DE20217172U1 - Balancer for rotary tool holder in drill or mill has flange with radially outwardly extending bores to receive compensating weights - Google Patents

Abstract

The balancer for a rotary drill has a main body (1) to receive a bit (2) for rotation about a longitudinal axis (a). The tool holder has a flange with radially outwardly extending bores (3) to receive balance weights formed by hollow casings (4) clamped (5) on the recesses. The bores and weights can be threaded.

Description

Applicant ;

Mirko Flam

Burren Way 5

D - 72636 Tischardt Balancing element

The present invention relates to a balancing element for a rotating tool holder.

Drills or milling cutters, for example, are held on or in rotating tool holders. It is important, particularly at high speeds, that the tool holder with the tool clamped or otherwise attached to it is precisely balanced when rotating around the longitudinal axis.

This is necessary, for example, to prevent the tool holder bearings from becoming worn out and to enable the required accuracy when machining a workpiece.

To balance the tool holder, it is necessary

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It is known to attach balancing weights to the tool holder. This can be done, for example, by providing recesses on or in the tool holder that point essentially radially outwards and are aligned perpendicular to the longitudinal or rotational axis of the tool holder.

A so-called balancing weight can be inserted into these recesses and the depth at which the balancing weight is inserted into the tool holder can be regulated, for example via a thread provided in the recess, in order to balance the tool holder in this way.

However, it has proven to be disadvantageous that these balancing weights, which are designed in the form of a threaded pin, are not protected against automatic loosening, which cannot be ruled out, particularly under heavy loads and due to the vibrations of the tool holder that occur during normal operation.

This creates the possibility that the threaded pins may automatically loosen from their preselected position and, in extreme cases, may even pose a danger to the user during operation of the tool holder if the threaded pins become loose at high rotation speeds.

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Based on this state of the art, the invention has set itself the task of designing a balancing weight in such a way that automatic loosening is avoided.

According to the invention, this object is achieved by the features of claim 1. Advantageous embodiments of the invention emerge from the subclaims.

The core idea of the invention is that the balancing element is designed as a sleeve-shaped body, whereby this sleeve can in turn be secured in the recess via a further clamping element. Within the scope of the invention, the sleeve can be clamped in the recess in a variety of ways, e.g. by widening the sleeve as described below or by securing the sleeve in the axial direction in the recess in another way that can be carried out by a person skilled in the art. It is also conceivable that the sleeve-shaped body is secured in the recess in the tool holder with a pin-like device which in turn extends perpendicular to the longitudinal extension of the recess.

In a simple manner, the recess is designed as a threaded hole, whereby the threaded hole can either have a constant diameter over its entire depth or a variable one, whereby preferably the

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The diameter of the recess decreases with increasing depth, i.e. in the direction of the rotation axis of the tool holder.

To insert the sleeve-shaped balancing element, it is provided with an external thread that corresponds to the thread of the recess in order to be screwed into the threaded hole at the desired depth in order to achieve the desired balancing.

To clamp the balancing element, it has an internal thread into which the clamping element, which is provided with a corresponding external thread, can be screwed.
As described above for the recess, the internal thread of the sleeve can also be designed with either a constant or variable diameter.

The sleeve can be secured in the recess in a simple manner by allowing the sleeve to be expanded. This can be achieved, for example, by providing the sleeve with a slot running in the axial direction over its entire length or over a section of its longitudinal extension and by designing the clamping element in the form of a cone which expands the sleeve depending on the screw-in depth of the cone.

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For this purpose, the clamping element is designed in a simple manner as a threaded pin, which can also be conical in particular. This makes it easy to screw it into the sleeve and to fix it in the recess.

For this purpose, the clamping element is provided with means for actuation using an Allen key, a screwdriver or the like.

To ensure the tool holder is precisely balanced, the sleeve is also provided with means for being positioned at the desired depth in the recess. These means can be, for example, slot-like recesses in the sleeve into which a suitably designed tool can be inserted in order to screw the sleeve into the recess at the desired depth.

Preferably, 3, 4, 6 or 8 recesses are provided on the tool holder, distributed equidistantly around its circumference, in order to be able to carry out balancing as precisely as possible.

Further details, features and advantages of the invention can be found in the following description, in which the invention is presented in more detail with the aid of drawings.

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Fig. 1: the schematic structure of a

tool holder,
5

Fig. 2: a sleeve with clamping element, and

Fig. 3: a sleeve inserted into a recess.

The embodiment shown in Figure 1 is a tool holder which essentially consists of a base body 1. The tool holder rotates about a longitudinal axis a. A tool 2, e.g. a drill or milling cutter, can be inserted into the tool holder and secured in the base body 1 using means known to those skilled in the art but not shown here. Due to the rotation about the longitudinal axis a, it is necessary for the base body 1 with a tool 2 inserted therein to be balanced in order to avoid damage to the bearings of the tool holder on the one hand and to achieve the required accuracy when machining a workpiece with the tool 2 inserted on the other.

For this purpose, recesses 3 pointing radially outwards are provided in the base body 1 and are aligned essentially perpendicular to the axis of rotation a.

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The number of recesses 3 can be selected as desired, but in particular 3, 4, 6 or 8 recesses are distributed equidistantly over the circumference of the base body 1 in order to enable the balancing of the tool holder.

Balancing elements 4 can be inserted into the recesses 3. For this purpose, the recess 3 preferably has an internal thread 3a with an external thread 4b provided accordingly on the balancing element 4 in order to arrange the balancing element 4 at any depth in the recess 3.

This can be done, as shown in Figure 2, by the balancing element 4 being designed in the form of a sleeve, with slot-like recesses 6 being provided on the sleeve, into which a correspondingly designed tool 7 can be brought into engagement. Corresponding projections 8 are formed on this tool 7. Using the tool 7, the balancing element 4 in the form of a sleeve can be screwed into a threaded hole at the desired depth.

To fix the balancing element 4, this is provided with an internal thread 4a into which the clamping element 5 in the form of a threaded pin can be screwed. For this purpose, the clamping element 5 has an external thread 5b, which

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Internal thread 4a of the balancing element 4 corresponds. The balancing element 4 is preferably designed to be expandable in order to be fixed in the recess 3 by the balancing element 5. This can be achieved, for example, by a slot or gap provided in the axial direction in the sleeve.

To operate the clamping element 5, this can also be operated using another tool. This can be done, for example, using a hexagonal hole 9 in the clamping element 5. As can be seen in Figure 3, an Allen key 10 or the like can be inserted into this hexagonal hole 9. This turns the threaded pin 5 inside the sleeve 4 in order to secure the sleeve 4 in the recess 3.

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- 9 -Reference list

1 base body

2 Tools

3 Recess

3a internal thread in3

4 Balancing element

4a Internal thread in 4

4b External thread on

5 clamping element

5b External thread on

6 slot in 4

7 Tool for operating

8 lead on 7

9 Hexagon hole in

10 hexagon keys

a Longitudinal axis of 1

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Claims (9)

1. Balancing element for a rotating tool holder with a base body ( 1 ), wherein a tool ( 2 ) can be fastened to the base body ( 1 ), the base body ( 1 ) can be rotated about a longitudinal axis (a) and the base body ( 1 ) has recesses ( 3 ) pointing radially outwards and arranged essentially perpendicular to its longitudinal axis (a), into which balancing elements ( 4 ) can be inserted to compensate for imbalances, characterized in that - the balancing element ( 4 ) is a sleeve, - the sleeve can be fixed in the recess ( 3 ) with a clamping element ( 5 ). 2. Balancing element according to claim 1, characterized in that the recess ( 3 ) is a threaded bore. 3. Balancing element according to claim 1 or 2, characterized in that the sleeve ( 4 ) has an external thread ( 4b ). 4. Balancing element according to one of the preceding claims, characterized in that the sleeve ( 4 ) has an internal thread ( 4a ). 5. Balancing element according to one of the preceding claims, characterized in that the sleeve ( 4 ) is expandable. 6. Balancing element according to one of the preceding claims, characterized in that the clamping element ( 5 ) is a threaded pin. 7. Balancing element according to one of the preceding claims, characterized in that the clamping element ( 5 ) can be actuated with an Allen key ( 10 ) or the like. 8. Balancing element according to one of the preceding claims, characterized in that the balancing element ( 4 ) is provided with means for adjusting the depth of the balancing element ( 4 ) in the recess ( 3 ). 9. Balancing element according to one of the preceding claims, characterized in that 3, 4, 6 or 8 recesses ( 3 ) are provided on the base body ( 1 ).