DE102019203078A1 - Motor spindle with differently adjusted fiber-reinforced plastic materials and method for controlling a motor spindle - Google Patents

Abstract

The invention relates to a motor spindle (11) for driving a tool (15) clamped directly or held in a tool holder (13), with: - a spindle shaft (19) driven by means of a drive unit (17), - a tool interface (21) for releasable rotationally fixed coupling of the tool holder (13) to the spindle shaft (19), - a bearing device (23) for rotatably mounting the spindle shaft (19), - a housing (25) by the spindle shaft (19), the bearing device (23) and the Drive unit (17) are added. In order to provide an improved motor spindle (11), it has at least two fiber-reinforced plastic materials that are set differently in terms of stiffness, thermal conductivity and / or thermal expansion coefficient.

Description

Field of invention

The invention relates to a motor spindle for driving a tool or a tool held in a tool holder, with a spindle shaft driven by means of a drive unit, a tool interface for the detachable non-rotatable coupling of the tool holder to the spindle shaft, a bearing device for the rotatable bearing of the spindle shaft and a housing in which the Spindle shaft, the bearing device and the drive unit are included and a method for regulating such a motor spindle.

State of the art

Motor spindles for driving a tool held in a tool holder are known. These are usually used for machining, in particular machining, of materials. For such processing, comparatively high speeds and frequent acceleration and braking processes are required. In addition, the driven tool may also have to be changed several times during the machining of a workpiece. As a result, alternating thermal loads and vibration excitations occur on generic motor spindles in the course of a machining process. Waste heat from the drive unit and frictional losses of the bearing device for mounting the spindle shaft and possibly process heat on the tool occur as heat sources. This heat can be dissipated, for example, by means of compressed air and / or water cooling. Due to the high speeds, dynamic loads such as centrifugal forces occur, in particular on the bearing device, which, in addition to the thermal load, can also lead to changes in operating parameters of the motor spindle. It is known to use a fiber-reinforced plastic material for motor spindles, which is also known as such in principle. The EP 3 069 848 A1 shows, for example, from a very distant technical field of the production of sporting goods, a method for molding a fiber-reinforced composite material structure with the following steps: providing a preform which has at least one layer and an adjoining second layer, each of the layers having a resin matrix and fibers and wherein a direction of the fibers of the first layer differs from a direction of the fibers of the subsequent layer; a helical winding of the preform around a core from a first end region of the core to a second end region of the core and / or from the second end region to the first end region so that the direction of the fibers in the first layer are relative to an axial direction of the core Increase an efficiency. The preparation and winding of the layers is repeated until a three-dimensional specific structure is defined. This is optionally pressurized and solidified by a heat treatment cycle. A hollow shaft can be obtained by removing the core. The DE 197 26 341 A1 relates to a shaft of a motor-driven spindle with a rotor connected to it, the shaft being made of reinforced plastic (composite material) and the rotor being integrated into the shaft material. The rotor is wrapped in reinforced plastic material. The rotor can have grooves in which the winding engages. The reinforced plastic is preferably a CFRP material. From the DE 40 09 461 A1 a spindle for a machine tool is known. This comprises a cylindrical element for receiving the shank of a tool. It is made by winding carbon or glass fibers, whereby the wound fiber is impregnated with a thermosetting resin. After the resin has hardened, a protective coating layer is applied to the outer surface of the cylindrical member. With this structure, it is possible to reduce the weight and the linear thermal expansion coefficient of the spindle and thereby improve the machining accuracy.

Presentation of the invention

The object of the invention is to provide an improved motor spindle for driving a tool held in a tool holder, in particular to improve the service life of the motor spindle, to facilitate a tool change, to reduce the size of the motor spindle, to improve cooling of the motor spindle and / or higher speeds to enable.

In the case of a motor spindle for driving a tool held in a tool holder according to the preamble of claim 1, the object is achieved in that the motor spindle has at least two fiber-reinforced plastic materials that are set differently in terms of rigidity, heat conductivity and / or a coefficient of thermal expansion. It has been found that fiber-reinforced plastic materials can be adjusted in a comparatively large range in terms of the properties of elasticity and / or stiffness, thermal conductivity properties and the coefficient of thermal expansion due to the composition of the plastic material and the fibers. Particularly in comparison to steel, advantageous material properties can be provided for the motor spindle exactly where they affect the performance of the motor spindle, in particular a service life, an acceleration and braking behavior, a vibration behavior and / or a speed positively influence. In addition, it was found that the different setting of the plastic materials is also possible in an integrally connected component. It is therefore conceivable to adapt an integrally connected component, such as the spindle shaft of the motor spindle, to technical requirements in certain areas, in particular elasticities, in order to have a positive influence on the vibration behavior. The different setting of the fiber-reinforced plastic materials can also be done by a combination of two components, for example in the form of a spacer ring combined with the spindle shaft and / or the like. The setting of the fiber-reinforced plastic material can in particular take place through a combination of different layers, an alignment of fibers and / or the choice of fibers. In particular, it is thereby possible to set a coefficient of thermal expansion of zero or possibly even less than zero. It was also found that these specific properties can also be used to implement control loops that respond to heat. A fiber-reinforced plastic material can in principle be understood to mean a resin and / or substrate, in particular thermosetting, by means of which different layers of fibers are impregnated and cured. In particular, the fibers can be carbon fibers, that is to say a so-called CFRP material. This advantageous combination of differently adjusted fiber-reinforced plastic materials enables speeds of over 30,000, preferably up to 60,000 revolutions per minute to be achieved, with accelerations and decelerations being possible every second. In addition, the result is a comparatively small motor spindle, and any contours of the motor spindle which interfere with the machining of the workpiece can be reduced to a minimum. The reduction of the interfering contour results from the fact that, due to the advantageous fiber-reinforced plastic material (s), in particular CFRP materials, in particular with a thermal coefficient of thermal expansion of zero, the motor spindle, in particular a housing of the motor spindle, can be held at any point without the precision of the Machine to deteriorate. Steel motor spindles known from the prior art are connected to a manipulation device as close as possible to the tool in order to minimize thermally induced offsets, in particular axial offsets, on the tool and thus machining errors. This manipulation device inevitably represents an interfering contour for the machining process. The motor spindle according to the invention minimizes this interfering contour, since it can be connected to the manipulation device at any point, possibly also at an end opposite the tool, without producing thermal machining errors. This is possible because, in particular, by using a fiber-reinforced plastic material with a thermal expansion coefficient of zero or close to zero, the connection between temperature and geometry changes is at least largely eliminated. A novel motor spindle according to the invention can therefore be held on the side facing away from the tool, so that a holding structure of the manipulation device protrudes considerably less into a machining area and therefore interferes less during machining. The new motor spindle can therefore be attached to a manipulation device at any axial distance from the tool without loss of precision. During operation, there is an axial distance between the processing point or the tool and the said fastening point with a minimal interference contour of more than 20%, in particular more than 50%, in particular more than 80%, in particular a total length of the housing, of the novel motor spindle. In addition, the motor spindle itself has a comparatively low weight, so that it can also be positioned more easily and more precisely relative to the workpiece by means of an automated manipulation device.

Process forces can therefore be absorbed very well, with a high machining quality in terms of position, shape tolerances, concentricity and low displacement of the tool relative to a desired position, as well as high rigidity with a large speed range, which enable a high metal removal rate and high productivity .

The precision, as one of the most important criteria for motor spindles, can be significantly improved. Above all, the repeatability is significantly improved, so that the motor spindle according to the invention, in particular with changing temperatures, delivers reproducible milling results at a consistently good level. In comparison to motor spindles made of steel, which expand very strongly under the influence of heat, the repeatability is enormously improved. In addition, an effort known and carried out from the prior art in steel motor spindles for generating the repeat accuracy can be reduced to zero, at least to a minimum, by providing the differently adjusted fiber-reinforced plastic materials. The advantageous embodiment is already structurally specified in the differently adjusted fiber-reinforced plastic materials, in particular any software control circuits that may be required are not required or can be reduced to a minimum. Rather, it is even possible using the structurally specified hardware in the form of fiber-reinforced Plastic materials to integrate control loops directly into the motor spindle. This means that, for example, a laminate structure of the motor spindle is designed in such a way that it no longer expands in the axial direction. In particular, a coefficient of thermal expansion of zero can be provided in the fiber-reinforced plastic materials. This makes it possible to dispense with virtually all compensation systems, so that the motor spindle can not only be manufactured more cheaply, but is also more precise at the same time. The rapid acceleration of the motor spindle as a whole, as well as the start-up and shut-down, result in particularly short cycle times. Together with the possibly achievable higher speeds with the same precision, a higher material removal per time, that is a higher metal removal rate, is possible. This is achieved by a higher rigidity of the motor spindle with a reduced weight at the same time. In particular, the fiber-reinforced plastic materials, in particular CFRP materials, have up to 100 times better damping properties compared to conventional materials such as steel, which results in significantly higher dynamic stiffnesses. In particular, critical frequencies can be shifted into a non-disruptive area. This also enables a rigid mounting of the motor spindle which can be manufactured or manufactured from the fiber-reinforced plastic material. A floating bearing, which may otherwise be required and which is known in the prior art to compensate for thermal expansions, can be dispensed with. A possibly required sliding fit inside the motor spindle can therefore be dispensed with. The motor spindle is therefore mounted without a sliding seat or loose bearing by means of a bearing device. In addition, it is known to use the differently adjusted fiber-reinforced plastic materials to adapt the motor spindle at least in certain areas so that it adapts to the requirements of the bearing devices due to centrifugal forces and / or temperature influences. In particular, an expansion caused by centrifugal force can be adapted in such a way that a press fit of roller bearings pressed onto the spindle shaft, in particular ball bearings, has a sufficient holding force even at high speeds. Slipping through of the inner bearing rings due to an expansion caused by centrifugal force can thus be reliably prevented. An undesired lifting of the bearing from the spindle shaft at high speeds is thus prevented. In all operating conditions, whether standstill or maximum speed, there is sufficient surface pressure between the bearings or bearing inner rings and the spindle shaft. In comparison to a bearing on steel shafts, a loss of surface pressure can be prevented by an expansion of the centrifugal force. This enables bearings to be placed directly on the spindle shaft, it being possible to dispense with a steel sleeve arranged radially between the bearing and the spindle shaft. The bearing device is thus formed radially without an intermediate sleeve. In addition, the differently adjusted fiber-reinforced plastic materials can provide a very lightweight and high-strength motor spindle. As a result, speeds of up to 30,000, preferably up to 60,000 revolutions per minute can be achieved, with acceleration and deceleration being possible every second. These speeds can be achieved, for example, with bearings that are lubricated for life and a bearing bore diameter of 40 mm in a rigid position. For other bearing designs, there are other speed ranges which, compared to known concepts, enable significantly higher speeds without any loss of quality. This has decisive advantages for the dynamics and energy efficiency of a cutting machine having the motor spindle.

In a preferred embodiment it is provided that a first of the fiber-reinforced plastic materials is arranged between the storage device and a cooling device. This first of the fiber-reinforced plastic materials has a direction-dependent thermal conductivity that is increased in one direction between the storage device and the cooling device. The direction between the storage device and the cooling device can in particular be understood as an imaginary direct connection between the storage device and the cooling device. However, it can also be understood to mean a curved or otherwise configured heat conduction path between the bearing device and the cooling device. In a further direction running at an angle to the direction, the first fiber-reinforced plastic material has a comparatively lower thermal conductivity. As a result, a heat flow from the storage device to the cooling device can be improved and a desired temperature control of the storage device can thus be achieved.

Alternatively or additionally, it is possible in this context for the first fiber-reinforced plastic material to have aligned heat-conducting fibers. It has been found that a directional thermal conductivity can be set by means of the fibers, which are required in any case for fiber-reinforced plastic materials. This can be expanded to values a multiple of conventional materials such as steel, in particular up to a factor of 30. In particular, carbon fibers based on pitch with a high thermal conductivity of 100-600 W / mK, in particular 300 to 600 W / mK, have been found to be particularly suitable. The first fiber-reinforced plastic material therefore has, in particular, pitch fibers.

Alternatively or additionally, it is also conceivable that the heat conducting fibers run essentially between the bearing device and the cooling device. This makes it possible for each individual one of the heat-conducting fibers to form a partial heat-conducting path, which add up to form a heat-conducting path that runs from the bearing device to the cooling device.

It is preferably provided that a bearing plate of the bearing device has the first fiber-reinforced plastic material. The end shield of the bearing device therefore preferably has the aligned heat-conducting fibers and thus the advantageous heat-conducting path. The end shield can be arranged in direct, heat-transferring contact with bearing outer rings of bearings of the bearing device. In this way, heat generated in the bearings, in particular frictional heat, can be transferred directly from the respective bearing outer ring to the end shield and from there to the cooling device via the aligned heat-conducting fibers. For this purpose, the cooling device can likewise be in heat-transferring contact contact with a side of the end shield opposite the outer bearing rings. In particular, it is conceivable that the radially outer side of the end shield is arranged adjacent to a fluid path of the cooling device that carries a cooling medium, for example water. As a result, the heat generated in the outer ring of the respective bearing can be transferred to the heat-carrying fluid, in particular the water, directly via the end shield, ie in particular the aligned heat-conducting fibers. This results in particularly good cooling of the storage device.

In a further possible embodiment, a spacer sleeve of the bearing device has the first fiber-reinforced plastic material. For spacing purposes, the spacer sleeve can be in heat-transferring contact contact with bearing inner rings of two bearings of the bearing device. The inner bearing rings are preferably fixed directly on the motor spindle, without loose bearings and / or radially without intermediate sleeves, in particular there by means of a press fit. Due to the heat-transferring contact contact, the frictional heat that occurs can be transferred to and from the spacer sleeve. In particular, a heat transfer medium, in particular compressed air, can be applied to the spacer sleeve for this purpose. The heat absorbed by means of the spacer sleeve can therefore be passed on by means of the compressed air and finally transported away. In particular, a surface of the spacer sleeve has a delimitation of a fluid path guiding the heat-conducting medium or the compressed air. The direct wetting means that the heat can be dissipated even better. As a result, the inner bearing rings of the bearing device can also be temperature-controlled or cooled very well.

It is particularly preferably provided that the heat conducting fibers are cut on a surface of the first fiber-reinforced plastic material or at least run towards this surface. By running towards the surface, it can be understood that the fibers end just below the surface. In the case of direct incision, however, it can also be that these protrude from the surface or are directly exposed on it. As a result, particularly good heat transport or transition from the surface to the heat-conducting medium and / or by means of the heat-transferring contact contact described above can take place.

According to a further additional or alternative embodiment, the spacer sleeve can have an indentation in which the heat-conducting fibers end, the indentation being able to be acted upon with a heat-conducting medium in order to carry away heat. It is conceivable to manufacture the spacer sleeve in such a way that the heat conducting fibers run in a longitudinal direction of the motor spindle, in particular in a longitudinal direction of the spindle shaft. As a result, they basically run from a first inner bearing ring to a second inner bearing ring, the spacer sleeve being in heat-transferring contact with the inner rings at both ends and at the same time spacing them apart, in particular transmitting an axial bearing preload force. By means of the indentation, which can be produced, for example, by removing material, the heat-conducting fibers can be exposed in a simple manner. As a result, heat can be transported on both sides in the spacer sleeve from the respective inner bearing ring to a central region of the spacer sleeve. The heat is transported from the two ends of the spacer sleeve to a center of the spacer sleeve which has the indentation. In order to finally transport the heat away, the indentation can be acted upon by the heat-conducting medium, in particular pressure. This construction can also advantageously be used in the case of cooling devices that are already customary, in which compressed air is also introduced between two bearings. In summary, the advantageous heat-conducting fibers or the first fiber-reinforced plastic material with the thermal conductivity set depending on the direction do not have to be provided on the entire motor spindle. Rather, the advantages can already be achieved in that the first fiber-reinforced plastic material is specifically provided on the end shield and / or the bearing sleeve, with a conventional fiber-reinforced plastic material known as such being used on the rest of the motor spindle, in particular a CFRP material.

In a likewise possible embodiment, a second of the fiber-reinforced plastic materials is arranged at the tool interface and / or a fifth of the fiber-reinforced plastic materials is arranged on the bearing device, each of which, in particular individually adapted, has a comparatively higher rigidity in a longitudinal direction of the motor spindle than in a circumferential direction of the motor spindle . The tool interface is usually designed so that the motor spindle encompasses the circumference of the tool holder in the assembled state. This creates a self-locking that must be overcome when changing tools, i.e. when removing the tool holder from the spindle shaft. As a result of the rigidity being reduced in the circumferential direction, a surface pressure that occurs during self-locking and thus the ejection force that is required to eject the tool holder can be reduced. A desired centering of the tool holder during coupling, that is, during operation of the motor spindle, is not impaired. In the opposite case, i.e. in the case of the bearings that are located radially outside the spindle shaft, a centrifugal force-related expansion of the spindle shaft can be increased, in particular it can be selected so that a surface pressure between the bearings of the bearing device placed on the spindle shaft and the spindle shaft despite centrifugal force-related expansion of the Bearing or inner rings of the bearing remains as constant as possible, is corrected at least as a result of the speed in such a way that lifting of the bearing from the spindle shaft can be reliably avoided. In this case it is therefore possible to combine the second fiber-reinforced plastic material with the fifth fiber-reinforced plastic material in just one component. With only one integral component, which has two differently adjusted fiber-reinforced plastic materials, the two advantages described above, i.e. easier ejection of the tool holder and preventing the inner rings of the bearing of the bearing device from lifting off, can be achieved. In addition, it is possible to design the entire spindle shaft so that it also has a thermal expansion coefficient of zero or at least almost zero, so that a third advantage, namely a temperature-independent precision or relative position of the tool to the workpiece, can be achieved. In this case, the differently adjusted fiber-reinforced plastic materials of the preferably integral spindle shaft can achieve three advantages. Alternatively, at least one of the fiber-reinforced plastic material can also be provided for the different tasks described at two points of the integral component.

It is preferably provided that a shaft cone of the spindle shaft that interacts with the tool holder is the second fiber-reinforced plastic material 45 having. The shaft cone is usually used to receive and center a hollow tapered shank of the tool holder 13 in a self-inhibited, surface contact. As described above, a surface pressure that occurs can be avoided by the above-described setting of the second fiber-reinforced plastic material 45 can be reduced, which enables easier ejection of the tool holder and thus the tool from the motor spindle.

In an alternative that is also possible, it is conceivable that the spindle shaft has a flat contact that interacts with the tool holder, the flat contact and the shaft cone acting as a double fit for the tool holder, with a clamping force for clamping the tool holder being proportionate 90 to 70 to 10 to 30th , preferably about 80 to 20 distributed on the plane contact with the wave cone. It is possible for the tool interface to be designed as a standard part, with the shaft cone and the plane contact usually striking. When the tool holder is inserted into the spindle shaft, the surface pressure for centering is built up within the shaft cone, which in turn can be limited by means of the plane contact. When the tool holder is introduced into the motor spindle, forces act in a longitudinal direction of the spindle shaft or motor spindle. With a standard-compliant (DIN 69063) steel spindle, the force distribution from the face to the cone is, depending on the location of the manufacturing tolerances, from only 60 to 35 to 40 to 65. The portion that occurs on the shaft cone causes the ejection force required in the opposite direction. It can be seen that by reducing the proportion from 65 to 40 to 10 to 30, preferably 20, a significant reduction in the ejection force is possible. As a result, both an ejection device provided for ejecting the tool holder and a clamping device provided for clamping the tool can be designed to be significantly weaker and therefore smaller. The ejection device can therefore have comparatively smaller means for ejecting and / or clamping the tool holder. In particular, it can be a linear drive, for example a magnetically actuated, pneumatically actuated and / or hydraulically actuated linear drive for applying the force required to the tool holder during ejection and / or clamping.

An additional embodiment provides that a clamping tube of the tool interface has a third of the fiber-reinforced plastic materials, the third fiber-reinforced plastic material having a comparatively high internal damping. When operating the motor spindle are based on the tool Vibration stimulating vibrations or pulsating forces. When the tool interface is clamped, these also act on the clamping tube. Due to the comparatively high internal damping, the longitudinal and / or radial vibrations of the clamping tube can be reduced to a minimum. In particular, corresponding resonance frequencies can be increased, preferably shifted into a non-critical range. This effect occurs through the combination of the differently adjusted fiber-reinforced plastic materials, with the comparatively high internal damping only having to be provided on the components that are particularly susceptible to vibration. The comparatively high internal damping can, however, also be provided in areas at other points on the motor spindle that are particularly susceptible to vibration.

A preferred embodiment is designed such that a fourth of the fiber-reinforced plastic materials has a coefficient of thermal expansion that differs from that of a further component of the motor spindle and / or an intermediate ring of the bearing device has the fourth fiber-reinforced plastic material. In particular, the intermediate ring has a coefficient of expansion, in particular with a coefficient of thermal expansion of zero or at least close to zero. This results in a different thermal expansion of the spindle shaft and the intermediate ring placed on it. This enables a temperature-dependent spacing of two roller bearings, in particular ball bearings, in particular two bearing inner rings of the two ball bearings of the drive unit 17th . For this purpose, the intermediate ring is preferably in force-transmitting contact contact with the inner rings of the ball bearings of the bearing device. It has been found that a kinematic displacement of rolling elements and / or bearing rings of the bearings of the bearing devices occurring at high speeds can shift or increase a preload force of the bearings into an undesired range. This results in increased friction and consequently increased heating of the bearings. This heating is transferred to the spacer sleeve, so that it is smaller than the spindle shaft. This automatically reduces the bearing preload and thus the amount of heat generated. The specially adjusted fourth fiber-reinforced plastic material in combination with the fiber-reinforced plastic material of the spindle shaft thus forms a control loop for adjusting the axial preload of the bearings of the bearing device. This results in a speed-independent or speed-independent mounting of the spindle shaft, which leads to a longer service life of the bearing device due to the reduced friction that can be achieved therewith. In principle, the fourth fiber-reinforced plastic material can be provided on at least any component of the bearing device located in the force flow of the axial preload force, in particular on a rotor carrier arranged between the bearing pairs, on the end shields, on the spindle shaft and / or on the inner and / or outer intermediate ring .

Alternatively or additionally, it is possible that the fourth fiber-reinforced plastic material and / or the intermediate ring is arranged between two bearings of the bearing device, whereby an axial preload force can be transmitted to the bearings via these and a heat flow can be introduced into the intermediate ring from the bearings, whereby a An increase in temperature of the intermediate ring causes a reduction in the axial preload force. As a result, a control loop is formed, the axial preload force representing the control variable of the control loop. The bearings themselves serve as measuring elements, which indirectly absorb or measure the axial preload force via the increased friction and the resulting increased heat flow. The intermediate ring serves as a controller and as an actuator at the same time. Due to the negative thermal expansion coefficient, this reduces the axial preload force when the temperature rises. The speed and thus the kinematic displacement, which increases the axial pre-tensioning force, acts as a disturbance variable in this control loop. Other disturbance variables can also be changes in the length of spacer sleeves, shafts or other parts that are in the force flow of the bearings. The disturbance variables are counteracted by the use of reinforced plastic materials, which at the same time leads to a desired temperature reduction at the bearings.

It is therefore alternatively or additionally possible that the motor spindle has a control circuit for regulating the axial preload force, the fourth fiber-reinforced plastic material being acted upon by the axial preload force and, in combination with the further component, forms a measuring element and / or actuator of the control circuit. The control loop is an integral part of the components of the motor spindle, which enables a motor spindle that is more simply constructed and operable.

The object is also achieved by a method for regulating a storage device, in particular a storage device of a motor spindle described above for driving a tool that is directly clamped or held in a tool holder. First, a heat flow that occurs during operation is generated in a bearing device of the motor spindle. The heat flow is then introduced into an intermediate ring of the bearing device. The intermediate ring is shortened by means of a temperature increase generated by the introduced heat flow. In addition, an axial preload force of the bearing device is reduced by shortening the Intermediate ring. A negative feedback and thus a control loop for setting the axial preload force can be represented by the method. As previously described, this can be done by combining two differently adjusted fiber-reinforced plastic materials. A kinematic displacement of rolling elements and / or bearing rings of bearings of the bearing device causes an increase in the axial preload force. This increases the heat flow and the temperature of the intermediate ring increases. This reacts to the temperature increase by reducing its axial length, in particular relative to a corresponding axial length of the spindle shaft on which it is applied. This shortens a distance between the inner rings of the bearings of the bearing device, as a result of which the axial preload force is reduced. The lowering of the axial preload force caused by the contraction of the intermediate ring cannot prevent the kinematic displacement, but creates a free space that the corresponding bearing or the rolling elements can occupy, whereby this advantageously counteracts an otherwise forced tension and the associated increase in bearing friction can be. The control loop implemented in this way can be viewed as a proportional controller, with a control deviation remaining, however, compared to the non-controlled state, significantly lower temperatures and / or a significantly lower increase in the axial preload force despite very high speeds of up to 30,000, in particular 30,000 to 60,000, in particular about 60,000 revolutions per minute are possible. The regulation means that a sliding seat can be dispensed with and all bearings can be adjusted rigidly. With a bearing bore diameter of 40mm and bearings that are grease-lubricated for life in a rigid position, speeds of 40,000 rpm and more can be achieved, for example. In addition, the time behavior of the controller implemented in this way can be influenced by applying a cooling medium to the intermediate ring. The intermediate ring is therefore optionally cooled. The better the cooling of the intermediate ring, the shorter the time behavior of the heat flow from the bearings in the intermediate rings, which can be understood as a measuring section. As a result, the bearing device can be designed particularly advantageously without loose bearings and radially without intermediate sleeves.

The features listed individually in the patent claims can be combined with one another in a technologically sensible manner and can be supplemented by explanatory facts from the description and by details from the figures, further embodiment variants of the invention being shown. Further advantages emerge from the subclaims and the following description of a preferred exemplary embodiment.

Figure list

• 1 eine Längsschnittansicht einer teilweise dargestellten Motorspindel;
• 2 eine Detailansicht einer teilweise dargestellten Motorspindel analog der in 1 dargestellten, im Unterschied mit in eine Spindelwelle integrierten Anbauteilen;
• 3 eine Detailansicht einer Lagervorrichtung und einer Kühlvorrichtung zum Kühlen der Lagervorrichtung der in 1 gezeigten Motorspindel;
• 4 unterschiedliche Detailansichten einer teilweise dargestellten Werkzeugschnittstelle der in 1 gezeigten Motorspindel;
• 5 eine Prinzipdarstellung einer Lagervorrichtung einer Motorspindel analog der vorab gezeigten Motorspindeln zur Verdeutlichung einer drehzahlabhängigen Regelung einer axialen Vorspannung der Lagervorrichtung; und
• 6 eine Längsschnittansicht einer teilweise dargestellten Motorspindel gemäß Stand der Technik.

The invention is explained in more detail below using an exemplary embodiment shown in the figures. Show it:

• 1 a longitudinal sectional view of a partially shown motor spindle;
• 2 a detailed view of a partially shown motor spindle analogous to that in 1 shown, in contrast with attachments integrated into a spindle shaft;
• 3 a detailed view of a storage device and a cooling device for cooling the storage device of FIG 1 shown motor spindle;
• 4th different detailed views of a partially shown tool interface of the in 1 shown motor spindle;
• 5 a schematic representation of a bearing device of a motor spindle analogous to the previously shown motor spindles to illustrate a speed-dependent control of an axial preload of the bearing device; and
• 6th a longitudinal sectional view of a partially shown motor spindle according to the prior art.

Description of preferred exemplary embodiments

Before the invention is described in detail, it should be pointed out that it is not restricted to the respective components of the device and the respective method steps, since these components and methods can vary. The terms used here are only intended to describe particular embodiments and are not used in a restrictive manner. If the singular or indefinite article is used in the description or in the claims, this also refers to the majority of these elements, unless the overall context clearly indicates otherwise.

6th shows a partially shown motor spindle 11 in a longitudinal sectional view. First, the 6th the functionality of a motor spindle known as such 11 explained in more detail. The well-known motor spindle 11 has a spindle shaft 19th made of a metallic material. Spindle shaft 19th is by means of bearings 61 to 67 a storage device 23 rotatable in a housing 25th stored. The case 25th also has a metallic material. At a third camp 65 and a fourth camp 67 is a sliding seat 107 provided by means of a spring 105 on a metallic bearing plate 33 is supported. This can cause thermal expansion of the metallic Material of the spindle shaft 19th be balanced. The sliding seat 107 So slides depending on the change in length of the spindle shaft 19th relative to the housing 25th on the end shield 33 along. There are also O-rings 109 for sealing between the sliding seat 107 and the end shield 33 intended.

The main difference to the motor spindles according to the invention described below 11 is that compared to the in 6th metallic materials used have at least one specially adjusted fiber-reinforced plastic material, for example carbon fiber-reinforced plastic fiber material (CFRP material). At least two such materials can be provided particularly advantageously. In addition to others based on the 1 to 5 Advantages explained in more detail, can in particular those in the prior art by means of the sliding seat 107 Realized floating bearings are not required. Instead, at a front end and a rear end of the spindle shaft 19th a fixed bearing can be provided in each case. Due to the advantageous and / or differently adjusted fiber-reinforced plastic materials, there is nevertheless a precise and low-wear bearing of the spindle shaft 19th relative to the housing 25th possible.

1 shows a partially shown motor spindle according to the invention 11 in a longitudinal sectional view. The motor spindle 11 has a spindle shaft 19th on. The spindle shaft 19th is rotatable in a housing by means of a bearing device 25th stored. To this end, the storage device 23 between a front end and a rear end of the spindle shaft 19th two bearing pairs with a first bearing 61 , a second warehouse 63 , a third camp 65 and a fourth camp 67 on. The bearing pairs of the storage device 23 are each by means of one on the spindle shaft 19th seated spacer sleeve 35 and one radially outside of the spacer sleeve 35 arranged outer intermediate ring 81 spaced apart and biased.

The spindle shaft 19th is by means of a drive unit 17th drivable. At the drive unit 17th it is an electric machine with a stator 113 , Magnets 91 and an iron sheet 93 . The magnets 91 and the iron sheeting 93 are radially outside on a rotor-arm 97 recorded. The rotor arm 97 again sits directly on the spindle shaft 19th . In addition, the magnets are radially outside 91 a cover in the form of a sleeve 95 intended. The storage device 23 points radially above the bearing 61 to 67 two end shields 33 on. Radially above the end shields 33 is a cooling sleeve 79 arranged together with the housing 25th a fluid path for guiding a second heat conducting medium 43 provides. In the case of the second heat transfer medium 43 it can be a liquid such as water. The second heat transfer medium 43 circulates through the fluid path and is used to cool the motor spindle 11 , especially about the end shields 33 to cool the bearings 61 to 67 the storage device 23 . In addition, via the fluid path, which is also radially above the drive unit 17th runs, a waste heat generated by this can be dissipated.

The water fluid path, the cooling sleeve 79 and the case 25th are part of a cooling device 29 the motor spindle 11 .

For preloading the storage device 23 and to close the housing 25th indicates the motor spindle 11 at a front end a slinger 101 and a front cover 103 on. The slinger 101 is radially outward with the spindle shaft 19th mounted, for example by means of a press fit, a screw connection to the spindle shaft and / or another connection technology such as gluing, bonding and / or the like. The front lid 103 is with a front of the end shields 33 assembled. Analogously, there is a rear clamping cap at a rear end of the motor spindle 85 on the spindle shaft 19th assembled. There is also one at a rear of the end shields 33 provided rear lid 83 assembled. On the back cover 83 and the rear clamping cap 85 is the fourth camp 67 supported. On the slinger 101 and the front cover 103 is the first camp 61 the storage device 23 supported.

The motor spindle 11 also has one only in the 4a and b shown tool holder 13 for connecting one only by means of the reference number 15th indicated tool with the spindle shaft 19th the motor spindle 11 on. The tool holder 13 can in a shaft cone 47 in the spindle shaft 19th introduced and coupled there with this. There is also one in the 4a and b tool clamping device partially shown and only indicated 115 inside the spindle shaft 19th arranged. The motor spindle 11 So has with the tool clamping device 115 and the shaft cone 47 a tool interface 21st for detachable, non-rotatable coupling of the tool holder 13 with the spindle shaft 19th on.

As in 1 can also be seen in the spindle shaft 19th radially below the first bearing 61 a temperature sensor 99 integrated. Due to the integrated arrangement of the temperature sensor 99 can be a temperature of the storage device 23 , in particular a bearing inner ring 87 of the first camp 61 can be measured particularly precisely and quickly. Also in the front cover 103 another temperature sensor 99 arranged. This is used to measure a temperature of a first heat-conducting medium, in particular air, which is used for cooling the storage device 23 in the motor spindle 11 is press-fit.

In the 1 shown motor spindle 11 has at least two fiber-reinforced plastic materials, in particular CFRP, which are set differently with regard to a thermal conductivity property and / or a thermal expansion coefficient and / or a rigidity. In particular, the spindle shaft 19th , the housing 25th , the end shields 33 , the spacer sleeve 35 , the shaft cone 47 , a clamping tube 53 the tool interface 21st , an in 1 Another intermediate ring, not shown 57 another storage device 23 , the outer intermediate ring 81 the storage device 23 who have favourited the sleeve 95 the drive unit 17th , the rotor arm 97 the drive unit 17th made of a fiber reinforced plastic material. At least two of them are set differently.

2 shows another partially shown motor spindle 11 in a sectional view analogous to that 1 . Only the differences are discussed below. The main difference in 1 Components mounted on the spindle shaft such as the rotor arm 97 and one radially inward of the spindle shaft 19th arranged holder 77 as an integral part of the spindle shaft 19th executed. The holder 77 serves to support and assemble the tool clamping device, not shown in detail 115 . It can be seen that the first bearing is another difference 61 and the second camp 63 from the front and the third camp 65 and the fourth camp 67 from behind onto the spindle shaft 19th , i.e. on both sides of the integrated rotor arm 97 are mountable. In contrast, all four camps 61 to 67 at the motor spindle 11 according to 1 from the rear onto the spindle shaft 19th upset.

3 shows a detailed view of the storage device 23 to the first camp 61 and the second camp 63 . The storage device 23 is by means of a cooling device 29 coolable. The cooler 29 comprises a first fiber-reinforced plastic material 27 on. This has direction-dependent thermal conductivity properties. More precisely point the spacer sleeve 35 and the bearing shield 33 the first fiber-reinforced plastic material 27 on. The other components described above have a different fiber-reinforced plastic material. The cooler 29 has two cooling circuits in which a first heat conducting medium 41 , here air and the second heat transfer medium, 43, here water, circulate. The flow of the first heat transfer medium 41 and corresponding air fluid paths are indicated by first arrows 117 symbolizes. The water fluid path and thus the flow of the second heat transfer medium 43 is by means of second arrows 119 symbolizes.

As in 3 shown are both in the end shield 33 as well as in the outer intermediate ring 81 the storage device 23 Introduced air fluid paths. The first heat transfer medium 41 flows in through a central fluid path and is thereby radially above the spacer sleeve 35 and correspondingly radially below the outer intermediate ring 81 remaining cavity blown. This wets the first heat-conducting medium 41 a surface 37 the spacer sleeve 35 . As in 3 further to recognize shows the surface 37 the spacer sleeve 35 an indentation in the longitudinal sectional view 39 on. The indentation 39 is accordingly with the first heat transfer medium 41 applied.

The spacer sleeve 35 stands on both sides with the bearing inner rings 87 of the first camp 61 and the second camp 63 in a heat-transferring and force-transferring contact. As with third arrows 121 in 3 symbolizes, there is a heat flow or heat transfer from the bearing inner rings 87 on the spacer sleeve 35 instead of. The heat flow is conducted by means of the motor spindle in a longitudinal direction 11 or the spacer sleeve 35 in these introduced thermal conductive fibers 31 . The thermal fibers 31 can be made on a pitch basis and thus have particularly good thermal conductivity.

With the optional indentation 39 are the heat conducting fibers 31 on a surface 37 cut or lead to this, in particular end just below the surface 37 . This can be done using the third arrows 121 symbolized heat transport from the bearing inner rings 87 via the thermal fibers 31 to the surface 37 the spacer sleeve 35 respectively. On the surface 37 will be in the camps 61 and 63 accruing and there transferred frictional heat from the first heat conducting medium 41 recorded and via two exhaust air ducts from the motor spindle 11 led out.

As also in 3 can be seen, also has the bearing plate 33 the thermal fibers 31 on. These enable a flow of heat, which is also indicated by the third arrows 121 is symbolized, starting from radially below the end shield 33 arranged bearing outer rings 89 of the first camp 61 and the second camp 63 via the preferably metallic cooling sleeve 79 away towards the water fluid path, that is, into the second heat-conducting medium 43 .

Another optional feature is the bearing shield 33 even two differently adjusted fiber-reinforced plastic materials. The thermal fibers 31 are between the water fluid path and the bearing outer ring 89 of the first camp 61 arranged obliquely radially upwards. Between the bearing outer ring 89 of the second camp 63 and the water fluid path, these are radially perpendicular aligned above. As a result, the heat flow can be introduced more uniformly and directed or guided via the second heat-conducting medium 43 respectively. The advantages described above can be achieved in that at least two differently adjusted fiber-reinforced plastic materials, that is to say the first fiber-reinforced plastic material 27 of the end shield 33 and / or the spacer sleeve 35 and at least one further fiber-reinforced plastic material are provided.

4th shows in four views A to D each a highly schematic detail of the tool clamping device 115 as well as a force distribution when clamping and unclamping the tool 15th .

The tool clamping device 115 has an ejection device in addition to components not shown in detail 75 for ejecting the tool holder in the form of the clamping tube 53 on.

In 4A is the tool holder 13 shown in a clamped state. A hollow tapered shank of the tool holder sits here 13 in the shaft cone 47 . The wave cone 47 has a second fiber-reinforced plastic material 45 on. This has a comparatively higher rigidity in a longitudinal direction of the motor spindle than in a circumferential direction of the shaft cone 47 or the spindle shaft 19th . This leads to a surface pressure of the hollow conical shank of the tool holder 13 in the shaft cone 47 , as in 4A shown is comparatively smaller.

4B shows a state of the tool interface 21st , where the clamping tube 53 towards the tool holder 13 is displaced and strikes within the hollow cone shaft. This creates an ejection force 123 in the tool holder 13 initiated a counterforce 125 on the shaft cone 47 induced. It is advantageous because of the second fiber-reinforced plastic material 47 the induced counterforce comparatively low, so that the ejector 75 can be interpreted comparatively weaker. As a result, it can work with lower forces, in particular have comparatively smaller linear drives such as a hydraulic ram. This allows a comparatively smaller motor spindle 11 to be provided. The ejection force 123 and the counterforce 125 are in 4B shown.

In the opposite case, i.e. when clamping the tool holder 13 in the shaft cone 47 the spindle shaft 19th is made using the tool clamping device 115 a resilience 127 from the clamping tube 53 on the hollow taper shank of the tool holder 13 transfer. This is divided into a conical force 129 , the shaft cone 47 and in a stop force 131 that are attached to a plan system 49 at a front end of the spindle shaft 19th occurs. The plan system 49 and the wave cone 47 the spindle shaft 19th form a double fit for the tool holder 13 , taking on the double fit 51 the cone force 129 and the impact force 131 are induced or by this as a counterforce to the clamping force 127 in the tool holder 13 be initiated. The ratio of the impact force is preferably 131 to the cone force 129 70 to 90 to 10 to 30th , preferably about 80 to 20. It can be seen that the conical force is due to the second fiber-reinforced plastic material 45 of the shaft cone 47 is comparatively low, since this has a comparatively low rigidity in the circumferential direction. This also increases the ejection force 123 lower, but due to the comparatively higher rigidity in the longitudinal direction, good longitudinal vibration properties can still be achieved. Simultaneous optimization of both properties would not be possible with conventional metallic materials.

The clamping tube 53 has a third fiber reinforced plastic material 55 with a comparatively high internal damping. As in 4A can be seen schematically from the tool 15th via the tool holder 13 Vibrations on the clamping tube 53 be transmitted. These can be achieved through the third fiber-reinforced plastic material 55 , in particular due to the comparatively high internal damping and the good density to stiffness ratio and / or shifted in a natural frequency to a less disruptive higher frequency range.

5 shows a greatly exaggerated representation of the storage device in the longitudinal direction 23 with the bearings 61 to 67 to illustrate a device for regulating a pretensioning force 69 for preloading the bearings 61 to 67 . The preload force is in 5 symbolized by means of arrows and their effect by means of dash-dotted lines. The bearing outer rings 89 of the second camp 63 and the third camp 65 hit on steps 71 the respective end shields 33 on. As a result, the preload force is applied to this 69 initiated. The bearing outer rings 89 the storage 61 and 63 and the camp 65 and 67 are each through an outer intermediate ring 81 spaced from each other. The outer intermediate rings 81 are each radially inside the end shields 33 arranged between the respective pairs of bearings. The bearing inner rings 87 of the respective bearing pairs are each supported by one on the spindle shaft 19th seated intermediate ring 57 spaced from each other. In addition, the bearing inner rings hit 87 of the second camp 63 and the third camp 65 each on one side of the rotor arm 97 on.

About the axial preload 69 is a distance between the steps 71 less than a length of the rotor arm 97 . The difference can be, for example, 30 µm, optionally between 25 and 35 µm. Also are the intermediate rings 57 each shorter than the outer intermediate rings 81 . The difference can be approximately 10 µm, in particular between 8 and 12 µm. In one operation of the motor spindle 11 , i.e. when the spindle shaft is rotating rapidly 19th tend rolling elements 111 the storage 61 to 67 radially outwards, resulting in an increase in the preload force 69 . This effect, known as kinematic displacement, causes a comparatively higher bearing friction at high speeds and thus a comparatively high heat flow, which in 3 using the third arrows 121 is symbolized. This causes the intermediate ring to heat up 57 comparatively strong.

The respective intermediate ring advantageously has 57 a fourth fiber-reinforced plastic material 59 on. This has a coefficient of thermal expansion that differs from the other components and is, for example, less than zero. This means that there is a length of the intermediate rings 57 changed with a temperature increase relative to the other components, in particular shortened. The other components, in particular the respective outer intermediate rings 81 , the spindle shaft 19th and / or the rotor arm 97 have a different material, in particular fiber-reinforced plastic material, in particular with a thermal expansion coefficient of zero or approximately zero. As a result, the difference in length between the respective outer intermediate ring 81 and the intermediate ring 57 be enlarged. This leads to a reduction in the preload force 69 . The rotor arm 97 can also be used as a spacer sleeve between the bearings 61 and 63 and the camp 65 and 67 understand. This can optionally additionally or alone the fourth fiber-reinforced plastic material 59 have, in particular CFRP. This means that it can also be used by setting the coefficient of thermal expansion differently to adjust the preload or the axial preload force 69 adjust, control and / or regulate.

In the 5 Arrangement of the storage device shown 23 thus provides a controller for speed-dependent adjustment of the preload force 69 the storage 61 to 67 ready.

First, the operation of the motor spindle becomes concrete 11 a speed-dependent heat flow in the bearings 61 to 67 generated. The heat flow is not only dependent on the speed, but also from the kinematic displacement of the rolling elements 111 caused an increase in the preload force 69 dependent. The preload force can therefore be used as the control variable of the control loop 69 be considered. This is indicated indirectly by means of the third arrows 121 symbolized heat flow measured by the intermediate ring as a measuring element. In addition to the measuring element, this also represents the final control element of the control loop. The intermediate ring 57 shortens due to the properties of the fourth fiber-reinforced plastic material 59 by means of the temperature increase generated by the introduced heat flow relative to the other parts in the power flow. Shortening the intermediate ring 57 causes a reduction in the axial preload force 69 the storage device 23 . In the 5 Storage device shown 23 is free of loose bearings and directly on the spindle shaft 19th put on. In particular the bearing inner rings 87 are therefore directly on the spindle shaft 19th held, in particular by means of a press fit. This is made possible by the advantageous different fiber-reinforced plastic materials, in particular by the in 5 more detailed regulation of the pre-tensioning force 69 enables.

As in 3 shown it is possible to use the intermediate rings 57 to cool, which improves the timing of the control loop. In particular, this makes the measuring section of the control loop faster.

According to a further aspect of the invention, the spindle shaft 19th radially below the bearings 61 to 67 , more precisely radially below the bearing inner rings 87 a fifth fiber reinforced plastic material 73 on. This points in the circumferential direction of the spindle shaft 19th a reduced rigidity than in the longitudinal direction of the spindle shaft 19th . This leads to a greater expansion of the spindle shaft at high speeds 19th he follows. This is preferably increased so much that it causes the bearing inner rings to lift off 87 the storage 61 to 67 from the spindle shaft 19th can be prevented. In addition, this effect can also be used to increase the pre-tensioning force 69 In addition to influencing the control loop described above, it can be influenced directly as a function of centrifugal force and thus as a function of the speed. The setting of the fifth fiber-reinforced plastic material 73 so clamps the bearings from radially below 61 to 67 optionally also dependent on the speed. This enables a pretensioning force that is virtually constant over the entire speed range of the motor spindle 69 be effected.

The invention is not limited to the individual exemplary embodiments. Rather, the individual exemplary embodiments can be combined to form new designs. In particular, the advantages of the cooling and regulation described above can be combined with one another in one component, for example.

List of reference symbols

11

Motor spindle

13

Tool holder

15th

Tool

17th

Drive unit

19th

Spindle shaft

21st

Tool interface

23

Storage device

25th

casing

27

first fiber-reinforced plastic material

29

Cooling device

31

Thermal fiber

33

Bearing shield

35

Spacer sleeve

37

surface

39

indentation

41

first heat transfer medium

43

second heat transfer medium

45

second fiber-reinforced plastic material

47

Shaft cone

49

Plan system

51

Double fit

53

Clamping tube

55

third fiber reinforced plastic material

57

Intermediate ring

59

fourth fiber-reinforced plastic material

61

first camp

63

second camp

65

third camp

67

fourth camp

69

Preload

71

step

73

fifth fiber-reinforced plastic material

75

Ejector

77

holder

79

Cooling sleeve

81

outer intermediate ring

83

rear lid

85

rear clamping cap

87

Bearing inner ring

89

Bearing outer ring

91

Magnets

93

Iron sheeting

95

Sleeve

97

Rotor arm

99

Temperature sensor

101

Sling disc

103

front lid

105

feather

107

Sliding seat

109

O-ring

111

Rolling elements

113

stator

115

Tool clamping device

117

first arrow

119

second arrow

121

third arrow

123

Ejection force

125

Counterforce

127

Resilience

129

Conical force

131

Impact force

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• EP 3069848 A1 [0002]
• DE 19726341 A1 [0002]
• DE 4009461 A1 [0002]

Claims (16)

Motor spindle (11) for driving a tool (15) clamped directly or held in a tool holder (13), with: - a spindle shaft (19) driven by means of a drive unit (17), - a tool interface (21) for the detachable, rotationally fixed coupling of the tool holder (13) with the spindle shaft (19), - a bearing device (23) for rotatably supporting the spindle shaft (19), - a housing (25) in which the spindle shaft (19), the bearing device (23) and the drive unit (17 ), characterized in that the motor spindle (11) has at least two fiber-reinforced plastic materials which are set differently in terms of rigidity, heat conductivity and / or a coefficient of thermal expansion. Motor spindle after Claim 1 , characterized in that a first (27) of the fiber-reinforced plastic materials is arranged between the storage device (23) and a cooling device (29) which has a direction-dependent thermal conductivity which occurs in a direction between the storage device (23) and the cooling device ( 29) is increased. Motor spindle after Claim 2 , characterized in that the first fiber-reinforced plastic material (27) has aligned heat-conducting fibers (31). Motor spindle after Claim 3 , characterized in that the heat conducting fibers (31) run essentially between the bearing device (23) and the cooling device (29). Motor spindle according to one of the Claims 3 or 4th , characterized in that a bearing plate (33) and / or a spacer sleeve (35) of the bearing device (23) has the first fiber-reinforced plastic material (27). Motor spindle according to one of the Claims 3 to 5 , characterized in that the heat conducting fibers (31) are cut on a surface (37) or at least run towards the surface (37). Motor spindle according to one of the Claims 5 or 6th , characterized in that the spacer sleeve (35) has an indentation (39) in which the heat-conducting fibers end, the indentation (39) being able to be acted upon by a heat-conducting medium (41) to transport heat away. Motor spindle according to one of the preceding claims, characterized in that a second (45) and / or fifth (73) of the fiber-reinforced plastic materials is / are arranged at the tool interface (21) and / or radially below the bearing device (23), which are in a Longitudinal direction of the spindle shaft (19) of the motor spindle (11) have a comparatively higher rigidity than in a circumferential direction of the spindle shaft (19). Motor spindle after Claim 8 , characterized in that a shaft cone (47) of the spindle shaft (19) which cooperates with the tool holder (13) has the second fiber-reinforced plastic material (45). Motor spindle after Claim 9 , characterized in that the spindle shaft (19) has a flat contact (49) cooperating with the tool holder (13), the flat contact (49) and the shaft cone (47) acting as a double fit (51) for the tool holder (13), wherein a clamping force (127) for clamping the tool holder (13) is distributed in a ratio of 90 to 70 to 10 to 30, preferably approximately 80 to 20, on the plane system (49) to the shaft cone (47). Motor spindle according to one of the preceding claims, characterized in that a clamping tube (53) of the tool interface (21) has a third (55) of the fiber-reinforced plastic materials, the third fiber-reinforced plastic material (55) having a comparatively high internal damping. Motor spindle according to one of the preceding claims, characterized in that a fourth (59) of the fiber-reinforced plastic materials has a coefficient of thermal expansion that differs from a further component of the motor spindle (11) and / or an intermediate ring (57) of the bearing device (23) the fourth fiber-reinforced plastic material ( 59). Motor spindle after Claim 12 , characterized in that the fourth fiber-reinforced plastic material (59) and / or the intermediate ring (57) is arranged between two bearings (61, 63; 65, 67) of the bearing device (23), an axial pretensioning force (69 ) can be transferred to the bearings (61, 63; 65, 67) and a heat flow can be introduced from the bearings (61, 63; 65, 67) into the fourth fiber-reinforced plastic material (59) and / or into the intermediate ring (57), wherein a temperature increase of the fourth fiber-reinforced plastic material (59) and / or of the intermediate ring (57) causes a reduction in the axial pretensioning force (69). Motor spindle after Claim 12 or 13 , characterized in that the motor spindle has a control loop for regulating the axial pretensioning force (69), the fourth being fiber-reinforced The axial pretensioning force (69) is applied to plastic material (59) and, in combination with the further component, forms a measuring element and / or actuator of the control circuit. Method for regulating a bearing device (23), in particular a bearing device of a motor spindle (11) according to one of the preceding claims, characterized by : - generating a heat flow (121) of a bearing device (23) of the motor spindle (11) occurring during operation, - introducing it of the heat flow (121) in a first component of the bearing device (23) which is subjected to an axial preload force, - changing a length of the first component by means of a temperature increase generated by the heat flow (121) generated relative to another component of the bearing device (23), - Controlling the axial pretensioning force (69) by changing the length of the first component relative to the further component. Procedure according to Claim 15 , characterized by : - introducing the heat flow into an intermediate ring (57) of the bearing device (23) as the first component, - shortening the intermediate ring (57) relative to a spindle shaft (19) which supports it as the second component by means of the heat flow introduced through it (121) generated temperature increase, - reducing an axial preloading force (69) of the bearing device (23) by means of shortening the intermediate ring (57) relative to the spindle shaft (19).

Images