EP2132005B1 - Rotary percussion mechanism - 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 percussion drill according to the preamble of claim 1.

Such percussion drill is from the US 2006/0024141 A1 known. The known percussion drill has a braking means to activate during drilling operation activation of the rotary impact mechanism already at low without already without contact force of the machine to a workpiece.

From the US 2,049,273 Furthermore, an impact wrench with a rotary impact mechanism is known, which has a rotary impact mechanism with hammer and anvil surfaces, which are arranged obliquely relative to a plane extending orthogonally to the axis of rotation. Exact angle information regarding the arrangement of the hammer and anvil surfaces of the font, however, are not apparent. In addition, the rotary impact of an impact wrench usually has a much lower speed than that of a drill or impact drill.

Another example of such a rotary impact mechanism in a rotary impact driver is in 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 impact devices enable the release of high torques at relatively low power input in almost Rückdrehmomentsfreie way. 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 carrying a screwing anvil , Another advantage of rotary impact is that they are compact and inexpensive to produce.

In impact drills mostly Rastenschlagwerke be used, which unlike the rotary impact produce no angular momentum in the circumferential direction of the tool shaft, but only an adjusting pulse in the axial direction. Rastenschlagwerke have the advantage that they are extremely simple and inexpensive to produce. In practice, however, these prove to be less effective (low impact). More powerful mechanical percussion for impact drills, for example, so-called mass impact, the structure of which is very complex and therefore expensive to produce and assemble.

The invention has the object of providing a percussion drill according to the preamble of claim 1 such that this allows a simple as possible structural design a punch-shaped angular momentum and an impulse in the longitudinal axis of the tool, the pulses in the usually used tools and materials to be processed enable the most effective and tool-friendly machining should. This object is achieved in a hammer drill with the features of claim 1. Advantageous developments of the invention are specified in the subclaims.

The rotary impact mechanism can be formed with all known adjustment mechanisms, such as a cam mechanism, a Schrägnuten mechanism, in particular a V-groove mechanism.

Advantageous 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 a 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, causes in the axial and 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 axially adjustable in such a way, in particular between two axial stops, that a rotational displacement results in an axial displacement of the tool by at least two, preferably at least three, in particular at least five millimeters, or more.

In addition to a planar design of the anvil surface and / or the hammer surface and a curved training is conceivable, preferably the hammer surface and the corresponding anvil surface in the same direction and with the same Curvature radius are curved, so are formed at least approximately congruent shape.

In order to increase the impact frequency, it is advantageously provided that the anvil has a plurality of anvil surfaces inclined in the same direction and / or the rotational impact weight has a plurality of hammer surfaces inclined in the same direction.

In order to realize a hammering action in the axial direction, ie a shock pulse on the tool shaft in the axial direction, both in a rotational speed driven in a left direction of rotation as well as a driven in a right direction of rotation rotational impact, it is advantageous if the anvil at least two in has opposing directions inclined anvil surfaces and / or the rotational impact weight at least two mutually opposite directions inclined hammer surfaces. Preferably, both mutually oppositely inclined anvil surfaces and both mutually oppositely inclined hammer surfaces are each at an axial projection of the anvil and the rotational impact weight.
Advantageously, another embodiment of the rotary impact mechanism, in which the adjusting mechanism can be blocked or bridged, preferably such that at an increased torque request by the tool shaft no impact pulse is triggered. With this development, it is possible to use a power tool equipped with the rotary impact mechanism in the pure drilling operation (pure rotary operation) without hammer operation.

An advantage is a construction in which the tool shaft, in particular together with the anvil by means of a, in particular designed as a helical spring, in Direction to an axial stop spring force is applied, wherein the axial stop is preferably disposed at the opposite end of the free end of the tool shaft. The spring serves as a return spring for adjusting the tool shaft in its initial position after completed axial movement.

Fig. 1

ein ausschließlich für den Linkslauf konfiguriertes Drehschlagwerk mit einem als Nockenmechanismus ausgebildeten Verstellmechanismus in einer Position zu Beginn einer erhöhten Drehmomentanforderung durch eine Werkzeugwelle,

Fig. 2

das Drehschlagwerk gemäß Fig. 1 in einer Position, in der das Drehschlaggewicht mit seiner Hammerfläche einen Schlag in Umfangsrichtung gegen eine Ambossfläche des drehfest mit der Werkzeugwelle verbundenen Ambosses ausübt, und

Fig. 3

eine schematische Darstellung wesentlicher Komponenten eines Drehschlagwerkes, welches sowohl bei einer linken als auch bei einer rechten Drehrichtung Drehschläge mit einer Axialkraftkomponente ausführen kann.

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

Fig. 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,

Fig. 2

the rotary impact mechanism according to Fig. 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

Fig. 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 of the invention

In the figures, the same components and components with the same function with the same reference numerals.

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

This in Fig. 1 shown rotary impactor 1 comprises a tool shaft 2, at the upper level in the plane of the drawing, for example, a drill chuck is arranged with a drill tool. Coaxially with a camshaft 19 which is aligned with the tool shaft 2 and is positively connected with the tool shaft 2, a rotary impact weight 3 is arranged which is provided with an outer longitudinal toothing 4. By means of a drive motor, not shown, the motor shaft is formed with a longitudinal toothing 4 conforming to the longitudinal toothing, which is engaged with the longitudinal teeth 4 of the rotary impact weight 3 (not shown), the rotational impact weight 3 in the direction of arrow 5 (left-handed) driven.

About a ball 8, the rotational impact weight 3 is supported on the cam 6, wherein 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 10th (Anvil disk) and at the other end at one Ring shoulder 11 of the rotary impact weight 3 is 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 9 is sufficient that the rotary impact weight 3 on the ball 8, the cam 6 and thus the camshaft 18 and thus the tool shaft 2 rotates in the direction of arrow 12 (left-hand rotation). Rotational impact weight 3, tool shaft 2 and camshaft 18 rotate about a common axis of rotation 13.

Increases the resistance during drilling, so increases the torque requirement of the tool shaft 2, then reduces the rotational speed of the tool shaft 2 and due to the positive connection with the camshaft 18, and the rotational speed of the camshaft 18, thereby possibly even come to a standstill. The driven, further rotating rotational impact weight 3 is pressed by rolling the ball 8 via the cam 7 against the spring force of the return spring 9 on the camshaft 18 forward in the direction of arrow 19. When the ball 8 reaches the front edge 14 of the cam 7, an oblique hammer surface 15 of the rotary impact weight 3 strikes an anvil surface 16 of the anvil 10. The hammer surface 15 is approximately 45 ° relative to a plane E orthogonal to the axis of rotation 13 and through the anvil 10 ° inclined. The anvil surface encloses with the plane E an angle β = 180 ° - 45 ° = 135 °. Due to the inclination of the surfaces 15, 16 of the anvil 10 and thus the tool shaft 2 learns not only an angular momentum in the circumferential direction (arrows 5, 12), but also in the axial direction 17, whereby the tool shaft 2 in the axial direction 17th is adjusted and thus an axial impact is exerted on the workpiece to be machined.

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

After a completed blow the rotational impact weight 3 and the ball 8 are pushed back by the return spring 9 on the back 20 of the cam 7 on the cam 6 of the camshaft 18, so that the hammer surface 15 can rotate past the anvil surface 16 past. After one revolution (in a single-cam impact mechanism), the rotational impact weight 3 hits again by means of its ball 8 on the cam 7 of the camshaft 18, whereby the sequence described repeated.

In Fig. 2 It is shown how the inclined at an angle α of about 45 ° to the plane E hammer surface 15 and the plane E at an angle β of about 135 ° inclined anvil surface 16 together.

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

Claims (5)

1. Percussion drilling machine having a tool shaft (2), at the free end of which a drill chuck is arranged, and having a rotary percussion mechanism having a drivable rotary percussion weight (3) having at least one hammer surface (15), and having an anvil (10) which is rotatable together with the rotary percussion weight (3) about a common rotation axis (13), is operatively connected to the tool shaft (2) so as to transmit torque and has at least one anvil surface (16) on which the hammer surface (15) is arranged so as to act in a percussive manner in the circumferential direction, wherein the tool shaft (2) is mounted in an axially adjustable manner, and wherein the anvil surface (16) and/or the hammer surface (15) are/is oriented and/or formed such that an impact of the hammer surface (15) on the anvil surface (16) results, in addition to a rotary impulse on the tool shaft (2) in the circumferential direction, in an adjustment of the tool shaft (2) in the axial direction (17), characterized in that the hammer surface (15) is inclined at an angle (α) of between 35° and 55°, preferably around 45°, to a plane (E) extending orthogonally to the rotation axis (13).
2. Percussion drilling machine according to Claim 1, characterized in that the rotary percussion mechanism (1) is provided with an adjusting mechanism having a restoring spring (9), said adjusting mechanism being formed to bring about a combined relative movement in the axial and in the circumferential direction and consequently the percussive action of the hammer surface (15) on the anvil surface (16) in the circumferential direction in the event of an increased torque requirement of the tool shaft (2) loaded by the restoring spring (9) between the rotary percussion weight (3) and the anvil (10).
3. Percussion drilling machine according to one of the preceding claims, characterized in that the anvil (10) has a plurality of anvil surfaces (16) that are inclined in the same direction and/or the rotary percussion weight (3) has a plurality of hammer surfaces (15) that are inclined in the same direction.
4. Percussion drilling machine according to one of the preceding claims, characterized in that the anvil (10) has at least two anvil surfaces (16) that are inclined in opposite directions to one another and/or the rotary percussion weight (3) has at least two hammer surfaces (15) that are inclined in opposite directions to one another.
5. Percussion drilling machine according to one of the preceding claims, characterized in that the tool shaft (2) is spring-loaded by a spring in the direction of a camshaft (18).

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