DE102007014757A1 - Rotary percussion - Google Patents

Abstract

The invention relates to a rotary percussion mechanism (1) for an electric tool, having a drivable rotary percussion weight (3) with at least one hammer surface (15), and having an anvil (16) that can be rotated with the rotary percussion weight (3) about a common rotational axis (13) and is operatively connected to a tool shaft (2) to transmit torque, said anvil having at least one anvil surface (16). Said rotary percussion mechanism also has a displacement mechanism comprising a return spring (9), said mechanism being designed to cause a combined relative motion in the axial and circumferential directions under tension of the return spring (9) between the rotary percussion weight (3) and the anvil (10), resulting in a percussion effect of the hammer surface (15) on the anvil surface (16) in the circumferential direction, when the tool shaft (2) demands increased torque. According to the invention, the tool shaft (2) is axially displaceably supported, and the anvil surface (16) and/or the hammer surface (15) is/are aligned and/or designed such that a percussion of the hammer surface (15) on the anvil surface (16) results in a displacement of the tool shaft (2) in the axial direction, in addition to a rotary impulse on the tool shaft (2) in the circumferential direction.

Description

State of the art

The Invention relates to a rotary impact mechanism for a power tool, in particular an electric hand tool according to the Preamble of claim 1.

Such rotary impact devices are used exclusively in impulse wrenches and rotary impact wrenches (impact wrenches). An example of a rotary impact wrench with a rotary impact mechanism is in the DE 147 88 09 disclosed. With rotary impact drives, a distinction is made between three basic types, namely cam followers, V-groove impactors and hydraulic pulse impactors. Rotary tappets enable the release of high torques with relatively low power input in almost torque-free manner. Furthermore, they are characterized by the fact that they convert the continuous power output of the drive motor in a punch-shaped angular momentum, the energy output of the engine is stored in a rotational impact weight and abruptly transmitted by means of a pulse of high power intensity on a non-rotatably mounted on a tool shaft supporting a screwing anvil , Another advantage of rotary impact is that they are compact and inexpensive to produce.

In Percussion drills are usually used Rastenschlagwerke, the in contrast to the rotary impact no angular momentum in the circumferential direction generate on the tool shaft, but exclusively an adjustment pulse in the axial direction. Have Rastenschlagwerke the advantage that they are extremely simple and are inexpensive to produce. In practice, prove However, these are not very effective (low impact). More powerful mechanical impact devices for impact drills are for example so-called Massenschlagwerke, whose structure is very complex and these therefore only costly to produce and assemble.

Disclosure of the invention

Technical task

Of the Invention is therefore based on the object, a rotary impact mechanism for to modify the use in a percussion drill.

Technical solution

These The object is achieved with the features of claim 1. Advantageous developments of the invention are in the dependent claims specified. The scope of the invention also includes all combinations at least two of the in the description, the claims and / or the figures specified characteristics.

Of the Invention is based on the idea that at least one hammer surface and / or to align the at least one anvil surface in such a way or to sculpt that by striking the hammer surface on the Anvil surface in addition to the angular momentum in the circumferential direction generates a force acting in the axial direction of the tool shaft force component is, which ensures that the adjustable in the axial direction Tool shaft, which preferably carries a drill chuck with a drilling tool, accelerated in the direction of the workpiece to be machined becomes. By this modification over known rotary impact works can the rotary impact mechanism according to the invention for generating a beating Bohrervortriebs be used. The turning energy the rotational impact weight is doing u. a. for generating the axial Power component exploited. The preferred oblique or curved alignment or shaping of the hammer surface and / or the anvil surface ensures a division the angular momentum in an axial and in a peripheral component. The rotary impact mechanism according to the invention is extremely powerful and requires little space. About that In addition, the rotary impact is inexpensive to produce. The claimed rotary impact mechanism can even without a gear ratio have to provide a large speed range at the same time cover high torques and works efficient and non-kickback, even in hard building materials like concrete or rock. The drilling action is in addition to the axial stroke of the circumferentially acting impact component supported.

The Drehschlagwerk can be with all known adjustment mechanisms, such as a cam mechanism, a slanted groove mechanism, in particular a V-groove mechanism, or one in particular hydraulic impulse mechanism, train.

An advantage is an embodiment in which at an increased torque requirement by the tool or by the tool shaft and an associated rotation speed reduction of the tool shaft by means of an adjusting mechanism relative movement between the rotational impact weight and the anvil, which is preferably permanently coupled torque transmitting with the tool shaft, in particular rotatably connected thereto, effected in the axial and in the circumferential direction, whereby from the rotational movement of the rotational impact weight out a collision between the hammer surface and the anvil surface is provoked. Preferably, the tool shaft is such, in particular between two axial stops, axially ver adjustable, that by a rotary impact axial displacement of the tool by at least two, preferably at least three, in particular at least five millimeters, or more results.

In Embodiment of the invention is provided with advantage that the axial force component is achieved on the tool shaft thereby that the hammer surface with an imaginary, orthogonal to the Rotary axis of the tool shaft and the rotary impact weight, in particular through the anvil, extending plane an angle α ≠ 90 ° stretched becomes. By choosing the angle α while the ratio be set between angular momentum and axial momentum.

additionally or alternatively, it is provided in a further development of the invention that the anvil surface opposite the orthogonal to the Rotary axis extending plane inclined at an angle β ≠ 90 ° is, so with this plane an angle β ≠ 90 ° includes.

To minimize the wear of the hammer surface and the anvil surface, it is advantageous if the angular relationship α = 180 ° - β applies.

Next a planar formation of the anvil surface and / or the hammer surface is also a curved training conceivable, with preference the hammer surface and the corresponding anvil surface in the same direction and with the same radius of curvature are curved, so at least approximately congruent shape are formed.

It has proved to be advantageous if the angle α at least approximately from an angular range between 5 ° and 85 °, in particular at least approximately between 15 ° and 75 °, preferably at least approximately between 25 ° and 65 °, preferably between 35 ° and 55 °, is chosen, or more preferably about 45 °. At an angle α of 45 ° while the impact energy split at least approximately half for generating a shock pulse in the axial direction and the Generation of a shock pulse in the circumferential direction. The angle β is thereby preferably 180 ° - α.

to Increasing the beat rate is provided with advantage that the anvil several inclined in the same direction anvil surfaces and / or the rotational impact weight inclined more in the same direction Has hammer surfaces.

Around both in a rotational speed driven in a left direction of rotation as well as when driven in a right-hand direction rotational speed a striking effect in the axial direction, d. H. a shock pulse to realize the tool shaft in the axial direction, it is of Advantage, if the anvil at least two in opposite directions Direction inclined anvil surfaces and / or the rotational impact weight inclined at least two in opposite directions Has hammer surfaces. Preferably, they are both each other oppositely inclined anvil surfaces and both each other oppositely inclined hammer surfaces on each one Axial projection of the anvil or the Schlagschlaggewichts.

Around the ratio between the axial impact pulse and the circumferential impact pulse to be able to vary, it is beneficial if at least an adjustment mechanism for varying the angle α or the angle β is provided. This adjusting mechanism is preferred formed such that also an angle α and / or a Angle β of at least approximately 90 ° adjustable is such that no axial impact pulse results on the tool shaft and equipped with the rotary impact power tool as Rotary impact driver is used.

With Advantage is a further embodiment of the rotary impact mechanism, in which the adjusting mechanism can be blocked or bridged is, preferably such that at an increased torque request no impact pulse is triggered by the tool shaft. Through this development, it is possible to use the rotary impact mechanism equipped power tool in pure drilling operation (pure turning operation) use without hammer operation.

From Advantage is a construction in which the tool shaft, in particular together with the anvil by means of a, in particular as a coil spring trained, spring in the direction of an axial stop Federkraftbeaufschlagt is, wherein the axial stop preferably at the free end of the tool shaft is arranged opposite end. The spring serves as a return spring for Verstel len of the tool shaft in its initial position after completed axial movement.

Further Advantages, features and details of the invention will become apparent the following description of preferred embodiments as well as from the drawings; these show in:

1 a rotary impact mechanism configured exclusively for anti-clockwise rotation with an adjusting mechanism designed as a cam mechanism in a position at the beginning of an increased torque requirement by a tool shaft,

2 the rotary impact mechanism according to 1 in a position in which the rotary impact weight with its hammer surface a stroke in the circumferential direction against an anvil surface of the rotatably connected to the tool shaft anvil applies, and

3 a schematic representation of essential components of a rotary impact mechanism, which can perform both in a left and in a right-hand rotational direction rotational shocks with an axial force component.

embodiments the invention

In The figures are the same components and components with the same Function marked with the same reference numerals.

In the figures is a trained as a cam impact turning mechanism shown. Alternatively, the rotary impact mechanism as Schrägnuten-, in particular V-Nutenschlagwerk, or be designed as a pulse impact. Further control or adjustment mechanisms are also conceivable. The Training the rotary impact mechanism as a V-groove impact mechanism would have the advantage that the energy stored in the rotary impact weight quasi free from the drive motor of a spring in the wire direction accelerate can. In a cam follower described by way of example below becomes a part of the stored energy to accelerate the drive motor used.

This in 1 shown rotary impact mechanism 1 includes a tool shaft 2 , at the upper, free end in the drawing plane, for example, a drill chuck is arranged with a drill tool. Coaxial to one with the tool shaft 2 aligned and with the tool shaft 2 positively connected camshaft 19 is a rotary impact weight 3 arranged, with an external spline 4 is provided. By means of a drive motor, not shown, whose motor shaft with a longitudinal toothing 4 is formed congruent longitudinal toothing, with the longitudinal teeth 4 of the rotational impact weight 3 is engaged (not shown), the rotational impact weight 3 in the direction of the arrow 5 (counterclockwise) driven.

On the camshaft 18 sits non-rotatably a cam disc 6 with cams 7 , About a ball 8th the rotational impact weight is supported 3 on the cam disc 6 from where the rotational impact weight 3 by means of a return spring 9 , which at one end to a rotationally fixed on the tool shaft 2 arranged anvil 10 (Anvil disk) and at the other end on an annular shoulder 11 the rotational impact weight 3 supported in the axial direction on the cam 6 spring force.

As long as the tool shaft 2 (with drilling tool) provides no major resistance, the biasing force of the return spring is sufficient 9 from that the rotational impact weight 3 over the ball 8th the cam disk 6 and thus the camshaft 18 and thus the tool shaft 2 in the direction of the arrow 12 turns (left-hand rotation). Turning turn weight 3 , Tool shaft 2 and camshaft 18 around a common axis of rotation 13 ,

As the resistance increases during drilling, the torque requirement of the tool shaft increases 2 , then reduces the rotational speed of the tool shaft 2 and due to the positive connection with the camshaft 18 , also the rotational speed of the camshaft 18 , whereby these possibly even come to a standstill. The driven, revolving rotational impact weight 3 is done by rolling the ball 8th over the cam 7 against the spring force of the return spring 9 on the camshaft 18 forward in the direction of the arrow 19 pressed. Reach the ball 8th the front edge 14 of the cam 7 , beats an oblique hammer surface 15 the rotational impact weight 3 on an anvil surface 16 of the anvil 10 , The hammer surface 15 is opposite to an orthogonal to the axis of rotation 13 and through the anvil 10 extending plane E inclined by about 45 °. The anvil surface encloses with the plane E an angle β = 180 ° - 45 ° = 135 °. Due to the inclination of the surfaces 15 . 16 the anvil experiences 10 and thus the tool shaft 2 not just one angular momentum in the circumferential direction (arrow directions 5 . 12 ), but also in the axial direction 17 , causing the tool shaft 2 in the axial direction 17 is adjusted and thus an axial impact is exerted on the workpiece to be machined.

The positive connection between the camshaft 18 and tool shaft 2 is preferably designed such that the positive connection during the axial movement of the tool shaft 2 and the axially differently mounted camshaft 18 does not solve.

After a completed blow will be the Schlagschlaggewicht 3 and the ball 8th by the return spring 9 at the back 20 of the cam 7 on the cam disk 6 the camshaft 18 pushed back again, leaving the hammer area 15 on the anvil surface 16 can turn over. After one revolution (in a single-cam impact mechanism), the rotational impact weight hits 3 again by means of his ball 8th on the nock 7 the camshaft 18 , whereby the sequence described repeats itself.

In 2 is shown as the inclined at an angle α of about 45 ° to the plane E hammer surface 15 and the anvil surface inclined to the plane E at an angle β of about 135 ° 16 to beat each other.

In 3 is only a section of the tool shaft 2 with anvil 10 and a section of the rotational impact weight 3 shown. It can be seen that the rotational impact weight 3 two mutually oppositely inclined hammer surfaces 15 both enclosing with the plane E an angle α of about 65 °. The anvil is corresponding 10 with two mutually oppositely inclined hammer surfaces 16 provided, each with the plane E an angle β of about 115 ° span. The angular relationship α = 180 ° - β applies here. The shown rotary impact mechanism 1 can both axial clockwise and clockwise axial impact on the tool shaft 2 generating operated.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - DE 1478809 [0002]

Claims (12)

Rotary impact mechanism for a power tool, with a drivable rotational impact weight ( 3 ) with at least one hammer surface ( 15 ), and one with the rotational impact weight ( 3 ) about a common axis of rotation ( 13 ) rotatable and with a tool shaft ( 2 ) torque transmitting active connected anvil ( 10 ) with at least one anvil surface ( 16 ), on which the hammer surface ( 15 ) is arranged to act in a striking manner in the circumferential direction, characterized in that the tool shaft ( 2 ) is mounted axially adjustable, and that the anvil surface ( 15 ) and / or the hammer surface ( 16 ) are aligned and / or formed such that by a blow of the hammer surface ( 15 ) on the anvil surface ( 16 ) next to an angular momentum on the tool shaft ( 2 ) in the circumferential direction an adjustment of the tool shaft ( 2 ) in the axial direction ( 17 ) results. Rotary impact mechanism according to claim 1, characterized in that the rotary impact mechanism ( 1 ) with a return spring ( 9 ) is provided, which at an increased torque requirement of the tool shaft ( 2 ) under tension of the return spring ( 9 ) between the rotational impact weight ( 3 ) and the anvil ( 10 ) a combined relative movement in the axial and in the circumferential direction and in consequence the impact effect of the hammer surface ( 15 ) in the circumferential direction on the anvil surface ( 16 ) is formed effecting. Rotary impact mechanism according to one of claims 1 or 2, characterized in that the anvil surface ( 15 ) with respect to an orthogonal to the axis of rotation ( 13 ) extending plane (E) is inclined at an angle (α) of not equal to 90 °. Rotary impact mechanism according to one of claims 1 to 3, characterized in that the anvil surface ( 16 ) with respect to the orthogonal to the axis of rotation ( 13 ) extending plane (E) at an angle (β) of not equal to 90 ° is inclined. Rotary impact mechanism according to claim 4, characterized that at least approximately α = 180 ° - β. Rotary impact mechanism according to one of the preceding claims, characterized in that the angle α between the hammer surface ( 15 ) and the orthogonal to the axis of rotation ( 13 ) extending plane (E) at least approximately between 5 ° and 85 °, in particular at least approximately between 15 ° and 75 °, preferably at least approximately between 25 ° and 65 °, preferably between 35 ° and 55 °, more preferably about 45 °. Rotary impact mechanism according to one of the preceding claims, characterized in that the angle (β) between the anvil surface ( 16 ) and the orthogonal to the axis of rotation ( 13 ) extending plane (E) at least approximately between 95 ° and 175 °, in particular at least approximately between 105 ° and 165 °, preferably at least approximately between 115 ° and 155 °, preferably between 125 ° and 145 °, particularly preferably about 135 °. Rotary impact mechanism according to one of the preceding claims, characterized in that the anvil ( 10 ) a plurality of inclined in the same direction anvil surfaces ( 16 ) and / or the rotational impact weight ( 3 ) a plurality of hammer surfaces inclined in the same direction ( 15 ) having. Rotary impact mechanism according to one of the preceding claims, characterized in that the anvil ( 10 ) at least two inclined in opposite directions inclined anvil surfaces ( 16 ) and / or the rotational impact weight ( 3 ) at least two mutually opposite directions inclined hammer surfaces ( 15 ) having. Rotary impact mechanism according to one of the claims 3 to 9, characterized in that the angle (α) and / or the angle (β) adjustable by means of an adjusting mechanism are / is. Rotary impact mechanism according to one of the claims 2 to 10, characterized in that a blocking device for overriding and / or a bridging device provided for bridging the adjusting mechanism is. Rotary impact mechanism according to one of the preceding claims, characterized in that the tool shaft ( 2 ) by means of a spring in the direction of a camshaft ( 18 ) is spring-loaded.