EP2017036B1 - Power tool - Google Patents

Description

The invention relates to a power-driven hand tool with a motor-driven drive spindle for driving a tool, wherein the tool is fixable to a holding portion of the drive spindle by means of a fastener, with a displacement device for displacement of the fastener between a release position in which the fastener is detachable from the drive spindle , and a clamping position, in which the fastening element is clamped against the holding portion by a spring element, wherein the fastening element has an insertable into the drive spindle clamping shaft which is fixed axially in the clamping position in the drive spindle for clamping the tool, and in the release position detachable is.

Such a power-driven hand tool is from the WO 2005/102605 A1 known.

In the known hand tool a fastener is insertable through a mounting opening of the tool in the drive spindle and clamped therein to clamp the tool against the holding portion of the drive spindle and set positively.

For many applications, such a jig for clamping a tool is sufficient. However, it has been found that the forces which can be generated with the known tensioning device are generally insufficient at high tensioning forces in order to withstand very high loads, as can occur in particular with oscillation-driven sawing tools and cutting tools.

From the EP 0 319 813 A2 is a hand tool, in particular an angle grinder, known which has a similar tool clamping device.

Here, a clamping element in the form of a screw 40 is provided, which is screwed into a thread of a tool spindle arranged in a tie rod 48. The clamping element can be acted upon by means of a spring 50 via the tie rod 48, after which it presses a clamping flange 34 axially against a grinding wheel 32 and thus determines the grinding wheel 32 on a mating flange 30 of the tool spindle. Here, it is provided that the clamping flange 34 positively, so against rotation to store in the tool spindle.

Such a clamping device can be effective in an angle grinder with exclusively rotating grinding wheels loosening the grinding wheels However, the grinding wheel can rotate in the event of overload or abrupt shock or jolt loads. The known clamping device can not be transferred to hand tools with oscillating driven tools.

Other clamping devices for clamping tools on power tools without the aid of an auxiliary tool are from the DE 41 22 320 A1 and from the EP 0 152 564 B1 known. Here, a hollow drive shaft is provided, a slidably mounted therein spindle having a displacement device and a clamping point, which is formed from a central fastening element or a flange which is clamped by means of the displacement device against the drive shaft. Here, between the fastening element and the drive shaft, a positive connection may be provided to prevent loosening of the tool during braking operations.

However, the clamping devices in question are designed exclusively for rotationally driven power tools. A transmission to oscillating powered power tools is not possible.

Against this background, the invention has the object, a power tool of the type mentioned, the drive spindle to his

Longitudinal axis oscillating drivable to specify, in which a safe voltage of the tool on the drive spindle is ensured without the aid of auxiliary tools and can be easily solved for tool change. Here, the clamping device should be suitable for receiving the highest possible loads, as they occur in oscillating driven tools.

This object is achieved in a power tool according to the initially mentioned type in that a collet for clamping the tool is provided against the holding portion, which is stretched in the clamping position by the fastener against the holding portion and that the collet on its outer surface for positive reception of the tool is formed at its attachment opening, preferably formed polygonal, wherein the fastener engages the collet such that in the cocking position a positive locking element of the collet is acted upon by the fastener against a positive locking counterpart of the drive spindle, and wherein the fastener has a portion with an inclined Has surface whose extension engages with appropriately adjusted inner surface of the collet.

The object of the invention is completely solved in this way.

According to the invention a significantly increased clamping force over conventional clamping systems is achieved by the use of a collet for clamping the tool against the holding portion and by positive coupling of the collet with the tool. Furthermore, a secure torque transmission is ensured even with highly loaded, oscillating driven machines by the positive connection of the collet with the tool.

In addition, there is the advantage that the positive connection between the collet and drive spindle, which is always provided for reasons of handling with a certain play, is further intensified, so that a completely backlash-free positive connection is ensured in the clamping position. In this way, particularly high torques can be transmitted without adverse effects, such as a heating of the tool by slippage or widening of the tool occurs at its attachment opening.

Furthermore, the engaging in the collet portion of the fastener may be formed approximately conical.

By this measure, there is a further intensification of the positive connection between collet and drive spindle, so that in the clamping position a perfect fit is guaranteed.

According to a further embodiment of the invention, a spring element is provided between the collet and the fastening element.

By this measure, a release of the fastener is facilitated by the collet after the transfer of the displacement device in the release position.

According to a further embodiment of the invention, the collet is positively connected to the holding portion.

By this measure, the transmission of high torques at heavily loaded oscillatingly driven tools is improved on the tool.

According to a further embodiment of the invention, the collet is held on the clamping shank of the fastening element and with the fastening element connected to a detachable in the release position of the drive shaft unit.

Since the fastener and the collet are so connected to a common unit, there is a simplified handling when removing and placing on the drive shaft.

According to a further embodiment of the invention form-locking elements are provided on the fastening element, which cooperate with movable clamping pieces for the positive fixing of the fastening element in the clamping position.

The use of positive locking elements ensures even greater safety against the release of stress under heavy loads.

According to a further embodiment of the invention radially movable clamping pieces are provided.

In this way, a high clamping force can be achieved.

According to a development of this embodiment, a sleeve is received in the drive spindle, on which the clamping pieces are held radially displaceable.

By these measures, a reliable and robust implementation of a spring element axially applied clamping force in a radial holding force for fixing the clamping shaft on the drive spindle is made possible by simple means.

Here, the clamping pieces are preferably biased by the spring element in the radial direction towards the center against the positive locking elements.

This also supports the fixation of the clamping shaft on the drive shaft.

According to a further embodiment of the invention, the clamping pieces are held in recesses of the sleeve.

In this way, a simple assembly and safe movement of the clamping pieces between clamping position and release position allows.

In a further preferred embodiment of the invention, the clamping pieces on their side facing the tool on inclined surfaces which cooperate with inclined surfaces on the sleeve such that a movement of the sleeve against the inclined surfaces of the clamping pieces causes an application of the clamping pieces towards the center.

In this way, an advantageous implementation of a bias generated in the axial direction by spring force results in a holding force for fixing the fastening element in the axial direction.

According to a further embodiment of the invention, the sleeve is biased by the spring element in the axial direction in the direction of the closed position.

According to a further embodiment of the invention, an ejector in the form of an axially fixed to the drive spindle sleeve is provided on the drive spindle, which limits a movement of the clamping pieces in the axial direction of the tool.

By this measure, a secure opening of the clamping pieces is ensured when the fastener to change the tool to be pulled together with the collet from the drive spindle in the release position.

At the same time a high clamping force can be transmitted to the collet by the spring element. The spring element should preferably be dimensioned such that the highest possible clamping force results, which is sufficient for all applications. For this purpose, the spring element may be formed, for example, as a plate spring package. However, other spring shapes are conceivable.

It is understood that the features of the invention mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the invention.

Figur 1

ein erfindungsgemäßes Handwerkzeug mit einem Oszillationsantrieb im Bereich des Getriebekopfes in vereinfachter, geschnittener Darstel- lung in einer Spannstellung.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings. It shows:

FIG. 1

an inventive hand tool with an oscillating drive in the region of the gear head in a simplified, cut representation in a clamping position.

In FIG. 1 is an inventive power-driven hand tool shown cut in the region of its gear head and designated overall by the numeral 10. The hand tool 10 has a drive shaft 12, at the outer end of a tool 62 is attached by means of a clamping device explained in more detail below.

The drive spindle 12 is driven in a manner not shown oscillating by a driven by an eccentric tuning fork 24. As indicated by the double arrow 15, the drive spindle 12 is thereby moved about its longitudinal axis 13, with a high frequency between about 10,000 and 25,000 oscillations per minute and a small pivot angle between about 0.5 and 7 °.

Such oscillating powered hand tools 10 have recently been used for a variety of tasks to perform numerous specialized tasks, including, but not limited to. The removal of motor vehicle discs by means of an oscillating driven knife, the saws with oscillating driven saw blades, a grinding and much more.

In contrast to rotating drive spindles occur in oscillating driven drive spindles large impulsive torques in both directions with high dynamics. As a result, very high clamping forces (in a relatively small space) and a robust, backlash-free mechanism are necessary to ensure the maintenance of the tools on the drive spindle under all operating conditions.

These requirements are met in the inventive hand tool 10 with a special clamping system, at the same time a quick clamping and releasing a tool 62 is made possible without the aid of an auxiliary tool.

The drive shaft 12 is formed in two parts in this embodiment and has a spindle tube 18 which is bolted to a bearing pin 20 via a thread 22. The drive spindle 12 is mounted at its upper end in the region of the bearing journal 20 by means of a bearing 14 and at its lower end in the region of the spindle tube 18 by means of a bearing 16.

For fixing the tool 62 at the outer end of the spindle tube 18, a collet designated generally with 66 is provided, which engages positively in a mounting opening 64 of the tool 62. The collet 66 is also positively connected to the spindle tube 18 and in the in FIG. 1 shown clamping position by a fastener 48 against the drive spindle 12 clamped so that the tool 62 is clamped by the collet 66 against a holding portion 19 at the outer end of the spindle tube 18.

The fastening element 48 has a clamping shank 49, which in the clamping position shown here in a sleeve 38 with clamping pieces 40 of a generally designated by the numeral 36 closure is positively fixed within the spindle tube 18.

In this case, the clamping force is applied by a spring element in the form of plate spring package 58, which is held within the spindle tube 18 between a locking washer 59 which engages in an annular groove 60 and the closure 36. Due to the tension of the disk spring assembly 58, the tool 62 between the holding portion 19 of the spindle tube 18 and the collet 66 is firmly clamped.

For the purpose of a quick tool change without the aid of an auxiliary tool, the shutter 36 between an in FIG. 1 illustrated clamping position and a release position by means of a displacement device 25 axially displaceable. For this purpose, the closure 36 is held between the pressure piece 26 and the plate spring package 58 by the Federkraftbeaufschlagung. The pressure piece 26 is in the clamping position positively in a correspondingly shaped recess of the journal 20 and protrudes with its cylindrical shaft through a central bore of the journal 20 down.

The displacement device 25 has an eccentric 30, which by means of a in FIG. 1 only with 28 indicated clamping lever about an eccentric axis 31 is pivotable.

In the clamping position according to FIG. 1 there is a distance between the outer end face 34 of the pressure piece 26 and the opposing pressure surface 32 of the eccentric 30. In the clamping position thus the pressure piece 26 and thus the entire drive spindle 12 is decoupled from the displacement device 25 so that during operation no frictional forces on the drive spindle 12 can be transmitted.

If, however, the clamping lever 28 from the in FIG. 1 shown clamping position pivoted forward in the direction of arrow 33 in a release position, the pressure surface 32 of the eccentric 30 comes into contact with the end face 34 of the pressure piece and moves the pressure member 26 against the action of the plate spring assembly 58 in the direction of the tool 62, whereby the Closure 36 is pushed outwardly to release the fastener 48, as will be described in more detail below.

The sleeve 38 of the closure 36 is annular and slidably received within the inner surface of the spindle tube 18. The tool-side end face of the sleeve 38 serves to bear the cup spring assembly 58. The inner surface of the sleeve 38 is formed as an inclined, cone-shaped inclined surface 46.

The sleeve 38 cooperates with three clamping pieces 40, which are held in correspondingly shaped recesses of the sleeve 38. The clamping pieces 40 have on their side facing the tool 62 each have an inclined surface and can move due to the same inclination as the inclined surface 46 along the sleeve 38 axially and at the same time radially. At their side facing towards the center, the clamping pieces 40 are each provided with a toothing 44 which cooperates with a correspondingly shaped toothed section 50 on the clamping shank 49 of the fastening element 48.

The clamping pieces 40 have on their side facing the pressure piece 26 each have an axial bore 41, within which a spring 42 is received, which may be formed as a helical spring and which serves a pressure of the clamping pieces 40 in the direction of the tool 62.

The sleeve 38 is bolted to the pressure piece 26 via screws, not shown. The screws are screwed through correspondingly shaped holes of the pressure piece 26 into associated threaded holes in the sleeve 38.

This two-part construction serves to mount the clamping pieces 40 in associated recesses of the sleeve 38.

The structure of the closure 36 and the associated displacement device 25 is basically known and corresponds to that in the WO 2005/102605 known structure, which is fully incorporated herein by reference.

In deviation from the WO 2005/102605 However, the spring element 58 is not designed as a helical spring, but as a plate spring assembly 58 and is supported on the tool side on the locking ring 59, while it abuts on the sleeve 38 on the opposite side. An ejector 56 in the form of a sleeve is enclosed by the plate spring package 50 and is located at its tool-side end with a flange portion 57 on the locking ring 59 at.

In contrast to the above-mentioned, known embodiment, the fastener 48 engages with a head portion 51 but not directly on the tool 62, but engages with a cone-shaped portion 53 in a correspondingly shaped recess 78 of the collet 66, so that the collet 66 through the Fastener 48 is clamped with a flange 76 directly against the tool 62 and thus against the holding portion 19.

The spindle tube 18 is provided in its outer region on its inner surface with a polygonal section 74 in the form of a twelve-edged. The collet 66 has a hexagonal-shaped polygonal section 72, which adjoins the flange section 76 and engages positively in the polygonal section 74 of the spindle tube 18.

In the in FIG. 1 shown clamping position is thus the collet 66 with its polygonal section 72 positively held in the polygonal section 74 of the spindle tube 18.

Since now the conical portion 53 of the fastener 48 engages under the action of the strong disc spring assembly 58 in the correspondingly shaped recess 78 of the collet 66, the collet 66 in the region of the polygonal section 72 tends to be slightly widened outward and is so in the polygonal section 74 of the spindle tube 18th pressed so that any game that is necessary for inserting the collet 66 in the spindle tube 18 is completely eliminated.

In this way, an extremely firm, positive connection between the collet 66 and spindle tube 18 is achieved.

The tool 62 is held with its fastening opening 64, which is formed hexagonal, at the same time form-fitting manner on the polygonal section 72 of the collet 66.

Overall, this results in a very good, play-free positive connection between the collet 66, tool 62 and spindle tube 18th

Thus, a very high clamping force, which is achieved by the plate spring assembly 58, play on the tool 62 play, so that high torsional moments changing direction of rotation, which arise through the Oszillationsantrieb, can be transmitted without problems.

The collet 66 has a central cylindrical bore 67, with which it is held axially displaceable on the clamping shaft 49 with a released closure 36 by a certain amount.

The fastening element 48 and the collet 66 are connected, for example by an O-ring 68, which can be inserted by a certain amount in a recess 70 on the inner surface of the collet 66, captive to a common unit.

To change the tool 62, the clamping lever 28 is moved in the direction of the arrow 33. Thus, the closure 36 is transferred by the pressure piece 26 in the release position, in which the pressure piece 26 in a opposite FIG. 1 is in the direction of the tool 62 shifted position. As a result, the pressure piece 26 presses against the clamping pieces 40, so that they dodge 48 of the teeth 50 of the fastening element 48 radially outward, whereby the fastening element 48 is released and can be pulled together with the collet 66 from the spindle tube 18 ,

After replacing the tool 62, the common unit of fastener 48 and collet 66 can be reintroduced into the spindle tube 18 and then transferred again by moving the clamping lever 28 in the clamping position.

Between the two opposing radial surfaces at the end of the recess 78 of the collet 66 and the conical portion 53 of the fastener, a spring element 54 is further included in the form of a wave ring. This spring element 54 facilitates release of the fastening element 48 after a previously performed clamping operation, so that the fastening element 48 can be easily pulled out in the release position.

Claims (13)

1. A power-driven hand tool comprising a drive spindle (12) for driving a tool (62), that can be driven to oscillatingly about its longitudinal axis (13), which tool (62) can be fixed on a retaining section (19) of the dive spindle (12) by a securing element (48), further comprising a displacing device (25) that serves to displace the securing element (48) between a releasing position in which the securing element (48) can be released from the drive spindle (12) and a clamping position in which the securing element (48) is clamped on the retaining section (19) by a spring element (58), the securing element (48) comprising a clamping shaft (49) adapted to be inserted into the securing element (48), which is axially fixed in the drive spindle (12) for clamping the tool (62) in the clamping position, and which can be detached in the releasing position, characterized in that for clamping the tool (62) on the retaining section (19) a split chuck (66) is provided which is clamped on the retaining section (18) by the securing element (48) in the clamped position, and that the outer surface of the split chuck (66) has a design, preferably of polygonal shape, adapted to support the tool (62) in the area of its mounting opening (64) in form-locking engagement, wherein the securing element engages the split chuck (66) in such a way that in the clamping position a form-locking element of the split chuck (66) is urged by the securing element against a form-locking counter-element of the drive spindle, and wherein the securing element (48) comprises a section (53) with an inclined surface (52) which engages a recess (78) with a correspondingly adapted inner surface (78) in the split chuck (66).
2. The hand tool of claim 1, characterized in that the section of the securing element (48) that engages the split chuck (66) has a conical shape.
3. The hand tool of any of the preceding claims, characterized in that a spring element (54) is provided between the split chuck (66) and the securing element (48).
4. The hand tool of any of the preceding claims, characterized in that the split chuck (66) can be connected with the retaining section (19) in form-locking engagement.
5. The hand tool of any of the preceding claims, characterized in that in the clamping position the split chuck (66) is retained on the clamping shaft (49) of the securing element (48) and is connected with the securing element (48) to a single unit, for common removal from the drive shaft (12) in the releasing position.
6. The hand tool of any of the preceding claims, characterized in that form-locking elements (50) are provided on the securing element (48) that coact with movable clamping pieces (40) for fixing the securing element (48) in form-locking engagement in the clamping position.
7. The hand tool of claim 6, characterized in that the clamping pieces (40) are radially movable.
8. The hand tool of claim 6 or 7, characterized in that a sleeve (38) is received in the drive spindle (12) on which the clamping pieces (40) are retained for radial displacement.
9. The hand tool of claim 6, 7 or 8, characterized in that the clamping pieces (40) are biased by the spring element (58) toward the form-locking elements (50) in a radial direction toward the center.
10. The hand tool of any of claims 6 to 9, characterized in that the clamping pieces (40) are retained in recesses of the sleeve (38).
11. The hand tool of any of claims 6 to 10, characterized in that the sides of the clamping pieces (40) that face the tool (62) are provided with inclined surfaces (46) that coact with inclined surfaces on the sleeves (38) in such a way that any movement of the sleeve (38) relative to the inclined surfaces (46) of the clamping pieces (40) will urge the clamping pieces (40) toward the center.
12. The hand tool of any of claims 6 to 11, characterized in that the sleeve (38) is axially biased by the spring element (48) toward the closed position.
13. The hand tool of any of claims 6 to 12, characterized in that an ejector (56) in the form of a sleeve (38), fixed on the drive spindle (12) in axial direction, is provided on the drive spindle (12) for limiting any axial movement of the clamping pieces (40) on the side of the tool.

Images