EP1763419B1 - Rapid locking device - Google Patents

Abstract

A rapid locking device axially secures a disc-type tool (16), in particular a grinding disc on the flange (24) of a driven spindle (14), the spindle (14) having an axial bore containing at least one locking element in the form of a plate spring (28), which co-operates with a locking pad (22). The tool can be locked between contact surfaces of the flange (24) and the locking pad (22), the distance between said surfaces being modifiable. The shank (30) of the locking pad (22) can be accommodated in the bore of the spindle (14) and can be secured in a friction fit by the locking element (20).

Description

The invention relates to a quick-release device for axially clamping a disc-shaped tool, in particular a grinding wheel on a flange of a driven spindle, such as from the document DE-43 36 620 known.

In the prior art, a plurality of quick-release devices for axially clamping a disk-shaped tool, in particular a grinding wheel are known.

In known quick-release devices for angle grinder, the spindle is held with a fork wrench or a built-Spindelarretierung after placing the grinding wheel and it is then placed a clamping nut by hand and tightened by means of a key. When the machine is switched on, the spindle starts up abruptly, so that due to the inertia, an automatic tightening of the grinding wheel takes place. During subsequent work, the clamping device continues to pull itself.

For tool change, the spindle is held and the clamping nut by means of a key, often solved with considerable effort.

There are still machines with a special spindle stop, which can be operated shortly before the spindle stops and blocks it abruptly, with the result that the grinding wheel continues to rotate due to its inertia and can thereby loosen the clamping nut. Will the Spindle stop triggered at high speeds, so the high-speed grinding wheel can screw down completely the clamping nut and the still rotating disc can then fall off the spindle and cause accidents and damage. To counteract this, special nuts are provided with a damping element, however, which are more expensive to manufacture than normal clamping nuts and less easily removed due to the increased friction when changing tools.

On the other hand, it is desirable to provide a brake device to bring the threaded spindle to a halt when the electric drive is switched off. This is to reduce the risk to the user to reduce the risk of contact with the still running grinding wheel in the wake when stopping the engine. In particular, it has traditionally been necessary to hold the angle grinder in the hands until the grinding wheel has come to a complete stop. If the angle grinder is already set down before the grinding wheel has been fully decelerated, it may cause injury to the ground or injury to persons. In order to prevent so-called angle grinders with a discharge brake from causing the grinding wheels to fall off, a large number of developments have been made. So revealed the DE 42 43 328 C1 a design in which the clamping element consists of a relative to the spindle rotatable clamping part and a threaded part on the threaded part which are rotatable against each other, and wherein between the two clamping parts or between the spindle and the screw on the threaded clamping part a relative movement between the two clamping parts at least partially reducing device is provided. As such means may be provided, for example, an O-ring.

In addition, the reveals DE 43 05 317 A1 a design in which a friction element is held in the clamping nut, and bears against the spindle under frictional engagement, for braking a relative movement between the spindle and the clamping nut.

Finally, the reveals DE 102 05 848 a design in which the nut is provided with a compressible pressure ring of the tool.

All of these designs have the disadvantage of being constructed to be relatively complicated, and on the other by the mother, which protrudes beyond the tool to have a relatively large height in the axial direction.

The invention therefore has the object to provide an alternative solution that allows clamping and retightening a tool, while preventing accidental release of the tool from the threaded spindle z. B. when braking the spindle.

The invention solves this problem by a quick-release device according to claim 1.

By inventively provided here design, can be waived in favor of a frictional engagement by means of a nut or a clamping screw, which engages in an internal thread of the spindle Layout. In this way, in particular by the purely axial support unintentional release is avoided.

In addition, it can be provided that the head of the clamping fungus can only slightly protrude beyond the tool. Unlike a mother, in which the holder and thus the traction in the region of the mother and thus takes place axially outside of the tool, the determination takes place in the region of the bolt of the clamping fungus and thus in the spindle, which does not protrude beyond the tool.

Furthermore, it is provided that the clamping mushroom is held under frictional engagement in the clamping element, which may be in particular in the clamping element to disc springs. The disc springs may be provided here as a slotted disc spring package, which are arranged inclined in the radial direction, wherein preferably the outer periphery of the plate spring packet in the direction of the tool, and the inner periphery of the plate spring assembly in the direction of an electric hand tool in which the quick-release device is provided. When inserting the tensioning mushroom in the disc spring assembly is then a first clamping of the clamping fungus, since only a small clearance between the cone and plate spring assembly is provided. Due to the inclination of the disc springs can be achieved here that an insertion of the tensioning mushroom is possible because of the preferably small, preset game withdrawal in the opposite direction, the clamping direction of the disc springs, however, avoided by further application of the springs on the bolt of the clamping mushroom. Conceivable, however, are other clamping elements, such as friction linings, etc.

For the first clamping can already be applied after a first design bias before inserting the clamping mushroom. Alternatively or additionally, after inserting the tensioning mushroom, it may further proceed that a first or further tension by means of a clamping device which may correspond to the biasing means which acts on aids on the disc spring assembly, and this loaded so that the inner diameter of the disc spring assembly is reduced, is applied.

In this case, the clamping device may be designed so that in particular an adjusting element, such as a lever may be provided, wherein the lever is equipped with a toothed segment, and the lever cooperates with its toothed segment with a toothing, another element, directly or indirectly causes a tension of the clamping element. It can be provided that, for example, the lever can be applied in a first position, in particular to the quick-release device, in which the sector gear is disengaged. The lever can then be brought to a second position, for example by being pivoted about a pivot point in which the teeth of the lever engage with the teeth of the further element. It can then be further provided that the lever in a further movement about its pivot axis performs an adjusting movement, whereby a clamping of the clamping element is achieved. The provision of the lever can then be done manually or automatically in the first position. The release of the voltage takes place in the reverse manner.

In principle, however, other clamping devices are conceivable.

Further tensioning of the disk spring assembly and tensioning of the disk spring assembly relative to the tensioning mushroom can alternatively or additionally take place at startup of an electric hand tool on which the quick release device is arranged, as by a relative movement during startup of the spindle between the flange and the tool it to a relative movement and thus to a tensioning or

Tensioning comes, whereby the disc springs are further loaded in the direction of their "block position".

In order to facilitate the tensioning by the relative movement, it may be provided that a friction element or a spring element is provided between the flange and the tool in order to achieve a secure contact between flange and tool when loosening or retightening. By this additional element, which can be formed in particular by a friction element or a plate spring, a force and torque transmission between the flange and disc is to be ensured.

In particular, it may be advantageous to design the frictional forces between the flange and the tool so that a slight return is possible.

Due to the fact that no spindle protruding from the tool is provided, the device according to the invention has the advantage that, even with different slice thicknesses, the spindle does not protrude out of the tool. In particular, in the case of grinding wheels with a low overall height, there is the disadvantage in the prior art that the spindle then protrudes axially clearly beyond the tool and that injuries to the workpiece during machining by the tool spindle can occur.

In addition, the design according to the invention has the advantage that commercially available grinding wheels and other disc-shaped processing means can be used and not - as provided in the prior art, special grinding wheels must be used, if a braking device is provided.

In addition, the system according to the invention has the advantage of a quick change of the tool allow, without the spindle must be locked, since no rotational movement for changing the tool and for new clamping or loosening is necessary.

In particular for releasing the tool, it is advantageous if the clamping mushroom is decoupled from the tool with respect to the torque transmission. For this purpose, according to one embodiment, a tongue and groove arrangement can be provided, whereby the clamping mushroom is directly coupled to the spindle. This additionally ensures that frictional forces in the circumferential direction must not be absorbed by the clamping element.

Generally, when the tool is decelerated, the post-tensioning effect is reversed, i. the tool continues to rotate with respect to the flange, thus causing a release of the tension of the tensioning element, in particular of the disk springs, which are increasingly inclined again. In addition, it is provided that the springs transmit only axial and no radial forces, so that the clamping fungus can then be easily lifted out of the opening, as soon as the clamping torque is released. The use of tools for changing is therefore usually not necessary.

Figur 1

einen Teil eines Gehäuses eines Winkelschleifers, mit einer erfindungsgemäßen Schnellspanneinrichtung;

Figur 2

eine Detailansicht aus Figur 1.

Furthermore, the invention comprises an electric hand tool, in particular an angle grinder with a quick-release device according to the preceding claims. The invention will be explained in more detail below with reference to a drawing. Show

FIG. 1

a part of a housing of an angle grinder, with a quick-release device according to the invention;

FIG. 2

a detailed view FIG. 1 ,

FIG. 1 shows a housing 10 for receiving a drive shaft in an opening 12 of the housing 10, which communicates with a spindle 14 for driving a tool 16, which is here formed by a grinding wheel. In this case, a transmission (not shown) is arranged in the housing 10. The grinding wheel is in this case clamped by means of a quick-release device, which is provided in its entirety by the reference numeral 18. The quick-clamping device 18 in this case comprises an electromachine-side part 20, and a clamping mushroom 22 which cooperates with the part 20.

FIG. 2 shows a section without tools FIG. 1 with the quick-clamping device 18. The quick-clamping device 18 in this case comprises a flange 24, against which the. Grinding wheel 16 abuts. For mounting the grinding wheel 16 with a device according to the invention, the grinding wheel 16 is placed on the flange 24, and the clamping mushroom 22 in an opening provided a cylinder 26, which cooperates with the spindle 14 and is part of the spindle 14, introduced. The cylinder 26 has in its interior disc springs 28 which are formed as slotted disc springs and whose outer diameter is closer to the grinding wheel 16 than its inner diameter. In this case, only a small gap between the bolt 30 of the clamping mushroom 22 and the inner diameter of the cup spring assembly 28 is provided.

In order to ensure a bias of the cup spring package for a secure axial frictional engagement between the disc spring assembly 28 and the bolt 30, a biasing device 32 may be provided which causes a cog 34 and a ramp arrangement buckling of the plate springs 28 in the form that they are with respect narrow their inner diameter. The adjustment takes place via a pivoting of the lever 33 which is connected to a toothed segment, which is engageable via a first pivoting movement with the gear 34 in engagement and triggers a further pivoting a clamping. The lever 33 is shown here in its applied basic position in which it is disengaged. If a corresponding electric hand tool now starts, the grinding wheel 16 initially remains due to the inertia of the mass, whereupon, as a result of a rotation of the flange 24 and a relative movement resulting therefrom, the cup spring pact is loaded and a tensioning of the clamping mushroom 22 is achieved.

After completion of the grinding operation then a deceleration of the spindle 14 via a braking device, not shown, whereupon the post-tension triggers by a turn made relative movement between the flange 24 and the grinding wheel 16, since the grinding wheel 16 continues to run due to their inertia for a certain time. However, the clamping forces are still sufficient to prevent release of the clamping mushroom 22. However, the clamping mushroom 22 can then be pulled out of the holder in the axial direction without further aids, in particular since the clamping mushroom 22 does not undergo any torque transmission from the grinding wheel 16 due to its design. For this purpose, the tensioning mushroom 22 has webs or springs 31 in the region of its bolt 30, which engage in grooves 29 of the spindle 14, so that here a direct torque transmission and decoupling is provided by the tool.

In this way, the three main criteria for quick change systems, namely the holder, the continuous adjustment and retightening can be ensured.

In particular, since no spindle 14 in the axial direction in Scope of the tool 16 is provided, grinding wheels of all thicknesses can be easily used without a part of the spindle 14 protrudes from the grinding wheel 16 in the axial direction. In particular, for so-called. Schrubbarbeiten this can be achieved a favorable disc utilization. In addition, this always has the advantage that injuries to the workpiece can be avoided by an outstanding spindle.

The quick-change system 18 according to the invention therefore offers, in addition to the advantages of a simple tool change, the advantages of securely holding the grinding wheel even when the spindle is being decelerated, whereby conventional grinding wheels can be used at the same time.

Claims (8)

1. Quick-clamping device for axially clamping a disc-shaped tool (10), in particular a grinding wheel, on a flange (24) of a driven shaft (14), the shaft (14) having an axially extending bore, in which at least one clamping element (28) is arranged, which cooperates with a dome-headed stud (22), it being possible to clamp the tool between contact surfaces of the flange (24) and of the dome-headed stud (22), the distance between which surfaces can be varied, a bolt (30) of the dome-headed stud (22) being able to be received in the bore of the shaft (14), characterised in that the bolt can be clamped in a frictionally engaged manner with the clamping element (20).
2. Quick-clamping device for axially clamping a disc-shaped tool (10), in particular a grinding wheel, on a flange (24) of a driven shaft (14), the shaft (14) having an axially extending bore, in which there is arranged at least one clamping element (28), which cooperates with a dome-headed stud (22), it being possible to clamp the tool between contact surfaces of the flange (24) and of the dome-headed stud (22), the distance between which surfaces can be varied, a bolt (30) of the dome-headed stud (22) being able to be received in the bore in the shaft (14), characterised in that the bolt can be clamped in a frictionally engaged manner with the clamping element, a slotted disc spring assembly which is inclined in the radial direction being provided as a clamping element (20).
3. Quick-clamping device according to claim 1, characterised in that disc springs (28) are provided as a clamping element (20).
4. Quick-clamping device according to any one of claims 1 to 3, characterised in that the clamping element (20) can be pre-tensioned.
5. Quick-clamping device according to any one of the preceding claims, characterised in that the dome-headed stud (22) is uncoupled from the tool (16) in terms of the moment transfer.
6. Quick-clamping device according to any one of the preceding claims, characterised in that the tool (16) can be re-tensioned, or released after re-tensioning, by means of a relative movement between the tool (16) and the flange (24).
7. Quick-clamping device according to any one of the preceding claims, characterised in that the clamping element (28) acts in the axial direction.
8. Power tool, in particular an angle-grinder, comprising a quick-clamping device (18) according to any one of the preceding claims.

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