EP1852218B1 - Oscillation drive - Google Patents

Abstract

The oscillating drive has a shaft whose free end (16) forms a flat mounting (18) for a tool (22). Lugs (36) on the mounting fit though slots on the tool and deform them so that the tool is prevented from rotating with respect to the mounting.

Description

• einer Abtriebswelle, die um ihre Längsachse drehoszillierend antreibbar ist und ein freies Ende aufweist,
• einer Aufnahme am freien Ende der Abtriebswelle, die eine Anlagefläche zur Anlage eines Werkzeugs aufweist,
• einem Befestigungsabschnitt an der Aufnahme, der gegenüber der Anlagefläche erhaben in Richtung der Längsachse nach außen hervorsteht und der zur formschlüssigen Verbindung mit einer Befestigungsöffnung eines an der Anlagefläche anliegenden Werkzeugs ausgebildet ist und
• mit einem Befestigungsmittel zur Befestigung des Werkzeugs mit seiner Befestigungsöffnung an der Aufnahme.

The present invention relates to an oscillation drive with

• an output shaft, which is drivable to oscillate about its longitudinal axis and has a free end,
• a receptacle at the free end of the output shaft, which has a contact surface for the application of a tool,
• a fastening portion on the receptacle, which protrudes outwards in relation to the contact surface in the direction of the longitudinal axis and which is designed for the positive connection with a fastening opening of a voltage applied to the contact surface tool and
• with a fastening means for fastening the tool with its attachment opening on the receptacle.

Such an oscillation drive is from the US 6,945,862 B2 known.

An oscillation drive is to be understood as meaning a drive whose output shaft executes an oscillating rotational movement during operation. A fixed to the output shaft tool can be used in a variety of ways, such as for sawing, cutting or grinding.

Basically, two ways are known to connect the tool with the output shaft. In a first variant, the tool is pressed with a clamping element, for example by means of a clamping screw, against a receptacle at the free end of the output shaft, so that a high frictional force between the tool and the recording arises. Such a connection is referred to as frictional.

In a second variant, the receptacle or the tool on a mounting portion which can engage in a correspondingly shaped mounting opening on the other part. The transmission of the torque is achieved here by a form fit between the mounting portion and mounting hole. A positive connection offers over a frictional connection the advantage that even very high torques can be transmitted.

In continuous operation of oscillating drives, however, certain disadvantages have also been shown in the transmission of high torques to the tools. Thus, the mounting holes can be partially expanded. Also, after prolonged operation, heating of the tools by the oscillation drive was observed.

Against this background, it is an object of the present invention to provide an improved oscillation drive, which reduces the disadvantages of a positive torque transmission to the tool.

This object is achieved with an oscillatory drive of the type mentioned, in which the tool received on the mounting portion under the action of a torque against a bias axially yielding is and the attachment portion allows for axial deflection of the tool, a rotation of the tool by a certain angle of rotation.

Thus, the above task is completely solved.

The oscillation drive according to the invention combines the advantages of a positive connection, namely the possibility of transmitting high torques, with the advantages of a frictional connection, namely that overloads are avoided.

According to the invention, the transmission of the torque takes place in principle positive fit by a positive connection between the mounting portion of the output shaft and the mounting opening of the tool.

Now, if the load of the oscillation drive increases, so the oscillation drive according to the invention allows a certain axial deflection of the tool with respect to the longitudinal axis of the output shaft. Due to the axial deflection of the tool, the tool moves into a region of the mounting portion, which allows a rotation of the tool by a certain angle of rotation.

This results in a high degree of resilience, which allows a certain relative movement of the tool relative to the output shaft. This reduces torque peaks. As a result, the risk of heat generation is simultaneously reduced by the torque transmission and avoiding knocking the mounting hole.

The newly created possibility that the tool yield axially relative to the contact surface and can rotate by a certain angle of rotation leads to a division of the force acting in the oscillation plane against the fixing portion force into two components, namely in an axially acting force component, due to the tool in response, axially against the fastener pushes, and in a remaining, acting in the plane of oscillation force component.

If the load acting on the tool returns, the fastening means presses the tool back into its form-fitting starting position. The force which opposes the fastening means of the axial displacement of the tool is achieved in that the fastening means has an elastic and / or resilient part or is elastically and / or resiliently received.

Already at rest, the fastener elastically and / or resiliently presses against the tool and holds it in positive fit. At high load, the tool presses against the force exerted by the fastener, so that in a sense a part of the force acting on the attachment portion force is directed against the fastener , The axial deflection of the tool increases the force exerted by the fastener force and pushes the tool back into the secure positive fit as soon as the increased load decreases.

In one embodiment of the invention, the attachment portion widens in a direction parallel to the longitudinal axis and on the contact surface to at least in one area.

The width of the attachment portion is determined in a plane perpendicular to the longitudinal axis and measured along a circular arc whose center lies on the longitudinal axis. The widening of the fastening section in the direction of the contact surface can thus be described such that the width of the fastening section in a first plane perpendicular to the longitudinal axis is greater than the width in a parallel plane which is farther away from the contact surface than the first plane.

In other words, this means that the attachment portion narrows or tapers in at least one region away from the contact surface in one direction.

In particular, this may mean that the base surface of the fastening section, with which the fastening section rests on the contact surface, is larger than the surface of the fastening section facing away from the base surface. If the surfaces mentioned are not flat, the respective surface dimension is to be considered in relation to a plane perpendicular to the longitudinal axis.

In a further embodiment of the invention, the attachment portion has a plurality of projections which protrude radially outwardly with respect to the longitudinal axis.

By means of such projections of the positive fit and the desired torque transmission can be realized particularly well.

In a further embodiment of the invention, each projection forms, starting from the contact surface, at least one flank whose base line is a straight path on the contact surface.

In this case, a corresponding contact surface should also be formed with a straight base line at the attachment opening of the tool. Then the torque transmission can take place along the entire straight line. This can eliminate punctiform stresses between the fastener and the mounting hole, so that areas with a particularly high heat load can be avoided.

In a further embodiment of the invention, the surface of the flank forms a flat trapezoid.

If the surface of the flank is designed in such a way, upon rotation of the tool a particularly good sliding of the part of the fastening opening corresponding to this flank is possible. Furthermore, it is advantageous in this embodiment that the sliding of the part of the attachment opening and thus the axial Dodge of the tool is approximately proportional to the force acting on the tool in the oscillation plane. That is, the higher the load on the tool, the further the tool can yield axially.

In a further embodiment of the invention, the flank to the longitudinal axis forms an angle between 5 ° and 40 °, preferably between 10 ° and 25 °, in particular between 13 ° and 17 °. The angle can be chosen in view of the intended material pairing, e.g. Steel on steel or steel on aluminum.

In this angular range, a good balance is ensured between on the one hand a secure form-fitting transmission of torque and on the other hand, the desired compliance in the direction of rotation under heavy load.

In a further embodiment of the invention, the output shaft on a biased by a spring element tension element on which the fastening means can be fixed.

In this embodiment, the fastening means, for example, a fastening pin, held by the substantially rigid tension member, wherein the tension element is in turn held by means of the spring element resiliently in the oscillation drive. The principle of such a structure is for example from the DE 39 02 874 A1 known.

In a further embodiment of the invention, the fastening means on an elastic and / or resilient portion.

In this embodiment, the tool is held by a member that allows the axial deflection of the tool due to a partially elastic and / or resilient property. Such a fastening means can for example represent a clamping screw whose screw head has a certain elasticity or is elastically displaceable with respect to the screw shaft.

In a further embodiment of the invention, the attachment portion is polygonal in cross-section, preferably formed hexagonal.

In a further embodiment of the invention, the projections are symmetrical with respect to a direction radial to the longitudinal axis and each have two flanks, which are connected to each other via a remote from the longitudinal axis, common, curved portion.

In a further embodiment of the invention, the flanks approach at an angle between 5 ° and 35 °, preferably between 10 ° and 25 °, in particular between 12 ° and 18 °.

In a further embodiment of the invention, the flanks of the projections are closed in an area near the longitudinal axis by an undercut.

As a result, it can be achieved that the torque transmission does not take place in the innermost region of the projection, which is seen radially from the longitudinal axis, but in its middle, and possibly also in its outer region.

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

Fig. 1a

eine Aufnahme eines Oszillationsantriebs in einer Seitenansicht;

Fig. 1b

eine Vergrößerung der Aufnahme gemäß Fig. 1a;

Fig. 2a

die Aufnahme gemäß Fig. 1a, aufweisend vier Vorsprünge, in der Seitenansicht;

Fig. 2b

eine Ausschnittsvergrößerung eines Vorsprungs gemäß Fig. 2a;

Fig. 3

die Aufnahme gemäß Fig. 1a mit einem angelegten Werkzeug;

Fig. 4

einen Schnitt längs der Linie IV-IV durch die Aufnahme gemäß Fig. 1a mit aufgesetztem Werkzeug und eingesetztem Befestigungsmittel;

Fig. 5a

die Aufnahme gemäß Fig. 4, bei der das Werkzeug axial ausgewichen ist und sich um einen gewissen Verdrehwinkel verdreht hat;

Fig. 5b

eine Ausschnittsvergrößerung der Aufnahme gemäß Fig. 5a;

Fig. 6a

eine alternative Ausführungsform der Aufnahme mit einem Befestigungsabschnitt in der Form eines Sechskants in der Seitenansicht; und

Fig. 6b

die Ausführungsform gem. Fig. 6a in der Draufsicht.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. Show it:

Fig. 1a

a recording of a Oszillationsantriebs in a side view;

Fig. 1b

an enlargement of the picture according to Fig. 1a ;

Fig. 2a

the recording according to Fig. 1a comprising four projections, in side view;

Fig. 2b

an enlarged detail of a projection according to Fig. 2a ;

Fig. 3

the recording according to Fig. 1a with a designed tool;

Fig. 4

a section along the line IV-IV through the inclusion according to Fig. 1a with attached tool and inserted fastener;

Fig. 5a

the recording according to Fig. 4 in which the tool has evaded axially and has rotated by a certain angle of rotation;

Fig. 5b

an enlarged detail of the recording according to Fig. 5a ;

Fig. 6a

an alternative embodiment of the recording with a mounting portion in the form of a hexagon in the side view; and

Fig. 6b

the embodiment acc. Fig. 6a in the plan view.

Fig. 1a shows an oscillating drive 10 with an output shaft 12 which is driven to oscillate about its longitudinal axis 14 and has a free end 16. At the free end 16, a receptacle 18 is arranged, which has a contact surface 20 for engaging a tool 22 (FIG. Fig. 3 ) having. A section of the receptacle 18 is in the Fig. 1b shown enlarged.

On the receptacle 18, a fastening portion 24 is arranged, which protrudes outwards in relation to the contact surface 20 in the direction of the longitudinal axis 14 to the outside and for the positive connection with a mounting opening 26 (FIG. Fig. 3 ) of a voltage applied to the contact surface 20 tool 22 is formed.

The oscillating drive 10 also has a quick-release device 29 with a tensioning lever 30, by means of which a tension element 31 received in the output shaft 12 can be axially displaced between a working position and a rest position. On the tension element 31, a fastening means 28 can be fastened approximately in the form of a screw, which passes through a fastening opening 26 of a tool 22 placed on the fastening section 24.

In the rest position, the tension element 31 is pushed axially outwardly by the tensioning lever 30, so that in this position the fastening means 28 can be released without the aid of a hand tool in order to change the tool 22. When moving the clamping lever 30, the tension element 31 reaches the working position, in which now the tension element 31 is stretched by the action of a spring element 32, so that the fastening means 28 and thus the tool 22 under the action of the spring element 32 against the contact surface 20 of the recording 18 is biased.

The fastening means 28 is here indicated in the form of a pin 34 inserted into the tension element 31 with a head 35.

In particular, if the oscillation drive 10 no quick-release device 29 - and thus no spring element 32 - has, but it is also conceivable, for example, the edge of the head 35 compliant form, so that an axial deflection of the tool 22 is possible and the head 35 of the pin 34 then exerts a restoring force on the tool 22.

The resilient attachment of the fastener 28 results in that the fastener 28 can also be displaced against the force exerted by the spring element 30, i. away from the contact surface 20, when a correspondingly large force is exerted on the fastening means 28.

As a result, either the pulling element 31 or the fastening means 28 permits axial deflection of the tool 22. The force required to move counter to Preloading the fastener 28 results from the torque acting between the output shaft 12 and the tool 22, as will be explained in more detail below.

The attachment portion 24 here has four projections 36, which are each arranged at an angle of 90 ° to each other about the longitudinal axis 14. (One of the projections 36 is hidden here.) The projections 36 are each connected via a concentric to the longitudinal axis 14 arc-like portion 44. Overall, it should be noted that the attachment portion 24 widens in a direction parallel to the longitudinal axis 14 and on the contact surface 20.

As in the synopsis with the Fig. 2a and 2b , which show the receptacle 18 in a plan view and an enlarged view of a projection 34, the projections 36 are symmetrical with respect to a radial direction to the longitudinal axis 14 and each have two flanks 38, which facing away from the longitudinal axis 14 , common, curved portion 42 are interconnected. The baseline 40 of the flanks 38 on the contact surface 20 is in each case a straight line.

The flanks 38 form in a side view approximately according to Fig. 1a, b each a flat harness. The angle α formed by a flank 38 to the longitudinal axis 14 is here about 15 °. The angle β at the rounding of the projection 36 is here also about 15 °, but if necessary, it can also be selected differently from the angle α.

Like in the Fig. 2b can be seen particularly well, the projection 36 tapers in the radial direction from the longitudinal axis 14 to the outside. The taper is achieved by the planar flanks 38 approaching radially outward. The angle γ between the two flat flanks 38 is approximately 15 ° here.

In addition to the said taper, the flanks 38 of the projections 36 are in an area near the longitudinal axis 14 in each case by an undercut 46 completed. This can cause the power transmission between the output shaft 12 and the tool 22 takes place mainly or exclusively along the flanks 38.

Fig. 3 shows the oscillating drive 10 with attached tool 22. The mounting hole 26 has eight receptacles, the shape and size of the projections 36 is adapted so that the tool 22 - as shown by the dashed line - can be placed in different positions. The oscillation direction of the oscillation drive 10 is indicated by means of the double arrow 48.

When the tool 22 bears against the abutment surface 20, a positive connection is created between the attachment section 24 and the attachment opening 26. A possible angle of rotation δ is shown symbolically. It should be noted that the twist angle δ shown here is greatly exaggerated for the purpose of explanation and that the actually occurring twist angle δ is significantly smaller, in particular of the order of less than 1 °. The maximum theoretically possible angle of rotation δ is limited by the design of the quick-action clamping device 29 or of the fastening means 28, since in a final position, a positive connection is again achieved. In practice, however, due to the oscillations with high frequency (~ 5000 - 30,000 oscillations per minute) and small pivoting angle (0.5 ° - 7 °) only very small angle of rotation δ.

Fig. 4 shows the receptacle 18 with an attached tool 22, wherein the tool 22 is pressed by the fastening means 28 against the contact surface 20.

It can be seen that edges 50 of the attachment opening 26 of the tool 22 in the region of the baseline 40 abut the projection 36. In this way, a positive transmission of the torque from the output shaft 12 takes place on the tool 22.

The situation that arises when the tool 22 is subjected to a high load is in the Fig. 5a and 5b shown, the receptacle 18 and an enlarged section of the receptacle 18 show.

It can be seen that the tool 22 has lifted off the contact surface 20 in the axial direction. Again, the axial displacement for the purpose of better visibility is greatly exaggerated. The oblique flank 38 causes the force which hitherto has been applied in a plane perpendicular to the longitudinal axis 14 to the fastening section 24, in particular to the projections 36, to be partially converted into a force acting axially to the longitudinal axis 14. This axially acting force is indicated by the arrow 52. The remaining, acting transversely to the longitudinal axis 14 force component is shown by the arrow 54.

The force acting on the tool 22 causes it to slide with its attachment opening 26 along the flank 38. In response to the axial force component 52, the tool 22 pushes against the bias of the fastener 28, while the force component 54 leads to the rotation of the tool 22 by the twist angle δ. The rotation can take place when the axial force component 52 exceeds the bias caused by the spring element.

When the load of the tool 22 decreases again or the oscillation goes in the other direction, the axial force component 52 decreases again, and the fastening means 28 again presses the tool 22 against the contact surface 20.

Due to the certain flexibility of the tool 22 at high torque torque peaks that occur due to the oscillating movement, degraded and thus counteracted heating of the tool 22 and a deflection of the mounting hole 26.

The compliance can be realized advantageously with an oscillating drive 10 with a quick-release device 28, since the existing spring element 32 can be used to achieve the axial mobility.

Fig. 6a and 6b show by way of example an alternative embodiment of the receptacle 18 with a mounting portion 24 in the form of a hexagon. Other irregular or regular polygons, in particular quadrilaterals or pentagons, may also be chosen.

Claims (12)

1. Oscillation drive (10) with:

   - an output shaft (12), which can be driven rotatingly and oscillatingly about its longitudinal axis (14) and which comprises a free end (16),

   - a flat mounting (18) at this free end (16) of the output shaft (12), which comprises a contact surface (20) for attachment of a tool (22),

   - a mounting section (24) at this flat mounting (18), which projects outwardly relative to the contact surface (20) in the direction to the longitudinal axis (14) and which is designed to connect by form-fit with a mounting opening (26) of a tool (22) , which rests against the contact surface (20) and

   - with a holding fixture (28) for fastening the tool (22) with its mounting opening (26) at the flat mounting (18),

   characterized in, that

   - the tool (22) is held at the mounting section (24) with axial resilience due to the effect of a torque against a preload and

   - the mounting section (24) permits a rotation of the tool (22) about a certain angle of rotation (δ) when the tool (22) yields axially.
2. Oscillation drive (10) according to claim 1, characterized in, that this mounting section (24) widens at least in a certain area in a direction parallel to the longitudinal axis (14) and toward the contact surface (20).
3. Oscillation drive (10) according to claim 1 or 2, characterized in, that the mounting section (24) comprises a plurality of lugs (36), which project radially outwardly relating to the longitudinal axis (14).
4. Oscillation drive (10) according to claim 3, characterized in, that each lug (36) forms at least one flank (38) starting from the contact surface (20), the baseline (40) of which is a straight line on the contact surface (20).
5. Oscillation drive (10) according to claim 4, characterized in, that the surface of the flank (38) forms a planar trapezoid.
6. Oscillation drive (10) according to claim 4 or 5, characterized in, that the flank (38) encloses an angle (α) between 5° und 40° with respect to the longitudinal axis (14), preferably between 10° and 25°, particularly between 13° and 17°.
7. Oscillation drive (10) according to one of the preceding claims, characterized in, that the output shaft (12) comprises a tensile element (31) which is preloaded by a spring element (32); the holding fixture (28) may be fixed to the tensile element (31).
8. Oscillation drive (10) according to one of the preceding claims, characterized in, that the holding fixture (28) comprises an elastic and/or resilient section.
9. Oscillation drive (10) according to one of the preceding claims, characterized in, that the mounting section (24) is designed with a polygonal, preferably hexagonal cross section.
10. Oscillation drive (10) according to one of the claims 3 to 8, characterized in, that the lugs (36) are formed symmetrically with respect to the longitudinal axis (14) in radial direction and
    comprise two flanks (38) each, which are interconnected by a common curved section (42) facing away from the longitudinal axis (14),
11. Oscillation drive (10) according to claim 10, characterized in, that the flanks (38) approach each other with an angle (γ) between 5° and 35°, preferably between 10° and 25°, especially between 12° and 18°.
12. Oscillation drive (10) according to claim 10 or 11, characterized in, that each of the flanks (38) of the lugs (36) are terminated by an undercut in an area close to the longitudinal axis (14).

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