The tool holder may further comprise a lateral stiffness ring, the damping mass may comprise a groove, and the lateral stiffness ring may be seated in the groove and be in contact with the tubular element. The lateral stiffness ring may contribute to less than 30% of a total stiffness for supporting the damping mass.

According to a further aspect, there is provided a tool assembly comprising an end effector and a tool holder, having a damping mass that is balanced prior to assembly of the damping mass into the tubular element, according to the present disclosure.

Any tool assembly according to the present disclosure may be either stationary or rotated when machining a workpiece. Any tool holder or any tool assembly according to the present disclosure may be modular. The modularity may for example be used to attach different types of end effectors and/or different types of back ends to the tool holder. Due to the ability to mount different types of back ends to the tool holder, the tool holder can easily be adapted to fit a particular support, such as a machine spindle or a tool magazine. Alternatively, or in addition, the modularity may be used to modify the length and/or diameter of the tool holder, e.g. with the same damping mass. Due to the modularity, supply chain stocks of components to the tool holder or the tool assembly can be reduced.

According to one example, there is provided a kit of parts comprising a tool holder according to the present disclosure, a first back end and a second back end, wherein each of the first back end and the second back end is detachably connectable to the tool holder, and wherein the first back end is connectable to a first support of a first size and the second back end is connectable to a second support of a second size, different from the first size.

According to a further example, there is provided a kit of parts comprising a tool holder according to the present disclosure, a first end effector and a second end effector, wherein each of the first end effector and the second end effector is detachably connectable to the tool holder, and wherein the first end effector is of a first type and the second end effector is of a second type, different from the first type.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details, advantages and aspects of the present disclosure will become apparent from the following embodiments taken in conjunction with the drawings, wherein:

FIG. 1: schematically represents a perspective view of a tool assembly comprising a tool holder and an end effector;

FIG. 2: schematically represents a cross-sectional side view of the machine tool;

FIG. 3: schematically represents a partial cross-sectional perspective view of the tool assembly;

FIG. 4: schematically represents a partly exploded cross-sectional side view of the tool assembly;

FIG. 5:

schematically represents a perspective view of an adapter of the tool holder;

FIG. 6: schematically represents a perspective view of a further example of a damping mass for the tool holder;

FIG. 7: schematically represents a cross-sectional side view of a further example of a tool holder; and

FIG. 8: schematically represents a cross-sectional side view of a further example of a tool holder.

DETAILED DESCRIPTION

In the following, a tool holder having an adapter with an opening for receiving a damping mass, a tool assembly comprising such tool holder, a tool holder having an adapter integrated with a tubular element, a tool assembly comprising such tool holder, a tool holder having a damping mass that is balanced prior to assembly of the damping mass into a tubular element, and a tool assembly comprising such tool holder, will be described. The same or similar reference numerals will be used to denote the same or similar structural features.

FIG. 1 schematically represents a perspective view of a tool assembly 10, here exemplified as a milling tool. The tool assembly 10 comprises a tool holder 12 and an end effector 14, here exemplified as a milling head, connected to the tool holder 12. FIG. 1 further shows a central axis 16 of the tool assembly 10.

The end effector 14 comprises a plurality of cutting teeth 18 for machining a workpiece (not shown). The end effector 14 of this example comprises four cutting teeth 18.

As shown in FIG. 1, the tool holder 12 comprises a tubular element 20 and an adapter 22. Each of the tubular element 20 and the adapter 22 is concentric with the central axis 16. The end effector 14 is secured to the tubular element 20 by means of the adapter 22.

The tool holder 12 further comprises a back end 24. The back end 24 can be connected to a support (not shown) for supporting the tool assembly 10. During machining of a workpiece, there is a relative rotation between the tool assembly 10 and the workpiece about the central axis 16. That is, either the tool assembly 10 rotates and the workpiece is stationary, or vice versa.

FIG. 2 schematically represents a cross-sectional side view of the tool assembly 10. FIG. 3 schematically represents a partial cross-sectional perspective view of the tool assembly 10. With collective reference to FIGS. 2 and 3, the tubular element 20 comprises a cavity 26. The tubular element 20 is cylindrical.

The tool assembly 10 further comprises a damping mass 28. The damping mass 28 is arranged inside the cavity 26. During machining operations by the tool assembly 10, vibrations cause the damping mass 28 to move radially with respect to the central axis 16 and relative to the tubular element 20. The vibrations also cause the damping mass 28 to move axially with respect to the central axis 16.

The damping mass 28 is cylindrical and comprises two end surfaces. The damping mass 28 comprises a central mass cavity 30. The damping mass 28 may be made of high-density materials, such as tungsten alloys.

The adapter 22 comprises a front part 32 and a rear part 34. The front part 32 is positioned closer to the end effector 14 and the rear part 34 is positioned closer to the back end 24.

The rear part 34 comprises an external thread 36. The tubular element 20 comprises an internal thread 38. The external thread 36 threadingly engages the internal thread 38 to thereby form a threaded engagement. In this way, the adapter 22 is fixed to the tubular element 20. The external thread 36 may handed such that the cutting force tightens the threaded engagement. The threaded engagement can thereby provide a higher fixing force than prior art solutions employing pins for securing an adapter to a tubular element. Due to the pitch sections of the threaded engagement, the surface area where shear stress is distributed is higher than such prior art solutions. Glue may also be introduced to the threaded engagement to improve fatigue resistance of the threaded engagement.

The rear part 34 comprises an opening 40. The damping mass 28 is partly received in the opening 40. This enables a distance d between a front end of the damping mass 28 and a front end of the adapter 22 to be reduced. This improves the surface finish capability of the tool assembly 10.

A radial clearance is established between an outer diameter of the damping mass 28 and an inner diameter of the opening 40. The opening 40 is circular and concentric with the central axis 16.

As shown in FIGS. 2 and 3, a rear end of the opening 40 is aligned with a rear end of the external thread 36. A front end of the external thread 36 is positioned in front of a front end of the opening 40. The opening 40 is thus arranged radially inside the external thread 36. Moreover, the opening 40 and the external thread 36 are overlapping along the central axis 16.

The front part 32 comprises an internal thread (not denoted). The internal thread of the front part 32 can be threadingly engaged by a bolt (not shown) in order to secure the end effector 14 to the adapter 22.

The tool holder 12 further comprises a front elastic element 42. The front elastic element 42 is arranged to damp vibrations of the damping mass 28, in particular radial vibration movements. The front elastic element 42 is arranged between the adapter 22 and the damping mass 28. The front elastic element 42 comprises a front surface 44 and a rear surface 46. The front surface 44 is rigidly connected to the front surface of the damping mass 28.

The rear surface 46 is rigidly connected to the rear surface of the front plate 48.

Each of the front surface 44 and the rear surface 46 is perpendicular to the central axis 16. The perpendicular orientation of the front surface 44 and the rear surface 46 to the central axis 16 causes the front elastic element 42 to mainly experience shear stresses. This enables the front elastic element 42 to be made very thin, for example only 1 mm. Since the front elastic element 42 can be made thin, the damping mass 28 can be moved even more close to the end effector 14.

The rear surface 46 directly contacts the front end surface of the damping mass 28. The front elastic element 42 is concentric with the central axis 16.

The tool holder 12 of this example further comprises a front plate 48, here exemplified as a circular thermal insulation plate. The front plate 48 is in contact with the adapter 22. The front surface 44 directly contacts a rear end surface of the front plate 48. The front plate 48 is concentric with the central axis 16.

The rear part 34 of this example further comprises an adapter aperture 50. The front plate 48 is received in the adapter aperture 50 by means of an engineering fit. This improves alignment of the damping mass 28 with the central axis 16.

The front plate 48 may be locked to the adapter 22 with glue, such as instant glue. Alternatively, the front plate 48 may be rotatable relative to the adapter 22. In this case, grease may be applied between the front plate 48 and the adapter aperture 50. The grease enables an improved transmission of vibration energy in comparison to air.

In this example, the front elastic element 42 is arranged between the front plate 48 and the damping mass 28. The front surface 44 directly contacts the front plate 48.

The tool holder 12 of this example further comprises a rear plate 52 and a tail lock 54. The rear plate 52 is arranged between the damping mass 28 and the tail lock 54. The rear plate 52 has the same configuration as the front plate 48. The rear plate 52 is in contact with the tail lock 54.

The tail lock 54 comprises a tail lock aperture 56. The rear plate 52 is received in the tail lock aperture 56. This improves alignment of the damping mass 28 with the central axis 16.

The tool holder 12 of this example further comprises a rear elastic element 58. The rear elastic element 58 is arranged between the damping mass 28 and the tail lock 54. In this example, the rear elastic element 58 is arranged between the damping mass 28 and the rear plate 52. The rear elastic element 58 may have the same configuration as the front elastic element 42. Alternatively, the rear elastic element 58 may differ in size and material comparing to the front elastic element 42. Each elastic element 42, 58 may be a viscoelastic element.

Each elastic element 42, 58 is self-adhesive. The front elastic element 42 is adhered to the front plate 48 and to the damping mass 28. The rear elastic element 58 is adhered to the damping mass 28 and to the rear plate 52.

The tool holder 12 further comprises a fluid pipe 60. The fluid pipe 60 passes through the mass cavity 30. The fluid pipe 60 also passes through a through-hole in each of the plates 48, 52 and in each of the elastic elements 42, 58. The fluid pipe 60 is threadingly connected to the adapter 22 and threadingly connected to the tail lock 54. The fluid pipe 60 is thereby fixed to each of the adapter 22 and the tail lock 54. Sealing glue is also provided to these thread connections. The fluid pipe 60 is configured to convey coolant towards the end effector 14. The fluid pipe 60 is concentric with the central axis 16.

In case the adapter aperture 50 and the tail lock aperture 56 are omitted, each of the front plate 48 and the rear plate 52 may be fitted to the fluid pipe 60 by means of an engineering fit. Also in this way, the damping mass 28 can be aligned with the central axis 16.

The adapter 22 further comprises coolant channels 62. The coolant channels 62 are arranged to provide high pressure coolant from the fluid pipe 60 to the end effector 14. In this example, the coolant channels 62 each extends parallel with the central axis 16.

The damping mass 28 comprises a groove 64. The groove 64 extends around the circumference of the damping mass 28 and is concentric with the central axis 16. The groove 64 of this example is centered on the damping mass 28 along the central axis