DE102018111039A1 - Device for rotary drive of a tool and spindle for it - Google Patents

Abstract

Spindle (27) for a device (1) for rotary drive of a tool (6), comprising at least:
- A static spindle part (2) rotatably connected to a drive unit (26) of the device (1) is connectable, and
- A rotatable spindle part (3) which is rotatably mounted relative to the static spindle part (2) on the static spindle part (2) and which has an interface (5) for a tool holder (4) for the tool (6), via the the tool holder (4) can be connected in a rotationally fixed manner to the rotatable spindle part (3), wherein the static spindle part (2) has an outer coil (7), and the rotatable spindle part (3) has an inner coil (8), and wherein the outer coil (7 ) and the inner coil (8) for non-contact transmission of electrical energy from the static spindle part (2) via the outer coil (7) and the inner coil (8) on the rotatable spindle part (3) are arranged one inside the other.

Description

The invention relates to a device for rotational drive of a tool and a spindle for it.

When machining, for example, with a milling cutter, it is desirable to apply a tool such as a milling head with ultrasound. As a result, the removal of material by the milling head can be considerably increased, in particular in the case of particularly hard materials, and thus a machining speed can be increased.

For ultrasonic generation, it is regularly required to transfer electrical energy from a fixed part to a rotating part of a machine. To avoid friction losses and wear this is done in known approaches contactlessly via inductive coupling of coils. However, such transmission is possible according to the prior art only at relatively low speeds. Also, the transmission of electrical energy is often inefficient.

An inductive energy transfer can be realized between a coil and a (vibrating) tool holder. Such a concept has the disadvantage that each tool holder (eg a tool magazine of a highly automated production plant) has to be equipped with a corresponding coil, which leads to a very extensive adaptation of a multiplicity of different tool holders. In addition, the additional coil parts complicate the production of tool holders with a very good concentricity. In addition, an application of such systems in the high speed range requires special materials, since there are mechanical limits to the use of ferrite cores.

On this basis, it is an object of the present invention to solve the technical problems described in connection with the prior art or at least reduce. In particular, a device for the rotational drive of a tool, and a spindle for which electrical energy can be transmitted particularly efficiently from a stationary to a rotating part of the device and which are also suitable for particularly high rotational speeds are to be presented.

This object is achieved with a spindle and a device according to the features of the independent claims. Further advantageous embodiments of the spindle are specified in the respective dependent claims. The features listed individually in the claims can be combined with each other in any technologically meaningful manner and can be supplemented by explanatory facts from the description, with further embodiments of the invention being shown.

• - einen statischen Spindelteil, der drehfest mit einer Antriebseinheit der Vorrichtung verbindbar ist, und
• - einen rotierbaren Spindelteil, der relativ zu dem statischen Spindelteil drehbar an dem statischen Spindelteil gelagert ist und der eine Schnittstelle für einen Werkzeughalter für das Werkzeug aufweist, über die der Werkzeughalter drehfest mit dem rotierbaren Spindelteil verbindbar ist,

wobei der statische Spindelteil eine Außenspule aufweist, und der rotierbare Spindelteil eine Innenspule aufweist, und wobei des Weiteren die Außenspule und die Innenspule für eine berührungslose Übertragung elektrischer Energie von dem statischen Spindelteil über die Außenspule und die Innenspule auf den rotierbaren Spindelteil (insbesondere verschachtelt) ineinander angeordnet sind.For this purpose, a spindle contributes to a device for rotatably driving a tool, which comprises at least the following:

• - A static spindle part which is rotatably connected to a drive unit of the device, and
• a rotatable spindle part, which is mounted rotatably relative to the static spindle part on the static spindle part and which has an interface for a tool holder for the tool, via which the tool holder can be connected in a rotationally fixed manner to the rotatable spindle part,

wherein the static spindle part has an outer coil, and the rotatable spindle part has an inner coil, and further wherein the outer coil and the inner coil for non-contact transmission of electrical energy from the static spindle part on the outer coil and the inner coil on the rotatable spindle part (in particular nested) into each other are arranged.

The described spindle or the device can in particular be designed and set up for machining, for example in the manner of milling. For this purpose, a corresponding tool can be attached to the device. The tool may be, for example, a milling head. Alternatively or additionally, it is also possible that the described device is intended for drilling and set up. In that case the tool is a drill. Preferably, the tool can be detachably connected to the spindle so that the tool can be replaced by a user. Thus, the device described can be determined and set up in particular both for milling and for drilling.

The tool can be driven in rotation with the device. This means in particular that the tool is rotated by the device about an axis of the tool, which coincides with the axis of rotation of the device.

The tool can be connected via the tool holder with the device described and in particular with the rotatable spindle part. The tool holder, like the tool and the drive unit, is not part of the spindle. Rather, the rotating spindle part has the interface via which the tool holder can be connected to the rotatable spindle part. The interface may, for example, be a standardized interface of the HSK, SK or BT standard. Other deviating from the norm solutions are also conceivable. The tool holder can preferably be connected to the rotatable spindle part via the interface in such a way that a user can exchange the tool holder. For example, for different types of tool, the user can connect different tool holders to the rotatable spindle part.

The spindle is preferably designed such that the spindle can be connected to the drive unit with a first end face of the spindle. The interface is preferably provided on a second end face of the spindle opposite the first end face.

The tool can be connected to the rotatable spindle part via the tool holder. In particular, the tool can be releasably connected to the tool holder so that the tool can be replaced by a user. In operation, the tool is rotatably connected to the tool holder.

It is also possible that the tool is formed integrally with the tool holder. In that case, the user can replace the tool only by replacing the tool holder.

The tool holder is rotatably connected in operation with the rotatable spindle part. This means that the tool rotates in operation together with the tool holder and the rotatable spindle part. This rotation is relative to the fixed drive unit about the axis of rotation of the device. For this purpose, the rotatable spindle part is rotatably mounted relative to the static spindle part. Preferably, corresponding bearings are provided between the static spindle part and the rotatable spindle part.

Preferably, the transmission of electrical energy in a central portion of the spindle or in a portion of the spindle in the vicinity of the second end face (ie, the bottom or the tool holder facing). In particular, the inner coil (which may possibly also be referred to as secondary coil) may be provided immediately adjacent to a bearing of the spindle. This can be used to reduce dynamic interference effects.

The drive unit, with which the described spindle can be connected, preferably comprises a motor, which may in particular be an electric motor. With the motor, the rotatable spindle part can be rotated relative to the drive unit about a spindle axis of the spindle, which preferably coincides with the axis of rotation of the device. The spindle axis is thus the axis about which the rotating spindle part (and thus also the tool holder and the tool) are rotated during operation.

With the described spindle or with the device, it is possible, in particular, to transmit electrical energy without contact from the drive unit to the static spindle part as a fixed part of the device to the spindle part rotatable relative thereto as a rotating part of the device. This is done via an inductive coupling between the outer coil (which may possibly also be referred to as a primary coil) on the static spindle part and the inner coil on the rotatable spindle part. Preferably, the drive unit has an AC voltage source, via which an AC voltage can be coupled into the outer coil. The alternating voltage generates a magnetic alternating field from the outer coil. The inner coil is arranged within the magnetic alternating field generated in such a way that an AC voltage is induced in the inner coil. In this way, electrical energy can be transmitted from the drive unit via the static spindle part, the outer coil and the inner coil to the rotatable spindle part. There is no current flowing from the outer coil to the inner coil. Instead, the transmission of electrical energy takes place inductively and thus without contact.

The outer coil is preferably non-rotatably connected to the static spindle part. If the spindle is connected to the device, the outer coil is also rotationally fixed relative to the drive unit. The inner coil is preferably non-rotatably connected to the rotatable spindle part. That means that the Internal coil rotates in operation together with the rotatable spindle part relative to the outer coil or to the static spindle part and the drive unit.

A particularly efficient transmission of electrical energy can be achieved in the present device in that the outer coil and the inner coil are arranged inside each other. Under such an arrangement is to be understood that the outer coil surrounds the inner coil at least partially. The inner coil and the outer coil are preferably both in a common plane, which is aligned normal or perpendicular to an axis of the spindle and the drive unit. Such an orientation of the inner coil and the outer coil to each other can also be referred to as "engagement" of the inner coil in the outer coil or a "nested arrangement".

In particular milling machines can be equipped with several different tool holders. As part of the automation milling machines are equipped with various tools that can be placed in a magazine within the milling machine. This allows the fully automated machining of workpieces, where for manufacturing reasons, different milling tools must be used. Since more than one tool holder is therefore to be used, it would be disadvantageous to have to provide each tool holder with coils. With the spindle described can be dispensed with coils on the tool holders. Not only can this reduce the cost of a tool holder, but it can also facilitate the development of the tool holder. This is due in particular to the fact that coils on the tool holder can impair its concentricity properties. When using the spindle described it is sufficient if the tool holder has, for example, plug contacts.

In a preferred embodiment of the device, the outer coil has an outer coil diameter and the inner coil has an inner coil diameter which is smaller than the outer coil diameter.

A particularly small inner coil diameter is particularly advantageous for particularly high rotational speeds of the rotatable spindle part. In operation, the inner spool rotates at the speed of the rotatable spindle part. It can attack particularly large centrifugal forces on the inner coil. The larger the inner coil diameter, the larger these centrifugal forces. A maximum usable speed of the device can therefore be determined in particular by material properties of the inner coil. The smaller the inner coil diameter, the larger the maximum usable speed of the device can be.

As materials for the inner coil (or secondary coil) and / or the outer coil (or primary coil) are preferably ferromagnetic iron alloys used. It is preferred electrotechnically particularly effective alloys for the stator (here the outer coil) and electrotechnically less effective, but mechanically better alloys for the rotor (here the inner coil) is used. However, there are also special alloys that combine both properties. Typical such materials are ferromagnetic alloys of iron, nickel and cobalt. Also preferred is the use of AlNiCo, SmCo, Nd2Fe14B, Ni80Fe20 (commonly called "permalloy"), or NiFeCo alloys (often called "mu-metal"). For example, such materials are known under the following brands: MUMETALL® / VACOPERM® 100 (80% NiFe), CRYOPERM® 10 (80% NiFe), VACOFLUX® / VACODUR® (50% CoFe), TRAFOPERM® (3% SiFe), VITROVAC ® 6025 X (80% Co).

The outer coil and / or the inner coil are preferably designed as cylindrical coils. In this case, the inner coil diameter or the outer coil diameter is the cylinder diameter of the respective coil. If the coils are designed differently, the respective coil diameter is defined analogously.

In a further preferred embodiment of the device, the outer coil has an outer coil axis and the inner coil has an inner coil axis, wherein the outer coil axis and / or the inner coil axis coincide with a spindle axis of the spindle.

Preferably, both the outer coil axis and the inner coil axis coincide with the spindle axis. In that case, the outer coil axis and the inner coil axis also coincide with each other.

The outer coil and / or the inner coil are preferably cylindrical. In this case, the outer coil axis or the inner coil axis is the cylinder axis of the respective coil. If the coils are designed differently, the respective coil axis is defined analogously.

The outer coil preferably has an outer coil winding and the inner coil preferably has an inner coil winding. The respective coil winding is preferably formed in particular around the corresponding coil axis circumferentially. For a solenoid, this means that the coil winding is provided along the circumference of the cylinder barrel of the solenoid.

Along an axis of the spindle, the inner coil and the outer coil both preferably extend over a certain height. For example, the outer coil and the inner coil each have a height of 1 to 5 cm [centimeters]. Preferably, center planes (middle planes) of the inner coil and the outer coil are superposed on each other in the above-described common plane. In embodiments, it is also possible that the center planes of the inner coil and the outer coil are not exactly on top of each other, but are displaced relative to each other according to a distance of, for example, 0 cm to 5 cm along the axis. In this embodiment, however, it is preferred that the heights of the coils overlap one another. Thus, a good power transmission of the outer coil can be achieved on the inner coil. In a further particularly preferred embodiment, the outer coil overlaps the inner coil in both directions along the axis (upwards and downwards). This further improves the power transfer from the outer coil to the inner coil.

If the inner coil axis coincides with the spindle axis, the inner coil is rotated around its own axis during operation. This is particularly advantageous because otherwise it could come to significant vibration. If the outer coil axis also coincides with the spindle axis and the inner coil, a gap between the inner coil and the outer coil can be designed to be particularly narrow. As a result, electrical energy from the outer coil can be transmitted to the inner coil in a particularly low-loss manner and therefore particularly efficiently. This is further promoted by the fact that the magnetic field generated by the outer coil in the case has a particularly high flux density in the region of the inner coil.

In a further preferred embodiment of the device, the outer coil has an outer coil winding and the inner coil has an inner coil winding, wherein the outer coil winding and / or the inner coil winding are extended in a longitudinal direction of the device.

Preferably, both the outer coil winding and the inner coil winding are extended in the longitudinal direction of the device.

The longitudinal direction of the device is defined along the axis of rotation. The inner coil axis and the outer coil axis are preferably arranged parallel to the longitudinal direction.

The respective coil winding is preferably designed as a wire which is wound around the respective coil axis circumferentially. That the inner coil winding, or the outer coil winding are designed extended in the longitudinal direction, in particular means that the respective wire is not wound up in a plane perpendicular to the longitudinal direction. In particular, when the outer coil and / or the inner coil are formed as cylindrical coils having a coil axis along the longitudinal direction, the respective coil winding is extended in the longitudinal direction. Coil heights of the inner coil and the outer coil each extend along the longitudinal direction.

In a further preferred embodiment of the device, the outer coil is arranged concentrically around the inner coil.

In this embodiment, the outer coil diameter is larger than the inner coil diameter. This results in the corresponding advantages described above.

If the inner coil and the outer coil are cylindrical, the inner coil and the outer coil can in particular be arranged nested in one another such that a gap with the shape of a thin hollow cylinder results between the two coils. By such an arrangement, the magnetic field generated by the outer coil in the region of the inner coil can have a particularly high flux density, so that the electrical energy can be transferred particularly well from the outer coil to the inner coil.

In a further preferred embodiment of the device, the interface for the tool holder is embodied and connected to the inner coil or secondary coil such that at least electrical energy can be transmitted from the inner coil or secondary coil to the tool holder via the interface.

In this embodiment, the tool holder may in particular comprise electrically driven components.

In a further preferred embodiment of the device, a tool holder with a vibration generator is connected to the interface such that the vibration generator can be supplied with electrical energy via the interface.

The vibration generator may in particular be an electrically drivable component in the sense of the previously described embodiment. The vibration generator is preferably a piezoelectric element. The piezo element is preferably arranged in the tool holder and oriented in such a way that at least the tool can be set into oscillations along the longitudinal direction of the device by the piezo element. Alternatively, the vibration excitation can also be done in other directions. Thus, for example, when milling with a milling head as a tool, a particularly high material removal of a workpiece to be machined and a correspondingly high processing speed can be achieved.

The vibration generator can in particular be driven by the drive unit or the electrical energy transmitted by the static spindle part to the rotatable spindle part. For this purpose, the vibration generator is preferably connected via the interface with the inner coil. An alternating voltage induced in the inner coil as described above can be applied directly to the vibration generator. But it is also possible that the induced voltage in the inner coil is transformed before it is applied to the vibration generator.

As a further aspect, a use of the described apparatus for the ultrasonic machining of workpieces is presented, wherein the tool rotates at a peripheral speed of at least 20 m / s [meters per second], in particular of at least 55 m / s.

As a further aspect, a use of the described device for the ultrasonic machining of workpieces is presented, wherein during machining with a tool a cutting speed of at least 20 m / min [meters per minute] is set, in particular a cutting speed in the range up to 350 m / min ,

The use in particular serves the (final or ultra-precise) machining of a (in particular curved or curved) surface of a workpiece. Here, in particular, a cutting tool is used.

By way of example, the following cutting speeds are possible or set in the ultrasonic machining of workpieces of different materials with carbide tools: Ultrasonic drilling: material cutting speed [Unit] [M / min] CFK 120 to 180, especially above 150 Nickel-based material 24 to 36, especially above 30 Titanium-based material 40 to 60, especially above 50 aluminum 160 to 240, especially above 200 stole 55 to 85, especially above 70 Ultrasonic milling: material cutting speed [Unit] [M / min] CFK 160 to 240, especially above 200 Nickel-based material 40 to 60, especially above 50 Titanium-based material 55 to 85, especially above 70 aluminum 250 to 350, especially above 300 stole 80 to 120, especially above 100

The device is in particular provided with a tool holder according to HSK, SK, or BT standard, in particular according to HSK 63 (FIG. DIN 69893 In particular, circumferential speeds above 55 m / s are set and an ultrasonic excitation is activated.

The particular advantages and design features described above for the device are applicable to the described use and transferable, and vice versa. The described embodiment of the device, the described high peripheral speeds are possible.

As a further aspect, a controller for the described device is presented, which is set up for demand-driven control of the vibration generator.

The particular advantages and design features described above for the device and for use are applicable to the described control and transferable, and vice versa.

• 1: eine Darstellung einer Vorrichtung zum rotatorischen Antrieb eines Werkzeugs mit einer Spindel.

The invention and the technical environment will be explained in more detail with reference to the figure. The figure shows a particularly preferred embodiment, to which the invention is not limited. In particular, it should be noted that the figure and in particular the illustrated proportions are only schematic. It shows:

• 1 : An illustration of a device for rotatably driving a tool with a spindle.

1 shows a device 1 for rotatory drive of a tool 6 , The tool 6 can with the device 1 as indicated by a round arrow about a rotation axis 22 to be turned around.

The device 1 has a drive unit 26 on, to which a spindle 27 is connected. The spindle 27 has a rotatable spindle part 3 on, relative to the drive unit 26 around a spindle axis 11 that with the rotation axis 22 coincides, is rotatable. In addition, the spindle has 27 a static spindle part 2 on, the rotation with the drive unit 26 connected is. The spindle 27 has a first face 18 and one of the first end face 18 opposite second end face 19 , Between the first front 18 and the second end face 19 are storages 25 provided, via which the rotatable spindle part 3 relative to the static spindle part 2 rotatably mounted. At the first end 18 is the spindle 27 on the drive unit 26 held.

Furthermore, the rotatable spindle part 3 on the second front side 19 an interface 5 for a tool holder 4 for the tool 6 on. The tool holder 4 and the tool 6 are not components of the device 1 , The tool holder 4 Can be interchangeable with the rotatable spindle part 3 be connected and the tool 6 Can be interchangeable with the tool holder 4 get connected. In the example of 1 the case is shown that the tool holder 4 with the rotatable spindle part 3 connected and that the tool 6 with the tool holder 4 connected is. Here is the tool holder 4 non-rotatable with the rotatable spindle part 3 and the tool 6 rotatably with the tool holder 4 connected.

The static spindle part 2 has a 7 and the rotatable spindle part 3 an inner coil 8th on. The outer coil 7 and the inner coil 8th are for a contactless transmission of electrical energy from the drive unit 26 over the static spindle part 2 , the outside coil 7 and the inner coil 8th on the rotatable spindle part 3 concentrically arranged around each other and engaging each other. The electrical energy can in particular be used as an alternating voltage from an alternating voltage source 12 provided and in the outer coil 7 directed and inductively on the inner coil 8th be transmitted. The outer coil 7 has an outer coil axis 9 and the inner coil 8th an inner coil axis 10 on. The outer coil axis 9 and the inner coil axis 10 fall with the spindle axis 11 the spindle 27 as well as with the rotation axis 22 together. The inner coil 8th and the outside coil 7 have along the coil axes 9 . 10 one coil height each 23 and a normal or perpendicular to the coil axes 9 . 10 aligned coil center plane 24 , The coil heights 23 overlap here exactly. The coil middle planes 24 lie here exactly on each other. This is a preferred embodiment. Embodiments are also possible in which the coil middle planes 24 offset from one another and the coil heights are arranged 23 only partially overlap.

the interface 5 for the tool holder 4 is designed in such a way and with the inner coil 8th connected that over the interface 5 at least electrical energy from the inner coil 8th on the tool holder 4 can be transmitted contacting. The energy transferring contact means that leads are in direct contact with each other, allowing current to flow along a continuous conduction path. In contrast to a contacting transmission of energy is a non-contact transmission in which a conduction path is interrupted and the energy is transmitted, for example, inductively beyond the interruption. The tool holder 4 has a vibration generator 20 on and is so at the interface 5 Tethered that the vibration generator 20 over the interface 5 can be supplied with electrical energy. A controller 21 is to the AC voltage source 12 tethered. The control 21 is in particular for demand-driven control of the vibration generator 20 set up.

The outer coil 7 has an outer coil diameter 16 and the inner coil 8th an inner coil diameter 17 on. The inner coil diameter 17 is smaller than the outer coil diameter 16 ,

The outer coil 7 has an outer coil winding 13 and the inside coil 8th an inner coil winding 14 on. The outer coil winding 13 and the inner coil winding 14 are in a longitudinal direction 15 the device 1 extended.

LIST OF REFERENCE NUMBERS

1

contraption

2

static spindle part

3

rotatable spindle part

4

toolholder

5

interface

6

Tool

7

outer coil

8th

inner coil

9

Outer coil axis

10

Inner coil axis

11

spindle axis

12

AC voltage source

13

Outer coil winding

14

Indoor coil winding

15

longitudinal direction

16

Outside coil diameter

17

Inside coil diameter

18

first end face

19

second end face

20

vibration generator

21

control

22

axis of rotation

23

coil height

24

Coil center plane

25

storage

26

drive unit

27

spindle

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• DIN 69893 [0047]

Claims (9)

Spindle (27) for a device (1) for rotary drive of a tool (6), comprising at least: - A static spindle part (2) rotatably connected to a drive unit (26) of the device (1) is connectable, and - A rotatable spindle part (3) which is rotatably mounted relative to the static spindle part (2) on the static spindle part (2) and which has an interface (5) for a tool holder (4) for the tool (6), via the the tool holder (4) can be connected in a rotationally fixed manner to the rotatable spindle part (3), wherein the static spindle part (2) has an outer coil (7), and the rotatable spindle part (3) has an inner coil (8), and wherein the outer coil (7 ) and the inner coil (8) for non-contact transmission of electrical energy from the static spindle part (2) via the outer coil (7) and the inner coil (8) on the rotatable spindle part (3) are arranged one inside the other. Spindle (27) to Claim 1 wherein the outer coil (7) has an outer coil diameter (16), and wherein the inner coil (8) has an inner coil diameter (17) smaller than the outer coil diameter (16). A spindle (27) according to any one of the preceding claims, wherein the outer coil (7) has an outer coil winding (13) and the inner coil (8) has an inner coil winding (14), and wherein at least the outer coil winding (13) or the inner coil winding (14) a longitudinal direction (15) of the device (1) are expanded. Spindle (27) according to one of the preceding claims, wherein the outer coil (7) is arranged concentrically around the inner coil (8). Spindle (27) according to one of the preceding claims, wherein the interface (5) for the tool holder (4) is designed and connected to the inner coil (8), that at least electrical energy from the inner coil (8) via the interface (5). can be transmitted to the tool holder (4) contacting. Spindle (27) according to one of the preceding claims, wherein a tool holder (4) with a vibration generator (20) is connected to the interface (5) such that the vibration generator (20) via the interface (5) can be supplied with electrical energy. Use of a spindle (27) according to one of the preceding claims for the ultrasonic machining of workpieces, wherein the tool (6) is connected to the spindle (27) and a cutting speed of at least 20 m / min is set. Device (1) for rotary drive of a tool (6), comprising a spindle (27) according to one of Claims 1 to 6 , Control (21) for a device (1) according to Claim 8 , which is set up for the demand-driven activation of the vibration generator (20).

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