turn the screw into the thread of the receiving opening when the first and second securing elements are arranged correctly relative to one another or the clamping device is correctly assembled. In other words, when the first and second securing element are positively connected with each other.

It has proved to be advantageous if the operating element is designed as a lid, which preferably surrounds the clamping disk at least in sections.

In a particularly advantageous embodiment of the present invention, the tensioning device has a bearing. Preferably, the bearing is an axial needle bearing. The bearing is arranged for the rotational decoupling of screw and clamping disk, but in particular preferably not exclusively when the clamping disk is rotationally secured to the flange in a form-fitting manner.

It has proved to be particularly advantageous if the operating element, the clamping disk and the first securing element are arranged coaxially with each other on the screw. Preferably, the operating element, the clamping disk and the first securing element are held by at least one locking ring in or at least partially in the operating element.

Further advantages will become apparent from the following description of the figures. In the figures, various embodiments of the present invention are shown. The figures, the description and the claims contain numerous features in combination. The skilled person will conveniently consider the features individually and summarize meaningful further combinations.

In the figures, identical and similar components are numbered with the same reference numerals.

Fig. 1

eine Seitenansicht einer erfindungsgemäßen Spannvorrichtung mit einem scheibenförmigen Werkzeugs in einem zusammengebauten Zustand der Spannvorrichtung;

Fig. 2

eine perspektivische Ansicht der Spannvorrichtung in einem auseinander gebauten Zustand der Spannvorrichtung ohne das scheibenförmige Werkzeug;

Fig. 3

eine perspektivische Ansicht der Spannvorrichtung in einem auseinander gebauten Zustand der Spannvorrichtung;

Fig. 4

eine seitliche Schnittansicht der Spannvorrichtung entlang der Schnittlinie A - A in Fig. 1;

Fig. 4a

eine Schnittansicht der Spannvorrichtung entlang der Schnittlinie B - B in Fig. 4;

Fig. 5

eine weitere seitliche Schnittansicht der Spannvorrichtung entlang der Schnittlinie A - A in Fig. 1;

Fig. 5a

eine Schnittansicht der Spannvorrichtung entlang der Schnittlinie B - B in Fig. 5;

Fig. 6

eine perspektivische Ansicht der Spindel;

Fig. 7

eine seitliche Schnittansicht der Spindel;

Fig. 8

eine perspektivische Ansicht des ersten Sicherungselements; und

Fig. 9

eine weitere perspektivische Ansicht des ersten Sicherungselements.

Show it:

Fig. 1

a side view of a clamping device according to the invention with a disc-shaped tool in an assembled state of the clamping device;

Fig. 2

a perspective view of the clamping device in a disassembled state of the clamping device without the disc-shaped tool;

Fig. 3

a perspective view of the clamping device in a disassembled state of the clamping device;

Fig. 4

a sectional side view of the clamping device along the section line A - A in Fig. 1 ;

Fig. 4a

a sectional view of the clamping device along the section line B - B in Fig. 4 ;

Fig. 5

a further sectional side view of the clamping device along the section line A - A in Fig. 1 ;

Fig. 5a

a sectional view of the clamping device along the section line B - B in Fig. 5 ;

Fig. 6

a perspective view of the spindle;

Fig. 7

a lateral sectional view of the spindle;

Fig. 8

a perspective view of the first securing element; and

Fig. 9

another perspective view of the first fuse element.

EXAMPLES

An inventive clamping device 1 is in Fig. 1 shown in an assembled state.

The tensioning device 1 essentially comprises a screw 2, an operating element 3, a first running disk 4, an axial needle bearing 5, a second running disk 6, a tensioning disk 7, a first securing element 8 and a counter-clamping disk 9 (cf. Fig. 1 . 2 . 3 ). The tensioning device 1 interacts with a spindle 10 of a hand-held power tool not shown in the figures. The spindle 10 further includes a second securing element 12, which is located on a flange 13 of the spindle 10 (see. Fig. 2, 3rd ).

The clamping device 1 is used for axially clamping a disc-shaped tool 14 on the flange 13 of the right side in Fig. 1 The driven spindle 10 is associated with a hand tool, not shown in the figures, which may be, for example, a cut-off machine. The disk-shaped tool 14 may be, for example, a plate-shaped grinding wheel.
However, it is also possible for the disk-shaped tool 14 to be a flat cutting disk. In the hand tool, not shown, it may be an angle grinder or the like. Alternatively, the clamping device according to the invention can also be realized in a non-handheld machine tool.

The clamping device 1 includes a clamping plate 7 which rests in an assembled or clamped state of the clamping device 1 frictionally on the tool 14, for example, a plate-shaped grinding wheel to clamp it to the spindle 10 of the hand tool, not shown.

When screw 2 is a central screw, which holds the entire clamping device 1 in the assembled state. The screw 2 includes a screw head 2a and a thread 2b, which can be screwed into a thread 15 which is formed in a receiving opening 16 on a free end face 17 of the spindle 10.

The operating element 3 is designed essentially in the form of a lid with a central recess 18. Due to the positive connection of control element 3 and screw 2, the control element 3 is rotatably connected to the screw 2, so that in the control element 3 by rotation of the control element 3 in radial direction R initiated manual force is transmitted as a tightening torque on the screw 2. About a corresponding profile device to the central recess 18 of the control element 3 and the screw head 2a of the screw 2, the positive connection between the screw 2 and the control element 3 is achieved. Alternatively, the screw 2 and the control element 3 may also be designed in one piece or materially connected (gluing, welding, soldering or the like) to one another.

The first securing element 8 of the clamping device 1 is in the Fig. 1 illustrated embodiment designed as a sleeve with a hexagonal inner profile 19 (see also Fig. 8 and 9 ). It is essentially like a nut with a hexagon socket. In addition, the first securing element 8 at one end 8a contains a polygonal outer profile 20. As in particular in FIG Fig. 8 shown, the polygonal outer profile 20 is substantially a square profile with chamfered corners.

The clamping disk 7 contains in the middle a substantially square recess 21. The shape of the recess 21 corresponds to the square outer profile 20 of the first securing element 8, so that the square outer profile 20 of the first securing element 8 can be inserted into the square recess 21 of the clamping disk 7 , As a result, the first securing element 8 and the clamping disk 7 are positively connected to one another.

Alternatively, the first securing element 8 and the tensioning disk 7 may also have other outer profile and recesses corresponding to each other. Furthermore, the first securing element 8 and the tensioning disk 7 can also be embodied in one piece or can be connected to one another in a material-locking manner.

On the flange 13 of the spindle 10 a to the first securing element 8 corresponding second securing element 12 is arranged. As in particular in the Fig. 2 . 3 . 6 illustrated, the second securing element 12 includes a hexagonal outer profile 22 corresponding to the hexagonal inner profile 19 of the first securing element 8. When hexagonal inner profile 19 of the first securing element 8 with the hexagonal outer profile 22 of the second securing element 12 are engaged, not only is the first securing element 8 to the second securing element 12 but also the clamping disk 7 to the flange 13 rotationally secured to each other.

As already mentioned above, in the illustrated embodiment, this is realized such that the outer profile 20 of the first securing element 8 protrude into the corresponding recess 21 of the clamping disk 7, the inner profile 19 of the first securing element 8 is pushed onto the outer profile 22 of the second securing element 12 and Screw 2 in the direction of N by the clamping disk 7, the first securing element 8, the disk-shaped tool 14 and in the threaded opening 15 equipped with the receiving opening 16 of the spindle 10 is screwed (see. Fig. 3 ). The clamping disk 7, the first securing element 8 and the second securing element 12 are thus positively connected to each other.

According to the invention, the first securing element 8 of the clamping device 1 is rotatable relative to the screw 2 and rotatably mounted to the clamping disk 7.

The clamping device 1 in the present case has a bearing 23 in the form of an axial needle bearing, which is supported between two running disks 24, 25. The designed as an axial needle bearing bearing 23 is the rotational decoupling of screw 2 and clamping plate 7 when the clamping plate 7 is rotationally secured to the flange 13 positively.

Like the same Fig. 1 can be removed, the screw 2, the control element 3, the two pulleys 24, 25, the first securing element 8 and the clamping disc 7 are arranged coaxially with each other.

In the assembled state (cf. Fig. 2 ), the operating element 3, the clamping disk 7, the first securing element 8, the two pulleys 24, 25 and the axial needle bearing 23 are arranged on the screw 2 and secured on this by a securing ring 26 in the form of a snap ring. An additional ring 27 serves to deflect the axially acting force in the assembled state of the tensioning device 1 so that a radial force component is produced on the securing ring 26.

Claims (8)

Clamping device (1) for axially clamping a disc-shaped tool (14), preferably a cutting disc, to a flange (13) of a drivable spindle (10) of a hand tool machine, with
a clamping disk (7), which bears on the tool (14) frictionally engaged in the clamped state,
a central screw (2) which can be screwed into a receiving opening (16) which is provided with a thread (15) and which is formed in an end face of the spindle (10), with a control element (3) which is non-rotatable with the screw (10). 2) is connectable, so that in the operating element (3) initiated manual force is transmitted as a tightening torque on the screw (2), and
a first securing element (8) which is designed to cooperate with a corresponding second securing element (12) provided on the flange (13) such that when the screw (2) is at least partially inserted into the receiving opening (16), the tensioning disc (7) to the flange (13) is positively secured against rotation, wherein the clamping disc (7) relative to the screw (2) and the operating element (3) is rotatable,
characterized in that the first securing element (8) of the clamping device (1) relative to the screw (2) rotatably and the clamping disc (7) is rotatably mounted. Clamping device (1) according to claim 1,
characterized in that the first securing element (8) in the form of a sleeve with a polygonal inner profile (19) is configured and the second securing element (12) to the polygonal inner profile (19) of the first securing element (8) corresponding outer profile (22) in that the first securing element (8) can be pushed onto the second securing element (12). Clamping device (1) according to claim 1 or 2,
characterized in that the clamping disc (7) includes a central recess (21) and the first securing element (8) to the central recess (21) corresponding outer profile (20), so that the first securing element (3) in the clamping disc (7 ) is insertable. Clamping device (1) according to claim 1 or 2,
characterized in that the clamping disc (7) and the first securing element (8) is designed in one piece. Clamping device (1) according to at least one of the preceding claims,
characterized in that the screw (2) is designed so that a thread (2a) of the screw (2) is engageable only in the thread (15) of the receiving opening (16) when in an assembled state of the clamping device (1) the first securing element (8) at least partially cooperates positively with the second securing element (12). Clamping device (1) according to at least one of the preceding claims,
characterized in that the operating element (1) is designed as a lid, which surrounds the clamping disc (7) at least in sections. Clamping device (1) according to at least one of the preceding claims,
characterized in that the clamping device (1) has a bearing (23), preferably an axial needle bearing for rotational decoupling of screw (2) and clamping disc (7) when the clamping disc (2) to the flange (13) is positively secured against rotation. Clamping device (1) according to at least one of the preceding claims,
characterized in that the operating element (3), the tensioning disk (7) and the first securing element (8) are arranged coaxially with each other on the screw (2) and by at least one retaining ring (26) in or at least partially in the operating element (3 ) being held.

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