Tool holding device for hammer drill or chisel hammer

Abstract

The invention relates to a tool holding device for a hammer drill or chisel hammer, comprising a tubular tool holding body (1) for a tool (2), on the end stop of which a coaxially arranged strike ram (3) of a hammer mechanism is arranged, wherein the tubular tool holding body (1) interacts with a locking mechanism (4) which radially penetrates a wall region of the tool holding body (1), wherein a latching element (6) of the locking mechanism (4), which latching element is arranged along the circumference of the tool holding body (1) and is held in a locked position by a spring (5), can be moved into an unlocked position by means of an outer adjusting sleeve (7) by means of an axial displacement in the direction against the spring effect in order to remove the inserted tool (2), wherein a circumferential groove (8) for actively fixing an elastomeric ring element (10) is provided on the housing surface of the tool holding body (1), which elastomeric ring element in the locking position rests on the front face of a corresponding locking ring (11) for actively holding the latch element (6) in the locking position.

Description

Technical Field

[0001] The invention relates to a tool holding device for a hammer drill or a chisel hammer, the tool holding device comprising a tubular tool holding body for a tool, at the end stop of which a coaxially arranged striker of a hammer mechanism is arranged at the rear, wherein the tubular tool holding body interacts with a locking mechanism which radially penetrates a wall area of ​​the tool holding body, wherein a latching element or the like of the locking mechanism which is arranged along the circumference of the tool holding body and is held in a locked position by a spring can be moved into an unlocked position by an axial displacement counteracting the spring effect by means of an external adjustment sleeve in order to remove an inserted tool.

[0002] The field of application of the invention extends primarily to hand-held hammer drills or chisel hammers, which are provided with an electric motor drive. Such electric hand tools generate a linear alternating working movement via a mechanical hammer mechanism, i.e. a reciprocating movement for an impact tool, which in the case of a chisel hammer is designed as a mortise chisel and in the case of a hammer drill is designed as an impact drill, for working preferably on mineral materials such as stone, concrete, etc. In general, due to the interaction with the workpiece and the operator's arm system and the internal mass and stiffness distribution, the electric hand tools capable of driving the tool show complex vibration behavior, which must be suppressed as much as possible.

[0003] In the context of the electric hand tools of interest here, tool holders are primarily used to secure and guide drilling or chiseling tools in these machines. The tool holder transmits the torque to the tool, ensures the transmission of the blow pulses from the hammer mechanism to the workpiece by allowing limited axial movement, and prevents the tool from accidentally falling out of the machine. The tool holder according to the invention is exposed to particularly large dynamic vibration loads, in particular by high-frequency hammer mechanism pulses. Background Art

[0004] DE 100 43 416 A1 discloses a universal tool holding device. It consists essentially of a tubular tool holding body for a tool, on which a hammer mechanism acts backwards. A locking mechanism for the tool with a corresponding holding groove comprises at least one locking element, which is pressed down by a locking sleeve to ensure a positive-locking connection. Each locking element is held in a locked position via a compression spring, and by means of an external adjustment sleeve the locking mechanism can be moved by axial displacement into an unlocked position, in which the inserted tool can be removed again from the tubular tool holding body. An annular damping element made of an elastomeric material and arranged on the front side of the locking sleeve serves for vibration damping in the region of the locking mechanism.

[0005] The situation in which the tool is accelerated by the striking pulse of the hammer mechanism, but this impact energy cannot be transferred to the workpiece is called the so-called tool idle strike. Therefore, this type of tool idle strike occurs when the tool does not act on the surface of the workpiece. In the case of a tool idle strike, if the locking mechanism fails, the inserted tool may leave the machine at high speed. Locking elements are provided to prevent the tool from falling out of the tool holding device, and these locking elements are generally arranged in axially aligned elongated holes of the tubular tool holding body and are retained on the inner diameter of the locking ring in the radial direction. In the axial direction, the locking element is pressed into the locking ring against the stop by means of a spring force. As a result, the locking element is sunk into the closed groove at the insertion end of the tool, absorbs the movement energy of the tool at the groove end, and transfers the movement energy to the tubular tool holding body via the locking ring.

[0006] The energy of such tool idling blows is absorbed by a damping element integrated into the locking mechanism. To this end, the damping element is prestressed between a locking ring and a stop disk, which is fixed to the tubular tool holder body by a clamping ring. The clamping ring also fixes all components mounted on the tubular tool holder.

[0007] Vibrations of the hammer mechanism during normal operation and impact pulses during idling strikes of the tool continuously cause relative displacements of the retaining ring in its retaining groove on the base body, which, under the additional effect of abrasive concrete dust, can lead to wear of the retaining ring connection and ultimately to its failure.

[0008] This snap ring connection must be released during every repair-related disassembly of the tool holder. Since this can only be achieved by removing the prestressing of the damping element, a special tool is required for this, which must be fixed in the inner diameter of the tubular tool holder body. In the event that the tool holder body is worn and the tool insertion end is stuck or broken, disassembly is almost impossible.

[0009] DE 10 2005 000 097 A1 discloses a further tool holder for a hammer drill or a chisel hammer, which further tool holder also comprises radially displaceable locking bodies, here in the form of spherical elements. In the locked state, they interact with radially outwardly locking members, which are provided with locking surfaces which are configured to be damped and radially face the locking element. The damped locking surfaces can be made of an elastomer, thereby ensuring a damped contact with the locking mechanism even in the event of strong radial oscillations of the locking element. However, no axially acting damping member is provided in this prior art.

[0010] The tool holding device therefore requires several components for fixing and damping the tool, such as in particular a retaining ring, a stop element and a damping element.

[0011] The object of the present invention is to further improve a tool holding device of the generic type in such a way that effective vibration damping can be achieved with fewer components. Summary of the invention

[0012] This object is achieved by a tool holder for a hammer drill or a chisel according to the preamble of claim 1 in combination with its characterizing features. The following dependent claims describe advantageous developments of the invention. With regard to a hammer drill or a chisel having a tool holder according to the invention, reference is made to claim 10.

[0013] The present invention includes the following technical teaching, namely, a circumferential groove for directly actively fixing an elastomeric ring element is arranged on the outer shell surface of the tool holding body, and the elastomeric ring element directly abuts against the corresponding locking ring on the front side in the locking position to actively hold the latch element in the locking position.

[0014] In other words, according to the invention, a compact elastomeric ring element is created, which is inserted into a circumferential groove of corresponding size on a tubular tool holding body and replaces the previously required components (i.e., a retaining ring, a damping element and a stop disk). In the event of vibrations and shock pulses, a radially dominant force component is generated in the elastomeric ring element, which presses the elastomeric ring element into the groove bottom of the circumferential groove and thus prevents the elastomeric ring element from jumping out of the circumferential groove. The damping effect of the elastomeric ring element is mainly achieved by its deformation in the direction of this force component between the locking ring and the circumferential groove in the tool holding body. Due to the elastic active fit between the elastomeric ring element and the circumferential groove, no additional special tools are required to remove these components. This is because the elastomeric ring element can simply be pried out of the circumferential groove and removed from the tool holding body.

[0015] According to a further measure to improve the invention, it is provided that the elastomeric ring element is guided in the main axial direction of movement by at least one annular groove on the end face in the locking ring. Thus, there is a further annular positive fit between the locking ring and the elastomeric ring element. In the locked state of the tool holder, the elastomeric ring element is preferably radially prestressed by the locking ring between the annular groove and the circumferential groove of the tool holder body, in order to be able to compensate for tool idling strikes in particular.

[0016] The width of the circumferential groove is greater than its groove depth for properly mounting the elastomeric ring element in the circumferential groove of the tubular tool holding body, wherein the elastomeric ring element is prevented from jumping out by a radial positive fit.

[0017] The assembly of the elastomeric ring element can be achieved by pushing the elastomeric ring element onto the tool holding body until it engages in the circumferential groove. The disassembly is performed by prying the elastomeric element out of the circumferential groove of the tool holding body, which is achieved by at least one radially extending disassembly groove provided on the front face of the elastomeric ring element.

[0018] In order to give priority to the radial force component between the locking ring with the annular groove and the elastomeric ring element, and therefore to prevent the elastomeric ring element from jumping out of the circumferential groove of the tool holding body in the event of an idling impact of the tool, an at least partially formed axial gap is provided between the locking ring and the elastomeric ring element in the unloaded state.

[0019] The elastomeric ring element is preferably made of a hydrogenated NBR (nitrile rubber) material which is distinguished by a long service life, high temperature resistance and elasticity which is sufficient for the use according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Further measures that improve the invention are specified in the dependent claims or are explained in more detail below together with the description of preferred exemplary embodiments with reference to the attached drawings. In the drawings: Figure 1 shows a schematic longitudinal section of a tool holding device; Figure 2 Shown according to Figure 1 A cross section in section AA of the tool holding device; Figure 3 shows an enlarged fragmentary view of a longitudinal section of the tool holding device in the region of the locking mechanism; and Figure 4 A perspective view of the elastomeric ring element of the locking mechanism is shown. DETAILED DESCRIPTION

[0021] according to Figure 1 The tool holding device according to the invention for a hammer drill or a chisel hammer (not shown in detail here) consists of a tubular tool holding body 1. The grooved distal end region of a tool 2 can be inserted into the tubular tool holding body 1 and then locked. In the locked state, an impact hammer 3 of a hammer mechanism (not shown in detail here) acts on the tool 2, which is arranged coaxially behind the tool 2.

[0022] For locking, the tubular tool holding body 1 interacts with a locking mechanism 4 which radially penetrates the wall region of the tubular tool holding body. Its latching element 6 is arranged along the circumference of the tool holding body 1 and is held in the locked position by a spring 5, which can be moved into the unlocked position by means of an external adjustment sleeve 7 by an axial movement in the direction of the machine housing 9 in the direction opposing the spring effect in order to remove the inserted tool 2. The spring 5 is designed as a compression spring and acts on the latching element 6 via an annular pressing element 12.

[0023] A circumferential groove 8 is provided on the outer surface of the tool holding body 1 for the active fixing of the elastomeric ring element 10. In the locked position, the elastomeric ring element 10 rests axially on a corresponding locking ring 11. The locking ring 11 serves to hold the latching elements 6 in a locked position in which they engage in the grooved end region of the tool 2 in an actively locked manner.

[0024] according to Figure 2 In this exemplary locking mechanism, two latch elements 6, 6' arranged opposite to each other are used, and the elastomeric ring element 10 has a contoured surface.

[0025] like Figure 3 As can be seen in FIG. 1 , due to the tool idle impact pulse on the rear end of the tool 2 and due to the generally active fit, a force component is transmitted into the latching element 6, which is shown here by way of example. The locking element 6 transmits the impact pulse to the locking ring 11, which introduces the impact pulse into the elastomer ring element 10. Depending on the material, the impact pulse is damped by the elastomer ring element 10, wherein the locking ring 11 performs a corresponding axial damping movement together with the latching element 6. Thus, the tool idle impact pulse damped by the circumferential groove 8 acts on the tubular tool holding body 1 and thus on the tool holding device of the hammer drill or chisel hammer.

[0026] Furthermore, the locking ring 11 has a front annular groove 13 for guidance in the axial displacement direction, which annular groove 13 interacts in a positively locking manner with a corresponding formation of the elastomeric ring element 10 .

[0027] according to Figure 4 The elastomeric ring 10 is provided with a plurality of disassembly grooves 14a to 14c on the front side for prying the components out of the circumferential grooves (not shown here) on the tubular tool holding body.

[0028] The invention is not limited to the preferred exemplary embodiments described above. On the contrary, modifications thereof are also conceivable, which modifications are covered by the protection scope of the following claims. Thus, for example, it is also possible to use differently shaped locking elements (such as locking balls or locking rollers) instead of latching elements for locking.

[0029] List of Reference Numerals 1 Tool holding body 2 Tools 3 Strike hammer 4 Locking mechanism 5 Spring 6 Latch element 7 Adjustment sleeve 8 Circumferential grooves 9 Machine housing 10Elastomer ring element 11 Locking element 12 Pressing elements 13 Annular groove 14 Disassembly slot

Claims

1. A tool holding device for a hammer drill or chisel, the tool holding device comprising a tubular tool holding body (1) for a tool (2), a coaxially arranged striker (3) of a hammer mechanism being arranged at the end stop of the tubular tool holding body, wherein the tubular tool holding body (1) interacts with a locking mechanism (4) which radially penetrates a wall region of the tool holding body (1), wherein a latching element (6) of the locking mechanism (4) which is arranged along the circumference of the tool holding body (1) and is held in a locked position by a spring (5) can be moved into an unlocked position by means of an external adjustment sleeve (7) by an axial displacement in a direction counter to the spring effect in order to remove the inserted tool (2), It is characterized in that A circumferential groove (8) for actively fixing an elastomeric ring element (10) is arranged on the outer surface of the tool holding body (1), and the elastomeric ring element abuts against a corresponding locking ring (11) at the front in the locking position to actively hold the latching element (6) in the locking position.

2. The tool holding device according to claim 1, It is characterized in that The elastomeric ring element (10) is guided in a mainly axial direction of movement by at least one annular groove (13) on the front side in the locking ring (11).

3. The tool holding device according to claim 2, It is characterized in that In the locked state, the elastomeric ring element (10) is radially prestressed between the annular groove (13) and the circumferential groove (8) of the tool holding body (1) by means of the locking ring (11).

4. The tool holding device according to claim 1, It is characterized in that The groove width of the circumferential groove (8) is greater than the groove depth, wherein the elastomeric ring element (10) is prevented from jumping out by radial positive fit.

5. The tool holding device according to claim 1, It is characterized in that At least one disassembly groove (14) is arranged on the front side of the elastomeric ring element (10), and the at least one disassembly groove is used to pry the elastomeric ring element (10) out of the circumferential groove (8).

6. A tool holding device according to any one of the preceding claims, It is characterized in that In the unloaded state, when locked, there is at least partially an axial gap between the elastomeric ring element (10) and the locking element (11).

7. A tool holding device according to any one of the preceding claims, It is characterized in that The elastomeric ring element (10) is made of hydrogenated NBR elastomeric material.

8. A tool holding device according to any one of the preceding claims, It is characterized in that The spring (5) is designed as a compression spring and acts on the latching element (6) via an annular pressing element (12), which can be actuated in the opposite direction by the outer adjustment sleeve (7) for unlocking.

9. The tool holding device according to claim 8, It is characterized in that The annular pressing element (12) has a substantially L-shaped cross section.

10. A hammer drill or chisel hammer for machining mineral material, in particular concrete or rock, having a tool holder according to any of the preceding claims.

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