WO2023217734A1

WO2023217734A1 - Rotor assembly for a tool spindle

Info

Publication number: WO2023217734A1
Application number: PCT/EP2023/062194
Authority: WO
Inventors: Michel Müller
Original assignee: Reishauer Ag
Priority date: 2022-05-09
Filing date: 2023-05-09
Publication date: 2023-11-16
Also published as: EP4294592A1; CH719179B1

Abstract

The invention relates to a rotor assembly (4) for a tool spindle (2), having - a hollow rotor (8), - an actuation device (10) for actuating a clamping device (12) for releasably fastening a tool holder (90) to the rotor (8), wherein the actuation device (10) has a pull rod (30) and a piston (32) rigidly coupled to the pull rod (30), which are movably mounted together along a movement direction (VR) in the hollow rotor (8), wherein the pull rod (30) is preloaded into a clamping position (SSt) by means of a spring device (54) and can be brought into a release position against the preloading force of the spring device (54) through the application of fluid pressure to the piston (32), wherein in the rotor (8), the piston (32) separates a pressure space (46) and a cooling space (42) from one another, wherein in the piston (8), at least one check valve (76) is provided which permits an inflow of fluid from the cooling space (42) into the pressure space (46) and prevents an outflow of fluid from the pressure space (46) into the cooling space (42), wherein a first fluid connection (78) is provided which is fluidically connected to the pressure space (46), wherein in the pull rod (30), a fluid guide (56) is formed through which fluid can be introduced into the cooling space (42), and wherein a second fluid connection (80) is provided which is fluidically connected to the fluid guide (56). The invention makes possible an automated tool change on a simply constructed and effectively coolable tool spindle.

Description

Rotor assembly for a tool spindle

Background of the invention

The invention relates to a rotor assembly for a tool spindle, comprising a hollow rotor and an actuating device for actuating a clamping device for releasably attaching a tool holder to the rotor. The invention further relates to a tool spindle, an actuating device for a rotor assembly of a tool spindle and an operating method for a rotor assembly or a tool spindle. Machine tools, such as gear grinding machines or machine tools for hard precision machining, have a tool spindle (often also referred to as a work spindle or machine spindle). The tool spindle is used to hold the tool and drives the tool. The tool can be attached to a rotor of the tool spindle using a tool holder, for example a grinding wheel flange. For this purpose, it is generally known to align the tool holder on the rotor using a cone and a flat contact and to screw it manually to the rotor. With this mounting variant, internal cooling of the rotor can be easily set up.

Due to the increasing automation and digitalization in industrial production (often referred to as Industry 4.0), automated setup processes for machine tools are particularly in demand. Tool clamping systems with a tool holder are often used for automated tool changing. On the one hand, the tool holder is connected to the tool and, on the other hand, can be automatically attached to the rotor or detached from the rotor. Known tool holders are designed, for example, as so-called hollow shaft cones, steep tapers or polygonal shaft cones. To attach such tool holders to the rotor, a clamping system is required, which takes up space inside the rotor. Cooling, as with tools screwed manually to the rotor, is then no longer possible.

From EP 3 275 589 B1 a machine tool processing unit has become known which comprises a rotor with a clamping device integrated in the rotor for releasably holding a tool holder and a cooling device for the rotor. Coolant flow channels with an inlet opening and coolant return channels with an outlet opening are installed in the rotor. The coolant flow channels and the coolant return channels are connected to one another via an annular channel. The cooling device has connections for supplying and discharging coolant. Furthermore, the cooling device has channels for the coolant, which are connected to the channels of the rotor are connected. The cooling device also has an actuating device with which the clamping device can be actuated.

The disadvantage of this machine tool processing unit is that the cooling channels installed in the rotor can impair the stability of the rotor. In addition, the production of the coolant channels and the annular channel is complex.

From the catalog "CyMill - CySpeed milling head and motor spindle technology" from CyTec cylinder technology GmbH, Jülich, Germany, November 2006 edition, a tool spindle has become known which has a rotor with an integrated clamping system with several channels and channel circuits, cf. in particular Catalog page 51. A clamping connection and a release connection are provided for tightening and loosening the clamping system. If high-pressure coolant is supplied to two coolant connections at the same time, a valve opens so that the coolant emerges from a tool holder. If low-pressure coolant is supplied to only one of the coolant connections When pressure is supplied, the valve directs the coolant to the other coolant connection where it emerges. In this way, circulation cooling can be set up.

With this tool spindle, a complex network of channels must also be manufactured in the rotor and clamping system. In addition, the cooling only takes place close to the rotor axis and is therefore relatively far away from the place where heat is generated on the outside of the rotor.

It is the object of the invention to enable an automated tool change on a simply constructed and effectively coolable tool spindle. Short

the

This object is achieved according to the invention by a rotor assembly group for a tool spindle, having a hollow rotor, an actuating device for actuating a clamping device for releasably attaching a tool holder to the rotor, the actuating device having a pull rod and a piston rigidly coupled to the pull rod, which together are mounted movably along a travel direction in the hollow rotor, in particular wherein the travel direction corresponds to the direction of an axis of rotation of the rotor, wherein the pull rod is biased into a clamping position by a spring device and can be brought into a release position against the biasing force of the spring device by applying fluid pressure to the piston , wherein the piston in the rotor separates a pressure chamber and a cooling chamber from one another, with at least one check valve being provided in the piston, which allows fluid to flow from the cooling chamber into the pressure chamber and prevents fluid from flowing out of the pressure chamber into the cooling chamber, wherein a first fluid connection is provided, which is fluidly connected to the pressure chamber, a fluid guide being formed in the pull rod, through which fluid can be introduced into the cooling space, and a second fluid connection being provided, which is fluidly connected to the fluid guide.

The invention provides a rotor assembly for automated tool changing on a machine tool. The invention enables the clamping device to be actuated and the rotor to be cooled in a simple manner by appropriately introducing or removing fluid at the two fluid connections. The rotor assembly has a hollow rotor and an actuator. The actuating device is at least partially arranged in a cavity of the rotor. The rotor typically has openings at its ends. The actuating device can protrude from the rotor at at least one end. A clamping device can be arranged in the area of an opening, with which a tool holder can be attached to the rotor.

The actuating device serves to actuate the clamping device and thus attach the tool holder to the rotor or to detach it from the rotor. A tool can be attached to the rotor indirectly via the tool holder. For this purpose, the tool holder can be clamped by the clamping device against a receptacle on the rotor, with an end region of the tie rod engaging on the clamping device.

The pull rod and the piston of the actuating device are rigidly coupled to one another. The pull rod and the piston can therefore be moved together but not relative to one another. The tie rod and piston can be moved along a travel direction in the hollow rotor. Depending on the position of the pull rod in the rotor, the tool holder can be held or released on the rotor.

The pull rod is pretensioned into a clamping position by a spring device. In this clamping position, the tool holder can be secured to the rotor using the clamping device.

The pull rod and the piston are basically tightly connected to each other. The piston can be displaced together with the pull rod against the preload force of the spring device by building up a fluid pressure in the pressure chamber and exerting it on the piston. The pull rod can thereby be moved into the release position. When the pull rod is in the release position, the clamping device is open. The tool holder can be detached from the rotor or placed on the rotor. The release position is typically defined by a stop of the tie rod or piston on the rotor. The pressure chamber and the cooling chamber are formed in the rotor. The first fluid connection makes it possible to introduce fluid into the pressure chamber and to discharge it from the pressure chamber. The second fluid connection enables fluid to be introduced into the cooling space through the fluid guide in the tie rod. The at least one check valve in the piston allows fluid to flow from the cooling chamber into the pressure chamber, but not from the pressure chamber into the cooling chamber. The pressure chamber, the cooling chamber, the fluid guide and the first and second fluid connections can collectively be referred to as a fluid channel system.

The fluid guide is usually designed with a longitudinal bore in the tie rod, the longitudinal bore being radially closed (apart from the mouths of transverse bores). The longitudinal bore can run centrally in the tie rod, in particular on the axis of rotation of the rotor.

The rotor and piston are part of the boundary of the pressure chamber and the cooling chamber. The cooling space is typically limited by an inner wall of the rotor, an outer wall of the tie rod and the piston. The cooling chamber is designed to be fluid-tight (apart from the openings from the fluid guide in the tie rod and to the at least one check valve), in particular with seals between the tie rod and the rotor and between the piston and the rotor.

The tie rod protrudes through the cooling chamber along the direction of travel. Typically, the tie rod also protrudes through the pressure chamber along the direction of travel. The tie rod typically runs coaxially to the axis of rotation of the rotor

The fluid channel system can be used to set up a cooling operation for the rotor assembly and to operate the actuating device in order to open the clamping device for a tool change. If a fluid (for example hydraulic oil) is introduced into the fluid guide under moderate pressure (typically 2 to 15 bar) via the second fluid connection, the fluid can Flow through the cooling chamber and cool the rotor. The fluid can continue to flow from the cooling chamber into the pressure chamber via the at least one check valve and can be discharged from the rotor via the first fluid connection. The fluid also cools the rotor as it flows through the pressure chamber. However, if fluid is introduced into the pressure chamber under high pressure (typically 160 to 180 bar) via the first fluid connection, the at least one check valve closes. Pressure builds up in the pressure chamber and the piston with the pull rod is moved against the spring force of the spring device. This opens the clamping device so that the tool holder can be removed from the rotor or attached to the rotor. Arranging the tool holder on the rotor or removing the tool holder from the rotor can be done automatically.

The separation of the pressure chamber from the cooling chamber or their connection via the check valve enables the rotor assembly to be easily upgraded for cooling operation and automated tool changing. The fluid guidance in the tie rod enables fluid to be introduced into the cooling chamber in order to cool the rotor. The fluid guide can be manufactured efficiently using a longitudinal bore and typically a transverse bore. Reliable check valves are available at low cost. The piston can thus be fluid-tight in one direction (from the pressure chamber to the cooling chamber), while a flow through the piston is enabled in the other direction (from the cooling chamber to the pressure chamber).

Preferred variants of the invention

In a particularly preferred embodiment of the rotor assembly according to the invention it is provided that the spring device is arranged in the cooling space. During operation of the rotor assembly (when the rotor assembly is rotating and being cooled), the cooling space is filled with fluid. The spring device is therefore in the fluid during operation. The fluid has a damping effect on the spring device. This allows vibrations of the spring device to be reduced. In addition, the space required anyway used to accommodate the spring device for cooling the rotor. This allows the available space in the hollow rotor to be used efficiently while the rotor remains simple to construct. The spring device is in particular arranged between an inner wall of the rotor and an outer wall of the tie rod.

The spring device is advantageously designed as a plate spring package. In other words, the spring device can be formed with a large number of successive disc springs, in particular connected in parallel and/or in series. The disc springs can in particular be connected in parallel in pairs, with pairs of parallel disc springs being connected in series with one another. The use of a disc spring package enables the provision of a spring device with sufficiently high rigidity, preload and deformability.

In a further preferred embodiment it is provided that the spring device is supported at one end via a support disk on the rotor and at the other end on the piston. The spring force of the spring device, which is supported on the support disk, can be introduced evenly into the rotor via the support disk (for example on a shoulder in the rotor). Furthermore, the support disk avoids direct contact between the rotor and the spring device. The support disk can be made of a harder material than the rotor. The piston projects in the radial direction beyond the tie rod and is rigidly connected to it; the piston therefore allows force to be transmitted to the tie rod. A surface suitable for supporting the spring device can be set up on the piston. The spring force can be distributed evenly across the piston.

Particularly preferred is a further development in which the fluid guide, viewed from the spring device, opens into the cooling space beyond the support disk. This makes it possible to easily set up a uniform flow direction for the fluid for cooling the rotor in the area of the spring device (e.g. in a main cooling chamber), and the support disk can be inserted into the Flow design can be included. The creation of dead space areas in the cooling chamber with no or only uneven flow can at least largely be avoided. In addition, the volume inside the rotor through which the fluid flows for cooling can be increased.

Also preferred is a further development in which the support disk has at least one overflow channel for the fluid, preferably several overflow channels arranged rotationally symmetrically to an axis of rotation of the rotor. With the overflow channels, the fluid can be guided in the area of the support disk with low flow resistance, in particular it can be transferred from a front, radially narrow part of the cooling space, into which the fluid guide opens (e.g. a cooling space annular channel), into a rear, radially wider part the cooling room in which the spring device is also arranged (e.g. a main cooling room). The at least one overflow channel can run radially and/or axially on the support disk. In particular, depressions in the support disk can form the overflow channels. Such overflow channels can be easily manufactured. Radial overflow channels can be provided on one or both sides of the support disk. When using multiple transfer channels, the rotationally symmetrical arrangement can prevent an imbalance from occurring during use of the rotor assembly. Furthermore, the fluid can flow particularly evenly and there is more cross section available for the flow of the fluid.

A further development is also preferred in which an inner diameter of the support disk is larger than an outer diameter of the tie rod in the area of the support disk, preferably by at least 5%, particularly preferably by at least 10%. This creates a space between the pull rod and the support disk. The fluid can flow through the gap. The inner diameter of the support disk can be easily adjusted from a technical point of view.

Also preferred is an embodiment in which a plurality of check valves are provided in the piston, which are preferably arranged rotationally symmetrically to an axis of rotation of the rotor. The flow of fluid through the This means that the cold storage space can be used particularly evenly. The resistance to flow through the piston is reduced. The rotationally symmetrical arrangement of the check valves can also prevent imbalance from occurring. This can prevent premature wear of the rotor assembly.

Very particularly preferred is an embodiment in which the fluid guide in the tie rod has a longitudinal bore along an axis of rotation of the rotor and a first transverse bore which fluidly connects the longitudinal bore to the cooling chamber, preferably wherein the first transverse bore runs radially to the axis of rotation. The longitudinal hole and the first cross hole are easy to make. The longitudinal bore generally does not noticeably affect the stability of the tie rod. A fluid can be easily guided into the cooling space via the longitudinal bore and the transverse bore.

A further development is advantageous which provides that the longitudinal bore is closed at an end remote from the pressure chamber. This forces the fluid to flow from the longitudinal bore into the cooling space. The longitudinal bore extends at least to the transverse bore; However, the fluid-carrying longitudinal bore ends within the tie rod.

An embodiment is also preferred in which it is provided that the piston and the pull rod are in one piece with one another. This makes it particularly easy to achieve that the piston and the pull rod can be moved with one another, but not relative to one another. In addition, leaks between the piston and the pull rod can be reliably avoided.

Also preferred is an embodiment in which the tie rod is rotationally symmetrical with respect to the axis of rotation of the rotor. The (mass) center of gravity of the tie rod is therefore on the axis of rotation of the rotor. Dynamic imbalance can also be avoided. This counteracts premature wear of the rotor assembly. Particularly preferred is an embodiment which provides that the actuating device further has a rotary insertion with an insertion housing and a connecting part, the insertion housing and the connecting part being rotatable relative to one another, the first fluid connection and the second fluid connection being formed on the insertion housing, and wherein the Connecting part fluidly connects the first fluid connection to the pressure chamber and fluidly connects the second fluid connection to the fluid guide in the pull rod. The rotary introduction makes it possible to guide fluid to and from the rotating rotor with stationary fluid connections. The connecting part is firmly connected to the rotor during operation of the tool spindle, for example screwed to the rotor. In particular, the connecting part rotates with the rotor during operation. The connecting part can be in several pieces or preferably in one piece. The insertion housing does not rotate with the rotor when the tool spindle is in operation, but generally remains at rest. Typically, the piston, the outer wall of the tie rod, the inner wall of the rotor and the connecting part limit the pressure chamber.

In an advantageous development it is provided that the tie rod extends into the connecting part. The connecting part can have a recess into which the tie rod projects in the axial direction. This makes it easier to set up the fluidic connection between the second fluid connection and the fluid guide in the tie rod. The tie rod may have a tie rod main body and an extension rigidly connected to the tie rod main body, the extension extending into the connecting part. The extension can be screwed to the tie rod main body.

An advantageous further development of this development provides that an annular channel is formed between the pull rod and the connecting part, via which the first fluid connection is fluidly connected to the pressure chamber. This ring channel can be easily set up. Fluid can from the first Fluid connection passes into the pressure chamber via the annular channel. In the area of the annular channel, an inner diameter of the connecting part is fundamentally larger than an outer diameter of the tie rod, preferably by at least 5%, particularly preferably by at least 10%. Typically, in the area of the annular channel, the inside diameter of the connecting part is at most 20%, preferably at most 15%, larger than the outside diameter of the tie rod.

In a further advantageous development, it is provided that the annular channel is fluidly connected to the first fluid connection on the insertion housing via at least one first radial bore in the connecting part, a first channel running in the circumferential direction being formed between the connecting part and the insertion housing, which is connected to the at least one first radial bore and the first fluid connection is fluidly connected. The fluidic connection of the (stationary) first fluid connection to the pressure chamber through the (rotating) connecting part is thus made possible in a simple manner.

Particularly preferred is a further development which is characterized in that the connecting part is fixed to the rotor, that a pocket is formed between the pull rod and the connecting part, which is fluidly connected to the second fluid connection via a second radial bore in the connecting part, that the pull rod has a has a second transverse bore, which fluidly connects a longitudinal bore of the fluid guide in the pull rod to the pocket, and that the pocket extends along the direction of travel to such an extent that from the clamping position to the release position, the longitudinal bore over the second transverse bore, the pocket and the second radial bore remains fluidly connected to the second fluid connection, in particular wherein the pocket is formed in the connecting part, preferably as a circumferential groove. The connecting part does not move relative to the rotor. When the pull rod is moved from the clamping position to the release position or vice versa, the pocket ensures that the fluid guide in the pull rod is fluidly connected to the second fluid connection at all times during the movement of the pull rod. When moving the tie rod from the clamping position to the In the release position, part of the fluid in the cooling chamber is typically pushed back into the fluid guide. The continuous connection of the fluid guide of the tie rod and the second fluid connection can ensure that the fluid that was previously used for cooling can exit the rotor assembly and does not block the movement of the tie rod. An axial extent of the pocket is at least as large as the distance covered by the pull rod between the clamping position and the release position, in particular plus a diameter of the second transverse bore. The second transverse bore preferably runs radially to the axis of rotation.

In a preferred further development of this development, a second circumferentially running channel is formed between the connecting part and the insertion housing, which is fluidly connected to the at least one second radial bore and the second fluid connection. The fluidic connection of the (stationary) second fluid connection with the fluid guide in the tie rod through the (rotating) connecting part is thus made possible in a simple manner.

Particularly preferred is an embodiment in which permanent magnets are attached to the rotor, the permanent magnets being arranged at least partially, preferably completely, in the area of the longitudinal extent of the cooling space. In other words, the permanent magnets are arranged entirely or at least in part in the radial direction above the cooling space. Together with a coil arrangement that is arranged around the permanent magnets, a direct drive of the rotor or a tool spindle can be set up with the rotor assembly. In the area of the permanent magnets, heat is generated during operation of the rotor assembly, particularly during acceleration and braking, which can be efficiently dissipated via the fluid in the cooling space.

Also preferred is an embodiment in which the rotor assembly has the clamping device, preferably the clamping device has a plurality of clamping elements, particularly preferably the clamping elements are arranged rotationally symmetrically to an axis of rotation of the rotor. The tool holder can be held on the rotor via the clamping device. The clamping device can be designed as a clamping set. Due to the rotationally symmetrical distribution of the clamping elements, the creation of an imbalance can be avoided. The tensioning device is arranged in the region of one end of the tie rod, which faces away from the pressure chamber. The pull rod is connected to the tensioning device in order to operate it.

Inventive measures

The scope of the present invention also includes a tool spindle having a rotor assembly according to the invention described above and a stator assembly with a spindle housing in which the rotor is rotatably mounted, preferably with a coil arrangement for driving the rotor being provided in the spindle housing. The tool spindle allows the rotor assembly to be used on a machine tool. The coil arrangement on the spindle housing and permanent magnets on the rotor form a motor of the tool spindle for direct drive of the rotor.

Inventive operating device

Also within the scope of the present invention is an actuating device for a rotor assembly of a tool spindle, in particular for a rotor assembly according to the invention described above, comprising a pull rod which has a longitudinal bore as a fluid guide, and a piston which is rigidly coupled to the pull rod and on which Pull rod is seated, so that the pull rod has a cooling chamber-side section on a first side of the piston and a pressure chamber-side section on a second side of the piston opposite the first side, the fluid guide having at least one first opening in the cooling chamber-side section and at least a second opening in the pressure chamber-side section has, in particular wherein the at least one first mouth through a first transverse bore and the at least one second mouth is formed by a second transverse bore, and at least one check valve is provided in the piston, via which the two sides of the piston are fluidly connected, the check valve being at a higher pressure on the first side than on the opens on the second side and locks at a higher pressure on the second side than on the first side. With an actuating device designed in this way, cooling of the rotor of the rotor assembly can be set up and a tool can be changed automatically. In particular, the actuating device makes it possible to equip a rotor for cooling. For cooling a rotor assembly with the actuating device, fluid for cooling is introduced via the second transverse bore into the fluid guide in the area of the pressure chamber-side section of the tie rod. The fluid flows through the fluid guide in the area of the pressure chamber-side section and then also in the area of the cooling chamber-side section of the tie rod. The fluid exits the fluid guide at the first transverse bore and passes into the cooling chamber. In the cooling chamber, the fluid can be used for cooling, flowing to the first side of the piston on the outside of the cooling chamber-side section of the tie rod. The flowing fluid opens the check valve so that the fluid can flow through the piston and enter the pressure chamber on the second side of the piston. In order to open a clamping device by means of the actuating device for fastening or releasing a tool holder, fluid is guided under high pressure to the second side of the piston. The check valve closes so that the fluid cannot flow into the refrigerator compartment. The piston with the pull rod is moved into a release position by the increased pressure, so that the clamping device is opened and a tool holder can be released from or attached to the rotor.

Operating procedures

Furthermore, the scope of the invention includes an operating method for a rotor assembly according to the invention described above or a tool spindle according to the invention described above, wherein in a cooling mode fluid, in particular oil, is introduced into the fluid guide through the second fluid connection so that it flows through the cooling space the at least one check valve flows into the pressure chamber and is discharged through the first fluid connection, and wherein in a release mode, fluid is introduced into the pressure chamber through the first fluid connection, so that a release pressure is built up in the pressure chamber, through which the pull rod counteracts the action of the spring device is brought into the release position by means of the piston. Using the rotor assembly or tool spindle according to the invention with only two fluid connections, this method enables, on the one hand, cooling of the rotor and, on the other hand, automated tool changing. To switch between the cooling mode and the release mode, only the pressure of the fluid applied to the two fluid connections must be selected accordingly. In cooling mode, the rotor can be cooled with fluid flowing through the cooling space. In the cooling mode, the tie rod is in the clamping position. Typically, in the cooling mode, the rotor rotates in the spindle housing. A tool held on the rotor by the clamping device (via a tool holder) can process a workpiece. For a tool change, the rotor is stopped and the release mode is activated. In the release mode, the rotor basically stands still. Then the tool (with the tool holder) can be removed and another tool (with another tool holder) can be arranged on the clamping device. After deactivating the release mode, the new tool is fixed to the rotor.

A variant is preferred which provides that in the cooling mode the fluid pressure at the second fluid connection is at least 2 bar, preferably at least 5 bar, and/or at most 15 bar, preferably at most 12 bar. This Pressures have proven particularly useful in practice. These pressures are sufficient to allow the fluid to flow sufficiently quickly for effective cooling and to open the at least one check valve.

Also preferred is a variant which is characterized in that in the release mode the fluid pressure at the first fluid connection is at least 120 bar, preferably at least 150 bar, and/or at most 200 bar, preferably at most 180 bar. These pressures have also proven particularly useful in practice. With these pressures, the preload of the spring device can be overcome.

Also advantageous is a variant in which the fluid is provided with at least the release pressure, and in which the fluid in the cooling mode is directed to the second fluid connection through a pressure reducer, in particular a proportional pressure control valve or a servo valve. This means that only a single conveying device is required for the fluid. The conveying device for providing the fluid can always be operated at the same pressure. To adjust the pressure, depending on the operating mode, the fluid can be guided through the pressure reducer to the second fluid connection or past it to the first fluid connection.

Further advantages of the invention result from the description and the drawing. Likewise, according to the invention, the features mentioned above and those further detailed can be used individually or in groups in any combination. The embodiments shown and described are not to be understood as an exhaustive list, but rather have an exemplary character for describing the invention. Detailed

the and

1 shows a schematic longitudinal section of a tool spindle according to the invention with a rotor assembly according to the invention in a cooling mode, with a pull rod being in a clamping position;

Fig. 2 shows a schematic longitudinal section of the tool spindle according to the invention from Fig. 1 with the rotor assembly in a release mode, with the pull rod being in a release position;

Fig. 3 shows an isolated, schematic perspective view of a support disk with overflow channels for the rotor assembly from Fig. 1;

Fig. 4a shows an opened check valve of the rotor assembly from Fig. 1;

Fig. 4b shows the check valve in the closed state according to Fig. 2;

Fig. 4c shows, isolated in three different views, a screw body of the check valve from Fig. 4a and Fig. 4b;

5a shows an isolated perspective view of a first end of a tie rod of the rotor assembly from FIG. 1 with a longitudinal bore and a first transverse bore;

Fig. 5b shows an enlarged detail from Fig. 1 in an area of the tie rod in which the first transverse bore is formed;

Fig. 6 shows an enlarged view of the rotary insert from Fig. 2 in a schematic longitudinal section;

Fig. 7 shows an isolated perspective view of the tie rod with a piston from Fig. 1; 8 shows, using a fluid diagram, the implementation of an operating method according to the invention for a rotor assembly according to the invention;

Fig. 9 shows schematically a machine tool with which a workpiece can be machined with a tool spindle according to the invention.

Figure 1 shows an example of a tool spindle 2 according to the invention. The tool spindle 2 has a rotor assembly 4 according to the invention and a stator assembly 6.

The rotor assembly 4 has a hollow rotor 8, an actuator 10 and a clamping device 12. The rotor 8 is rotatably mounted about an axis of rotation DA. The hollow rotor 8 has a front opening area 14 (tool-side opening area). Furthermore, the hollow rotor 8 has a rear opening region 16 opposite the front opening region 14. In the front opening area 14, a receptacle 18 with a projection 20 and an inner cone 22 is formed in the rotor 8. A thread 24 is formed on the rotor 8 in the rear opening area 16. Permanent magnets 28 are attached to an outside 26 of the rotor 8. The permanent magnets 28 are arranged around the rotor 8 in the circumferential direction.

The actuating device 10 has a pull rod 30, a piston 32 and a rotary insert 34. The pull rod 30 and the piston 32 are rigidly coupled (see also Fig. 7). The pull rod 30 is rotationally symmetrical to the axis of rotation DA of the rotor 8. The pull rod 30 and the piston 32 can be moved together along a travel direction VR in the rotor 8. In the embodiment shown, the travel direction VR corresponds to the direction of the axis of rotation DA of the rotor 8. The pull rod 30 is largely arranged in the rotor 8 in the embodiment shown. An end area of the Pull rod 30 is arranged in the rotary insert 34. A connecting part 120 of the rotary insert 34 is firmly connected to the rotor 8.

An outer wall 36 of the pull rod 30, an inner wall 38 of the rotor 8 and a first side 40 of the piston 32 delimit a cooling space 42 in the rotor 8. Furthermore, the outer wall 36 of the pull rod 30, the inner wall 38 of the rotor 8, delimit a second side 44 of the Piston 32 and the connecting part 120 of the rotary insert 34 have a pressure chamber 46. The cooling chamber 42 and the pressure chamber 46 are sealed in a fluid-tight manner via seals (not shown), so that fluid escapes from the front opening area 14 or the rear opening area 16 is prevented.

The cooling space 42 here comprises two sections, namely a cooling space annular channel 48 and a main cooling space 50. A diameter of the main cooling space 50 is larger than a diameter of the cooling space annular channel 48, here approximately twice as large. A support disk 52 is arranged at the transition from the cooling chamber annular channel 48 to the main cooling chamber 50. The annular support disk 52 has several overflow channels (see Fig. 3).

A spring device 54 is arranged in the cooling chamber 42 between the support disk 52 and the piston 32. The spring device 54 extends in the axial direction over the entire space between the support disk 52 and the piston 32. For the sake of clarity, the spring device 54 is only shown directly on the support disk 52 and on the first side 40 of the piston 32 in FIG. The spring device 54 here is a plate spring package 55. The plate spring package 55 consists of a large number of plate springs. In the case of the disc spring pact 55, pairs of disc springs connected in parallel are connected in series. The bias of the spring device 54 seeks to move the piston 32 with the pull rod 30 towards the rear opening area 16 towards the rotary insert 34. The pull rod 30 is biased into a clamping position SSt shown in FIG. 1 by the spring force of the spring device 54. In the clamping position SSt, the pull rod 30 extends far into the rotary insert 34. A fluid guide 56 is formed in the pull rod 30. In the embodiment shown, the fluid guide 56 is formed by a longitudinal bore 58, a first mouth 60 and a second mouth 64. The first mouth 60 is designed here as a first transverse bore 62. The second mouth 64 is designed here as a second transverse bore 66. The pull rod 30 is closed directly after the first transverse bore 62 (see also Fig. 5a, 5b); In the present case, the longitudinal bore 58 extends to the first transverse bore 62, but not to the front opening region 14 beyond the first transverse bore 62.

The pull rod 30 can be divided into a section 68 on the cooling chamber side and a section 70 on the pressure chamber side as well as an intermediate middle section 71 which runs in the area of the piston 32 and on which the piston 32 rests. The cooling chamber-side section 68 extends from the first side 40 of the piston 32 over the entire cooling chamber 42 in the rotor 8. The pressure chamber-side section 70 extends from the second side 44 of the piston 32 to a seal, not shown, between the pull rod 30 and the Rotary insertion 34. The piston 32 and the pull rod 30 are in the present case formed in one piece with each other; The piston 32, made of the same material, merges into the middle section 71 of the pull rod 30, on which it rests.

In the embodiment shown, the piston 32 has two transfer channels 72. The transfer channels 72 begin on the first side 40 of the piston 32 and end on the second side 44 of the piston 32. In the transfer channels 72 there are check valves 76 near the second side 44 of the piston 32 arranged (see Fig. 4a-4c). The check valves 76 are here arranged rotationally symmetrically with respect to the axis of rotation DA of the rotor 8. In Fig. 1, the check valves 76 are in an open position. The check valves 76 are designed so that the check valves 76 open when a fluid pressure in the cooling chamber 42 (by a typically negligible opening pressure of the check valves 76) is above the fluid pressure in the pressure chamber 46. If the If the fluid pressure in the pressure chamber 46 is above the fluid pressure in the cooling chamber 42, the check valves 76 close.

The rotary insert 34 has a first fluid connection 78. The first fluid connection 78 is fluidly connected to the pressure chamber 46. The rotary insert 34 also has a second fluid connection 80. The second fluid connection 80 is fluidly connected to the fluid guide 56 and the cooling space 42. Further details of the rotary insert 34 are described below in FIG. 6.

The clamping device 12 is arranged on the front opening area 14 of the rotor 8. The clamping device 12 is arranged here in the receptacle 18. The pull rod 30 projects into the clamping device 12 here. The clamping device 12 is designed here as a clamping set. The clamping device 18 has a plurality of clamping elements 82 and a clamping sleeve 88. The clamping sleeve 88 is attached to the pull rod 30. In the clamping position SSt, the clamping sleeve 88 spreads the clamping elements 82 radially outwards.

A tool holder 90 can be attached to the rotor 8 with the clamping device 18. The rotor 8 has the inner cone 22 on its front opening area 14 in order to accommodate the tool holder 90. Inserted into this inner cone 22 is a tapered shaft 94 of the tool holder 90 - designed here as a hollow shaft cone. The clamping sleeve 88 is moved so far in the clamping device 18 that the clamping sleeve 88 presses the clamping elements 82 outwards. The clamping elements 82 engage in the tapered shaft 94 of the tool holder 90 and fix the tool holder 90 on the rotor 8.

The stator assembly 6 has a hollow spindle housing 98. The rotor 8 is rotatably mounted in the spindle housing 98, here via several roller bearings. A coil arrangement 100 is arranged in the spindle housing 98. The coil arrangement 100 surrounds the permanent magnets 28. The coil arrangement 100 and the permanent magnets 28 lie completely in the area of the cooling chamber 42 in the direction of the rotation axis DA. The coil arrangement 100 and the Permanent magnets 28 form a direct drive for the rotor 8. In addition to the rotor assembly 4, the stator assembly 6 can also be coolable. For example, a cooling coil, not shown in detail, could be provided between the spindle housing 98 and the coil arrangement 100.

In Fig. 1, the rotor assembly 4 is in a cooling mode A. In the cooling mode A, the rotor assembly 4, in particular the rotor 8 with the permanent magnets 28, can be cooled. The cooling in Fig. 1 takes place as follows:

A fluid for cooling (for example hydraulic oil) is passed into the fluid guide 56 of the pull rod 30 via the second fluid connection 80. The fluid flows from the second transverse bore 66 through the longitudinal bore 58 and from the longitudinal bore 58 on to the first transverse bore 62. The fluid enters the cooling chamber annular channel 48 at the first transverse bore 62. The fluid then flows from the cooling chamber annular channel 48 on the support disk 52 into the main cooling chamber 50. The fluid flows along or through the spring device 54 and then enters the piston 32 into its transfer channels 72. The fluid pressure in the main cooling chamber 50 opens the check valves 76 so that the fluid can enter the pressure chamber 46. From the pressure chamber 46, the fluid is then removed from the rotor assembly 4 via the first fluid connection 78.

In the illustrated embodiment, the permanent magnets 28 and the coil arrangement 100 lie axially within the area of the main cooling space 50. When the rotor assembly 4 is driven to machine a workpiece, heat is generated in the area of the permanent magnets 28 and the coil arrangement 100. The resulting heat can be efficiently be discharged via the fluid in the main cooling chamber 50. No further structures are necessary in the rotor 8 for this, in particular no further structures that could impair the stability of the rotor 8. In particular, no holes or channels for cooling are required in the casing of the rotor 8. Rather, it becomes Accommodation of the pull rod 30 and the spring device 54 required cavity in the rotor 8 used for cooling.

Figure 2 shows the tool spindle 2 from Figure 1, with the rotor assembly 4 of the tool spindle 2 in a release mode B. In release mode B, a tool holder (see reference numeral 90 in FIG. 1) can be released from the rotor 8 or attached to the rotor 8. The tool holder 90 and the clamping device 12 are not shown in FIG. 2.

In release mode B, the piston 32 with the pull rod 30 is moved towards the front opening area 14. The piston 32 has moved up to a piston stop 102. The pull rod 30 is in a release position LSt. In the release position LSt, the pull rod 30 engages less deeply in the rotary insert 34 than in the clamping position SSt, see FIG. 1. Furthermore, in the release mode B shown here, the check valves 76 are closed.

The rotor assembly 4 is brought into release mode B and a tool holder is replaced as described in the following example:

After machining a workpiece with the tool spindle 2, machining is stopped and the rotor assembly 4 is stopped. No more fluid is introduced into the cooling chamber 42 for cooling via the second fluid connection 80. Instead, fluid with high fluid pressure is introduced into the pressure chamber 46 via the first fluid connection 78. The fluid cannot flow through the piston 32 because the check valves 76 are closed. Due to the pressure built up in the pressure chamber 46, the piston 32 is moved against the spring force of the spring device 54 up to the piston stop 102. This also causes the pull rod 30, which is connected to the piston 32, to be displaced. The clamping sleeve 88 is moved with the pull rod 30, so that the clamping elements 82 can be moved radially inwards towards the axis of rotation DA (compare FIG. 1). This allows the tool holder 90 to emerge from the front opening area 14 removed and another tool holder inserted if necessary (not shown in detail).

In order to attach (clamp) the other tool holder to the rotor 8, the fluid pressure in the pressure chamber 46 is reduced, in particular down to the ambient pressure. The spring tension of the spring device 54 pushes the piston 32 back into the clamping position SSt (see FIG. 1), as a result of which the pull rod 30 also moves back and the tool holder is fastened to the rotor 8 by the clamping device 12. The tool change can be automated.

Figure 3 shows the support disk 52 of the rotor assembly 4 from Figure 1 alone. For better orientation, the axis of rotation DA of the rotor is shown here.

The support disk 52 is annular. The support disk 52 has four overflow channels 104 here. The overflow channels 104 are here arranged rotationally symmetrical to the axis of rotation DA of the rotor. The overflow channels 104 run radially and axially on the support disk 52. The axially extending sections of the overflow channels 104 are formed radially on the inside of an opening in the support disk 52. Alternatively or additionally, axially extending sections of the overflow channels 104 can be provided radially on the outside of the support disk 54 (not shown in more detail). The radially extending sections of the overflow channels 104 can point towards the spring device 54 in the installed state, see FIG. 1. Alternatively or additionally, radial sections of the overflow channels 104 pointing away from the spring device 54 can be provided (not shown in more detail). The fluid guidance on the support disk 54, in particular through the overflow channels 104 or radial distances between the support disk 54 and the pull rod 30 and / or the rotor 8, enables the fluid to flow in the cooling mode on the outside and inside along the plate spring package 55. 4a shows the check valve 76 in an enlarged detail from FIG. 1. The check valve 76 is here in the open position, which belongs to the cooling mode, in which the pull rod is in the clamping position.

The check valve 76 is designed as a ball check valve 106. The ball check valve 106 comprises a ball 108, a screw body 110 and a spring 111. The ball 108 is lifted from a seat 112 in the transfer channel 72 in the open position of the check valve 76. The screw body 110 has a screw transverse bore 114 and a longitudinal screw bore 116 through which the fluid can flow from the transfer channel 72 into the pressure chamber 46.

Figure 4b shows an enlarged detail from Figure 2, the check valve 76 in the closed position, which belongs to the release mode, in which the pull rod is brought into the release position. The ball 108 rests on the seat 112. The ball 108 closes the seat 112. No fluid can flow from the pressure chamber 46 via the transfer channel 72 into the cooling chamber (not shown in detail).

Figure 4c shows the screw body 110 in isolation in a perspective view (upper part of the image), in a side view (middle part of the image) and in a schematic longitudinal section (lower part of the image). One of the openings in the screw cross hole 114 can be seen in the upper and middle part of the picture. In the lower part of the picture, the screw transverse hole 114 and the screw longitudinal hole 116 are visible. The transverse screw hole 114 runs perpendicular to the longitudinal screw hole 116.

5a shows a part of the pull rod 30 in the area of the first transverse bore 62. In the pull rod 30 - as already explained above - the fluid guide 56 is formed with the longitudinal bore 58 and with the first transverse bore 62. The first transverse bore 62 runs perpendicular to the longitudinal bore 58. The longitudinal bore 58 extends exactly to the transverse bore 62. To the Towards the end assigned to the clamping device, the pull rod 30 is closed after the first transverse bore 62.

Figure 5b shows the area of the first transverse bore 62 of the tie rod 30. For better orientation, the axis of rotation DA of the rotor 8 is shown here.

The longitudinal bore 58 of the pull rod 30 lies on the axis of rotation DA. The first transverse bore 62 here runs radially to the axis of rotation DA of the rotor 8. The first transverse bore 62 is continuous here and opens into the cooling chamber annular channel 48 at two openings.

Figure 6 shows an enlarged view of the rotary insertion 34 of the rotor assembly 4. For better orientation, the axis of rotation DA of the rotor 8 is shown here. The pull rod 30 is shown here in the release position LSt.

The rotary insertion 34 has an insertion housing 118 and the connecting part 120. The insertion housing 118 is hollow inside. The connecting part 120 is partially arranged in the insertion housing 118. The connecting part 120 is also hollow inside. An end of the pull rod 30 assigned to the rotary insertion 34 is arranged in the connecting part 120. The pull rod 30 is axially movable relative to the connecting part 120. The connecting part 120 is firmly and fluid-tightly connected to the rotor 8 on the thread 24. The insertion housing 118 and the connecting part 120 are rotatable against each other. The insertion housing 118 and the connecting part 120 can be supported on one another via a pivot bearing 119. When the rotor 8 rotates, the connecting part 120 rotates together with the rotor 8. The insertion housing 118 basically does not rotate, but stands still.

The first fluid connection 78 and the second fluid connection 80 are located on the insertion housing 118. The first fluid connection 78 is designed here as a first connection bore 122. The second fluid connection 80 is second Connection hole 124 is formed. The connecting part 120 here has two first radial bores 126 and two second radial bores 128.

As previously described, the fluid guide 56 is formed in the pull rod 30. Of the fluid guide 56, the longitudinal bore 58, the second transverse bore 66 and a tie rod channel 129 running in the circumferential direction can be seen here.

An annular channel 130 is formed between the pull rod 30 and the connecting part 120. The annular channel 130 extends here from the first radial bores 126 in the connecting part 120 to the pressure chamber 46.

Furthermore, a pocket 132 is formed between the pull rod 30 and the connecting part 120. The pocket 132 is designed here as a circumferential groove 133. In the example shown, the pocket 132 is provided in the connecting part 120. The pocket 132 extends at least over the length that the pull rod 30 overcomes when moving from the clamping position SSt (see FIG. 1) to the release position LSt.

A first channel 134 running in the circumferential direction and a second channel 136 running in the circumferential direction are formed between the connecting part 120 and the insertion housing 118.

The pressure chamber 46 is fluidly connected to the first fluid connection 78. The connection here is as follows: The pressure chamber 46 is connected to the first radial bores 126 via the annular channel 130. The first radial bores 126 are in turn connected to the first fluid connection 78 via the first channel 134 running in the circumferential direction. The first circumferential channel 134 causes the connecting part 120 to be able to rotate relative to the insertion housing 118 without the fluidic connection between the pressure chamber 46 and the first fluid connection 78 being interrupted. The longitudinal bore 58 of the pull rod 30 is fluidly connected to the second fluid connection 80. The connection here is as follows: The longitudinal bore 58 is connected to the second radial bores 128 via the second transverse bore 66, the tie rod channel 129 running in the circumferential direction and via the pocket 132. The axial extension of the pocket 132 ensures that the fluidic connection is maintained regardless of the axial position of the pull rod 30 relative to the rotor 8 or the rotary insert 34. The second radial bores 128 are in turn connected to the second fluid connection 80 via the second channel 136 running in the circumferential direction. The second circumferential channel 136 causes the connecting part 120 to be able to rotate relative to the insertion housing 118 without the fluidic connection between the fluid guide 56 (and therefore the cooling space) and the second fluid connection 80 being interrupted.

Figure 7 shows part of the pull rod 30 with the piston 32. The pull rod 30 and the piston 32 are firmly connected to one another. Here the pull rod 30 and the piston 32 are integral with each other. On the tie rod 30, in particular the tie rod channel 129 running in the circumferential direction and the opening of the second transverse bore 66 can be seen in FIG.

In the present case, two circumferential piston grooves 138 are formed in the piston 32. Sealing elements and guide elements can be arranged in the circumferential piston grooves 138. Furthermore, two inlet channels 140 are formed on the first side 40 of the piston 32. The inlet channels 140 run radially to the pull rod 30. The inlet channels 140 begin on an outer wall 142 of the piston 32 and extend to the transfer channels 72. The fluid can here from the outside and inside of the plate spring package 55 (see Figure 1) into the Transfer channels 72 flow out.

8 shows a fluid diagram for carrying out an operating method according to the invention for the rotor assembly 4 according to the invention. In the fluid diagram shown, the cooling mode A is set up for the rotor assembly 4. Shown in the fluid diagram are the rotor assembly 4, a hydraulic pump 144, a directional control valve 146, a preferably adjustable pressure reducer 148, a fluid container 150 and a large number of lines 152 (only some of which are provided with a reference number for the sake of clarity). Of the rotor assembly 4, the rotor 8 and the rotary insert 34 are shown with the first fluid connection 78 and the second fluid connection 80.

The hydraulic pump 144 is here connected to an actuation 154, which actuates (drives) the hydraulic pump 144 by means of an electric motor. Fluid 156, here oil 158 (for example hydraulic oil), can be conveyed via the hydraulic pump 144. The hydraulic pump 144 provides the fluid with a release pressure LD of, for example, 170 bar. The hydraulic pump 144 can remove the fluid 156 from the fluid container 150 (not shown in detail). A fluid circuit can be set up in this way. The fluid can be cooled by a cooler, not shown. The cooler can be arranged, for example, between the fluid container 150 and the hydraulic pump 144 or between the pressure reducer 148 and the rotary insert 34.

The directional control valve 146 can be moved either into a first switching position a or a second switching position b. The cooling mode A is set up in the first switching position a. The release mode (not shown here) is set up in the second switching position b. In the variant shown here, the directional control valve 146 is biased into the first switching position a shown via a valve spring 160. By means of a parallel actuation 162 formed on the directional valve 146, the directional valve 146 can be moved into the second switching position b either via a muscle power actuation 164 or an electrical actuation 166. The electrical actuation 166 is used for automated operation of the tool spindle 2. The muscle power actuation 164 can be used for maintenance purposes or in the event of a malfunction.

The adjustable pressure reducer 148 here has a pressure relief valve 168. In the variant shown here, the pressure relief valve 168 is set so that the adjustable pressure reducer 148 on the hydraulic pump 144 provided release pressure LD of, for example, 170 bar is reduced to a cooling pressure KD of, for example, 10 bar.

In cooling mode A, the directional control valve 146 is in switching position a. The fluid 156 is conveyed to the directional valve 146 by means of the hydraulic pump 144 with the release pressure LD (here 170 bar). The fluid 156 then flows from the directional control valve 146 to the pressure reducer 148 and the release pressure LD is reduced to the cooling pressure KD (here 10 bar). The fluid 156 then flows further to the second fluid connection 80 at the cooling pressure KD and is used in the rotor assembly 4 for cooling. After the fluid 156 has flowed through the corresponding fluid spaces in the rotor assembly 4, the fluid 156 is discharged from the rotor assembly 4 via the first fluid connection 78. The fluid 156 flows to the directional control valve 146 and is directed there to the fluid container 150 and collected.

In the release mode (see FIG. 2), which is not shown in more detail in FIG. 8 but is also briefly described below, the directional control valve 146 is in the switching position b. The fluid 156 is conveyed to the directional valve 146 by means of the hydraulic pump 144 with the release pressure LD (here 170 bar). In the switching position b, the directional control valve 146 directs the fluid 156 from the hydraulic pump 144 directly to the first fluid connection 78, so that the release pressure LD also builds up in the pressure chamber 46. This opens the clamping device 12 in the rotor assembly 4, see also Figure 2.

Figure 9 shows a highly abstracted representation of a machine tool 170. A tool 172, for example a grinding wheel, is held on a tool spindle 2 according to the invention via a tool holder 90. A workpiece 174 to be machined, for example a gear, can be moved relative to the tool spindle 2. The tool spindle 2 and the workpiece 174 can also be pivotable relative to one another, compare pivot point SP of the tool spindle 2. In particular, the workpiece can be arranged on a workpiece table (not shown in detail) or on a Workpiece spindle 176 can be held. In the latter case, the workpiece 174 can also be rotated about a workpiece axis WA.

Reference character list

2 tool spindles

4 rotor assembly

6 stator assembly

8 (hollow) rotor

10 actuation device

12 clamping device

14 front opening area

16 rear opening area

18 recording

20 lead

22 inner cones

24 threads

26 outside of the rotor

28 permanent magnet

30 pull rod

32 pistons

34 Turning Introduction

36 outer wall of the tie rod

38 inner wall of the rotor

40 first side (of the piston)

42 cold room

44 second side (of the piston)

46 pressure room

48 cold room ring channel

50 main cold room

52 support disk

54 spring device 55 disc spring package

56 fluid guidance

58 longitudinal bore

60 first mouth

62 first cross hole

64 second mouth

66 second cross hole

68 cold room side section of the pull rod

70 pressure chamber side section of the tie rod

71 middle section of the pull rod

72 transfer channel

74 screw bodies

76 check valve

78 first fluid connection

80 second fluid connection

82 clamping elements

88 adapter sleeve

90 tool holders

94 taper shaft

98 spindle housings

100 coil arrangement

102 piston stop

104 transfer channel

106 ball check valve

108 ball

110 screw bodies

111 feather

112 seat

114 screw cross hole

116 screw longitudinal hole

118 introductory housing

119 Pivot bearing

120 connecting part 122 first connection hole

124 second connection hole

126 first radial bore

128 second radial bore

129 circumferential tie rod channel

130 ring channel

132 bag

133 circumferential groove

134 first circumferential channel

136 second circumferential channel

138 circumferential piston groove

140 inlet channel

142 outer wall (of the piston)

144 hydraulic pump

146 directional control valve

148 pressure reducer

150 fluid containers

152 line

154 actuation

156 Fluid

158 oil

160 valve spring

162 parallel operation

164 muscle force activity

166 electrical actuation

168 pressure relief valve

170 machine tool

172 tool

174 workpiece

176 processing table a first switching position

A Cooling mode b Second switching position B Release mode

DA axis of rotation

KD cooling pressure

LD release pressure LSt release position

SP pivot point

SSt clamping position

VR. Travel direction

WA workpiece axis

Claims

Claims Rotor assembly group (4) for a tool spindle (2), comprising

- a hollow rotor (8),

- an actuating device (10) for actuating a clamping device (12) for releasably attaching a tool holder (90) to the rotor (8), the actuating device (10) having a pull rod (30) and a piston rigidly coupled to the pull rod (30). (32), which are mounted together to be movable along a travel direction (VR) in the hollow rotor (8), in particular wherein the travel direction (VR) corresponds to the direction of an axis of rotation (DA) of the rotor (8), the tie rod (30) is biased into a clamping position (SSt) by a spring device (54) and can be brought into a release position (LSt) against the biasing force of the spring device (54) by applying fluid pressure to the piston (32), the piston (32) being in the rotor (8) separates a pressure chamber (46) and a cooling chamber (42) from one another, at least one check valve (76) being provided in the piston (8), which prevents fluid (156) from flowing from the cooling chamber (42) into the pressure chamber (46) allows and prevents fluid (156) from flowing out of the pressure chamber (46) into the cooling chamber (42), a first fluid connection (78) being provided which is fluidly connected to the pressure chamber (46), in which The pull rod (30) has a fluid guide (56) through which fluid (156) can be introduced into the cooling space (42), and wherein a second fluid connection (80) is provided, which is fluidly connected to the fluid guide (56). Rotor assembly (4) according to claim 1, characterized in that the spring device (54) is arranged in the cooling space (42) and is in particular designed as a plate spring package (55). Rotor assembly (4) according to claim 1 or 2, characterized in that the spring device (54) is supported at one end via a support disk (52) on the rotor (8) and at the other end on the piston (32). Rotor assembly (4) according to claim 3, characterized in that the fluid guide (56) opens into the cooling space (42) beyond the support disk (52) as viewed from the spring device (54). Rotor assembly (4) according to claim 3 or 4, characterized in that the support disk (52) has at least one overflow channel (104) for the fluid, preferably has a plurality of overflow channels (104) arranged rotationally symmetrically to an axis of rotation (DA) of the rotor (8). . Rotor assembly (4) according to one of the preceding claims, characterized in that a plurality of check valves (76) are provided in the piston (32), which are preferably arranged rotationally symmetrically to an axis of rotation (DA) of the rotor (8). Rotor assembly (4) according to one of the preceding claims, characterized in that the fluid guide (56) in the tie rod (30) has a longitudinal bore (58) along an axis of rotation (DA) of the rotor (8) and a first transverse bore (62), which the longitudinal bore (58) fluidly connects to the cooling chamber (42), preferably wherein the first transverse bore (62) runs radially to the axis of rotation (DA). Rotor assembly group (4) according to claim 7, characterized in that the longitudinal bore (58) is closed at an end remote from the pressure chamber. Rotor assembly (4) according to one of the preceding claims, characterized in that the piston (32) and the tie rod (30) are integral with one another. Rotor assembly (4) according to one of the preceding claims, characterized in that the actuating device (10) further comprises a rotary insertion (34) with an insertion housing (118) and a connecting part (120), the insertion housing (118) and the connecting part (120 ) are rotatable relative to one another, wherein the first fluid port (78) and the second fluid port (80) are formed on the insertion housing (118), and wherein the connecting part (120) fluidly connects the first fluid port (78) to the pressure chamber (46) and fluidly connects the second fluid connection (80) to the fluid guide (56) in the pull rod (30). Rotor assembly (4) according to claim 10, characterized in that the tie rod (30) extends into the connecting part (120). Rotor assembly (4) according to claim 11, characterized in that there is an annular channel between the tie rod (30) and the connecting part (120). (130) is formed, via which the first fluid connection (78) is fluidly connected to the pressure chamber (46). Rotor assembly (4) according to claim 12, characterized in that the annular channel (130) is fluidly connected to the first fluid connection (78) on the insertion housing (118) via at least one first radial bore (126) in the connecting part (120), with between a first channel (134) running in the circumferential direction is formed in the connecting part (120) and the insertion housing (118), which is fluidly connected to the at least one first radial bore (126) and the first fluid connection (78). Rotor assembly (4) according to one of claims 11 to 13, characterized in that the connecting part (120) is fixed to the rotor (8), that a pocket (132) is formed between the pull rod (30) and the connecting part (120), which is fluidly connected to the second fluid connection (80) via a second radial bore (128) in the connecting part (120), that the pull rod (30) has a second transverse bore (66) which has a longitudinal bore (58) of the fluid guide (56). the pull rod (30) fluidly connects to the pocket (132), and that the pocket (132) extends along the travel direction (VR) to such an extent that the longitudinal bore (58) from the clamping position (SSt) to the release position (LSt) remains fluidly connected to the second fluid connection (80) via the second transverse bore (66), the pocket (132) and the second radial bore (128), in particular wherein the pocket (132) is formed in the connecting part (120), preferably as a circumferential one Groove (133).

15. Rotor assembly group (4) according to claim 14, characterized in that between the connecting part (120) and the insertion housing (118) a second circumferentially running channel (136) is formed, which is connected to the at least one second radial bore (128). and is fluidly connected to the second fluid connection (80).

16. Rotor assembly (4) according to one of the preceding claims, characterized in that permanent magnets (28) are attached to the rotor (8), the permanent magnets (28) being at least partially, preferably completely, in the area of the longitudinal extent of the cooling space (42). are arranged.

17. Rotor assembly (4) according to one of the preceding claims, characterized in that the rotor assembly (4) has the clamping device (12), preferably wherein the clamping device (12) has a plurality of clamping elements (82), particularly preferably wherein the clamping elements (82) are arranged rotationally symmetrically to an axis of rotation (DA) of the rotor (8).

18. Tool spindle (2) comprising a rotor assembly (4) according to one of the preceding claims and a stator assembly (6) with a spindle housing (98) in which the rotor (8) is rotatably mounted, preferably in the spindle housing (98). Coil arrangement (100) is provided for driving the rotor (8).

19. Actuating device (10) for a rotor assembly (4) of a tool spindle (2), in particular for a rotor assembly (4) according to one of claims 1 to 17, having a pull rod (30) which has a longitudinal bore (58) as a fluid guide (56 ), and a piston (32) which is rigidly attached to the Pull rod (30) is coupled and sits on the pull rod (30), so that the pull rod (30) has a section (68) on the refrigerator side on a first side (40) of the piston (32) and on a section (68) opposite the first side (40), second side (44) of the piston (32) has a section (70) on the pressure chamber side, the fluid guide (56) having at least one first opening (60) in the section (68) on the cooling chamber side and at least one second opening (64) in the section (70) on the pressure chamber side ), in particular wherein the at least one first mouth (60) is formed by a first transverse bore (62) and the at least one second mouth (64) is formed by a second transverse bore (66), and wherein in the piston (32) there is at least one check valve ( 76) is provided, via which the two sides (40, 44) of the piston (32) are fluidly connected, the check valve (76) opening at a higher pressure on the first side (40) than on the second side (44). and blocks at a higher pressure on the second side (44) than on the first side (40). Operating method for a rotor assembly (4) according to one of claims 1 to 17 or a tool spindle (2) according to claim 18, wherein in a cooling mode (A) fluid (156), in particular oil (158), is fed in through the second fluid connection (80). the fluid guide (56) is introduced so that it flows through the cooling chamber (42), through which at least one check valve (76) flows into the pressure chamber (46) and is discharged through the first fluid connection (78), and wherein in a release mode (B ) fluid (156) is introduced into the pressure chamber (46) through the first fluid connection (78), so that a release pressure (LD) is built up in the pressure chamber (46), through which the pull rod (30) counteracts the action of the spring device (54 ) is brought into the release position (LSt) by means of the piston (32). Operating method according to claim 20, characterized in that the fluid (156) is provided with at least the release pressure (LD), and that the fluid (156) in the cooling mode (A) through a pressure reducer (148) to the second fluid connection (80) is directed.