The present invention relates to a tool holding arrangement comprising a tool holding device, a freely rotatable outer sleeve and a rotatable shaft which is at least connectable to a tool driving power source. The tool holding device comprises a first torque-transmitting means and an outer thread and the shaft comprises a second torque-transmitting means. The outer sleeve comprises an inner thread. The torque-transmitting means are arranged to engage each other and the threads are arranged to engage each other when the tool holding device is connected to the shaft.

BACKGROUND ART

Construction machines are for example used when renovating, reconstructing and extending buildings. Drill motors with annular core bits are normally used for drilling holes, for example for piping in floors and walls of buildings. Tool holders are used for connecting a tool, such as a drill, to the core bit, where the tool is attached to the tool holder; for example by means of welding.

The connection between a core bit and a tool holder is often made by means of threads, where the tool holder is screwed to the core bit. However, such an arrangement has disadvantages such as jamming of the threads. Therefore, other types of connections between a core bit and a tool holder have been proposed.

In US 2004/0154838 a tool holder is arranged for mounting to a core bit by means of coaxially arranged corresponding guide members, splines and conical surfaces which engage each other. In order to secure the mounting, a threaded flange on the core bit is screwed to corresponding threads on the tool holder.

However, there is still a need for a less complicated and easily managed tool holding arrangement for mounting and securing a tool holder to a core bit. SUMMARY

One object of the invention is to provide a tool holding arrangement comprising a tool holding device, a freely rotatable outer sleeve and a rotatable shaft which is at least connectable to a tool driving power source. The tool holding device comprises a first torque-transmitting means and an outer thread, and the shaft comprises a second torque-transmitting means. The outer sleeve comprises an inner thread. The torque-transmitting means are arranged to engage each other and the threads are arranged to engage each other when the tool holding device is connected to the shaft.

The shaft comprises a first circumferential shaft flange with a first diameter and a second circumferential shaft flange with a second diameter. The shaft flanges are separated by a circumferential shaft groove with a third diameter. The outer sleeve has a minimum sleeve inner diameter which exceeds at least one of the first diameter and the second diameter. The tool holding arrangement further comprises a first sleeve flange part and a second sleeve flange part, where the sleeve flange parts are mountable to, and dismountable from, the outer sleeve. When the sleeve flange parts are mounted to the outer sleeve, they have at least one maximum flange part inner diameter that falls below both the first diameter and the second diameter, but exceeds the third diameter.

According to an example, when the tool holding device is to be connected to the shaft, the shaft is positioned to run through the outer sleeve and the sleeve flange parts are mounted to the outer sleeve such that the sleeve flange parts are positioned between the first circumferential shaft flange and the second circumferential shaft flange. This prevents the outer sleeve from coming off the shaft.

According to another example, the tool holding arrangement further comprises a first spring washer and a second spring washer. The spring washers are sandwiched between the corresponding sleeve flange parts and the outer sleeve when the sleeve flange parts are mounted to the outer sleeve. According to another example, when the tool holding device is connected and axially locked to the shaft, the threads are engaged such that the spring washers abuts a first side of the first circumferential shaft flange. In the above case, each spring washer may comprise at least one protrusion, each protrusion being arranged to resiliently engage a plurality of corresponding recesses arranged along the first side of the first circumferential shaft flange. This arrangement provides a click-lock function with distinct locking positions when the protrusions engage corresponding recesses.

Other examples are disclosed in the dependent claims.

Many advantages are provided by means of the present invention. Mainly, a less complicated and easily managed tool holding arrangement for mounting and securing a tool holder to a core bit is provided..

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be described in more detail with reference to preferred embodiments and the appended drawings, where: shows a perspective view of an assembled tool holding arrangement; shows a perspective view of a partly disassembled tool holding arrangement; shows an exploded perspective view of the tool holding arrangement; shows a perspective view of a rotatable shaft; shows a perspective view of spring washers; shows a first perspective view of a tool holding device;

Figure 7 shows a second perspective view of the tool holding device; Figure 8 shows a first perspective view of a rotatable outer sleeve;

Figure 9 shows a second perspective view of the rotatable outer sleeve; Figure 10 shows a view of mounted shaft flanges; and

Figure 1 1 shows a first perspective view of an alternative rotatable shaft. DETAILED DESCRIPTION

With reference to Figure 1 and Figure 2, showing detailed perspective views of a tool holding arrangement 1 , the tool holding arrangement 1 comprises a tool holding device 2, a freely rotatable outer sleeve 3 and a rotatable shaft 4 which here is shown connected to an electric tool driver 5. The electric tool driver 5, in Figure 1 and Figure 2 only shown partially, is of a conventional kind and will not be further discussed here.

With reference also to Figure 6 and Figure 7, showing detailed perspective views of the tool holding device 2, the tool holding device 2 is arranged to be fastened to a suitable tool such as a drill, not shown, by means of, for example, welding to a surface 37 facing away from the electric tool driver 5 when mounted. The tool holding device 2 comprises a first torque-transmitting means 6 in the form of an octagonal through hole 6 running through the tool holding device 2. The tool holding device 2 further comprises an outer thread 7, in this example shown as a trapezoidal thread.

With reference instead also to Figure 4, showing a detailed perspective view of the shaft 4, the shaft 4 comprises a second torque-transmitting means 8 in the form of an octagonal rod 8, arranged to fit in the octagonal through hole 6 of the tool holding device 2. The torque-transmitting means 6, 8 are arranged to engage each other when the tool holding device 2 is connected to the shaft 4. Apertures 38; 39a, 39b, 39c for handling water and dust are arranged in a conventional manner. With reference also to Figure 8 and Figure 9, showing detailed perspective views of the outer sleeve 3, the outer sleeve 3 comprises an inner thread 9, arranged to engage the outer thread 7 of the tool holding device 2 when the tool holding device 2 is connected to the shaft 4. The outer sleeve 3 comprises an outer grip surface 40 that has a structure that allows it to be relatively easily turned by hand, here shown having longitudinally extending ribs. The outer sleeve 3 has a first side 41 and a second side 42, the first side 41 facing away from the electric tool driver 5 when mounted and the second side 42 facing the electric tool driver 5 when mounted. The second side 42 comprises six screw receiving apertures 31 , 32, 33; 34, 35, 36, equipped with inner threads. The purpose of these apertures is explained later in the description.

According to the present invention, with reference to Figure 3 and Figure 4, the shaft 4 comprises a first circumferential shaft flange 10 with a first diameter Di and a second circumferential shaft flange 11 with a second diameter D ₂ , the shaft flanges 10, 11 being separated by a circumferential shaft groove 12 with a third diameter D ₃ . As shown in Figure 9, the outer sleeve 3 has a minimum sleeve inner diameter D _imin which exceeds at least one of the first diameter Di and the second diameter D ₂ .

As shown in Figure 2 and 3. the tool holding arrangement 1 further comprising a first sleeve flange part 13 and a second sleeve flange part 14, the sleeve flange parts 13, 14 being mountable to, and dismountable from, the outer sleeve 3. In this example the mounting is enabled by means of screws 18, 19, 20; 21 , 22, 23 arranged to run through corresponding apertures 24, 25, 26; 27, 28 29 in the sleeve flange parts 13, 14 and to be screwed into the corresponding screw receiving apertures 31 , 32, 33; 34, 35, 36 in the outer sleeve 3.

When mounted to the outer sleeve 3, as shown in Figure 10, the sleeve flange parts 13, 14 have at least one maximum flange part inner diameter Df _max that falls below both the first diameter Di and the second diameter D ₂ , but exceeds the third diameter D3.

In this way, the outer sleeve 3 may be thread onto the shaft and positioned such that when the sleeve flange parts 13, 14 are mounted to the outer sleeve 3, the sleeve flange parts 13, 14 become positioned between the first circumferential shaft flange 10 and the second circumferential shaft flange 11 , preventing the outer sleeve 3 from coming off the shaft 4. This enables an easy mounting and dismounting of the outer sleeve 3 from the shaft 4.

The outer sleeve 3 is mounted to the shaft 4 in the above manner when the tool holding device 2 is to be connected to the shaft 4. Now, it is possible to mount the tool holding device 2 to the shaft 4 by screwing the outer sleeve 3 such that its inner threads 9 engage the outer threads 7 of the tool holding device 2. Then the tool holding device 2 is connected and axially locked to the shaft 4.

In order to obtain an enhanced mounting of the outer sleeve 3 to the shaft 4, the tool holding arrangement 1 may alternatively further comprise a first spring washer 15 and a second spring washer 16. The spring washers 15, 16 are sandwiched between the corresponding sleeve flange parts 13, 14 and the outer sleeve 3 when the sleeve flange parts 13, 14 are mounted to the outer sleeve 3. In order to enable such a mounting, the spring washers 15, 16 comprises apertures 43, 44, 45; 46, 47, 48 through which said screws 18, 19, 20; 21 , 22, 23 may run through. When the tool holding device 2 is connected and axially locked to the shaft 4, the spring washers 15, 16 abuts a first side 17 of the first circumferential shaft flange 10.

According to an example of a certain type of spring washers, as shown in the detailed perspective view in Figure 5, each spring washer 15, 16 may comprise two protrusions 15a, 15b; 16a, 16b. Each protrusion 15a, 15b; 16a, 16b is in the form of a finger extending radially inwards when the spring washers 15, 16 are mounted. These protrusions 15a, 15b; 16a, 16b are arranged to resiliently engage a plurality of corresponding recesses 17a, 17b, 17c, 17d, 17e, only a limited number of these recesses shown in Figure 4, arranged along the first side 17 of the first circumferential shaft flange 10. The total number of recesses in this example is 8.

By means of these protrusions 15a, 15b; 16a, 16b engaging the recesses 17a, 17b, 17c, 17d, 17e when the outer sleeve 3 is screwn to the tool holding device 2, a locking function is obtained for the outer sleeve 3, preventing it from unscrewing when running the electric tool driver 5 with the tool mounted.

With reference to Figure 11 , some alternatives for the shaft are shown. Figure 11 shows many resemblances to the shaft of Figure 4, and for reasons of clarity in Figure 11 , mainly only the parts that differ are indicated in Figure 11 and discussed in the following. It is to be understood that the other details are more or less the same, or at least equivalent. In Figure 11 , a shaft 4' has a torque-transmitting means in the form of a hexagonal rod 8', where, at the end of the hexagonal rod 8' that is arranged to face the tool holding device 2, a cylindrical first extension 30 is positioned. This cylindrical extension 30 has a fourth diameter D ₄ that falls below the larges distance between two edges of the hexagonal rod 8' and facilitates the mounting of the tool holding device 2 to the shaft 4'. Furthermore, at the other end of the hexagonal rod 8', facing and abutting the first circumferential shaft flange 10', a cylindrical second extension 31 is positioned, the second extension 31 thus being positioned between the second torque-transmitting means 8, 8' and the first circumferential shaft flange 10'. The second extension 31 has a fifth diameter that is larger than the first extension 30 and is arranged for steering the tool holding device 2 into a rigid holding position by means of a corresponding cylindrical aperture in the tool holding device 2 (not shown).

The cylindrical first extension 30 may also be arranged for steering the tool holding device 2 into a rigid holding position by means of another corresponding cylindrical aperture in the tool holding device 2 (not shown).

Either one of these extensions 30, 31 may be omitted, and may also be used for any type of torque-transmitting means, not only the hexagonal rod 8' shown in this example. One or both of the extensions 30, 31 may instead have a conical shape, where the diameter increases towards the first circumferential shaft flange 10'.

The present invention is not limited to the above, but may vary freely within the scope of the appended claims. For example, the shaft may not be directly connected to the electric tool driver 5, but may constitute an intermediate part. Often the shaft of the electic tool driver has an end with an outer thread intended to be screwed into an inner thread of the tool, normally a drill bit. In this case the tool holding arrangement is in the form of an adapter, where the rotatabie shaft 4 is secured to the thread of the shaft of the electric tool driver and the tool holding device 2 is secured to the thread of the tool.

The electric tool driver 5 is generally in the form of a tool driving power source 5 which may be run by hand or by means of a motor that may be electric, hydraulic, air power, or of a combustion type.

The torque-transmitting means 6, 8 may have any suitable shape, for example in the form of corresponding splines or torques.

Other fastening means than the screws 18, 19, 20; 21 , 22, 23 is of course possible, and the number of such fastening means may vary.

The number of protrusions 15a, 15b; 16a, 16b may also vary. It is possible to have other types of resiliently engaging means, for example spring-loaded balls arranged in the shaft flanges 10, 11. In this case, no spring washers 15, 16 would be used.

The number of shaft flanges 10, 1 1 may vary, but there should be at least two in order to enable a relatively easy locking of the outer sleeve 3 to the shaft 4. Instead of shaft flanges 10, 11 , other traditional fastening means such as locking springs may be used.

The trapezoidal threads are only an example of suitable threads. Any type of suitable threads may be used, and it is desired that the threads are robust and durable.

The torque-transmitting means 6, 8 may have conical shape, having an increasing cross-sectional surface towards the first circumferential shaft flange 0'.

Circumferential recesses (not shown) may be made in the shaft 4, 4' at suitable positions, the recesses being adapted to receive sealings such as O-rings. An example is such a recess in the octagonal or hexagonal rod (8; 8'), both in a strait and conical shaped version. An other example is such a recess in the first or second extension (30; 31 ), both in a cylindrical or conical shaped version.

The number of recesses 17a, 17b, 17c, 17d, 17e arranged along the first side 17 of the first circumferential shaft flange 10 may vary, and is preferably an even multiple of the number of edges of the torque-transmitting means 6, 8. The number of recesses 17a, 17b, 17c, 17d, 17e may for example be double the number of engaging surfaces of the torque-transmitting means 6, 8, which for a hexagonal rod 8' results in twelve corresponding recesses and for an octagonal rod 8 results in sixteen corresponding recesses.

The spring washer may be made in any suitable material such as for example steel, copper or brass.