DE102018119477B4 - Spindle arrangement for a machine tool - Google Patents

Abstract

Spindle arrangement (10) for a machine tool, with a shaft (13) which is rotatably mounted about a longitudinal axis (L) in a spindle housing (12) and has a front shaft part (13a) and a rear shaft part (13b), which by means of a Coupling device (14) are detachably non-rotatably connected to one another, with a motor (20) which is drivingly coupled to the rear shaft part (13b), the front shaft part (13a) being connected at its end opposite the coupling device (14) for connection to a tool ( 11) with a first roller bearing arrangement (28) which rotatably mounts the front shaft part (13a) on the spindle housing (12) at the end region opposite the coupling device (14), the first roller bearing arrangement (28) being radial to the longitudinal axis (L) has a first radial bearing rigidity (C1), with a second roller bearing arrangement (33) which has a front roller bearing (34) which rotates the front shaft part (13a) adjacent to the coupling device (14) r is mounted on the spindle housing (12), and has a rear roller bearing (35) which rotatably supports the rear shaft part (13b) on the spindle housing (12) adjacent to the coupling device (14), the second roller bearing arrangement (33) being designed in this way or wherein the second roller bearing arrangement (33) and the coupling device (14) are designed such that the front shaft part (13a) is supported radially to the longitudinal axis (L) immediately after the coupling device (14) with a second radial bearing rigidity (C2), which is at most 80% of the first radial bearing rigidity (C1), and wherein the second roller bearing arrangement (33) and / or the coupling device (14) has at least one damping element (40, 47) which is set up to prevent radial movement of the shaft ( 13) dampen.

Description

The invention relates to a spindle arrangement for a machine tool with a shaft which is rotatably mounted about a longitudinal axis in a spindle housing.

To mount shafts in a housing, it is known to use roller bearing arrangements or roller bearing sets. EP 1 961 101 B1 describes a shaft rotatably driven by an electric motor, which is mounted on a motor housing by means of two bearing arrangements. One, front bearing arrangement, is designed as a fixed bearing. The rear bearing arrangement arranged on the other side of the motor is designed as a floating bearing in order to enable the shaft to move axially. For this purpose, the rear roller bearing arrangement is slidably arranged in a corresponding recess on the motor housing and is radially preloaded via spring elements.

DE 10 2009 031 027 A1 describes a split tool spindle. The tool spindle has a spindle head that is set up for coupling with a tool. A spindle shaft is supported in the spindle head via a front roller bearing and a rear roller bearing. The spindle head can be coupled to a spindle motor. The motor shaft is supported on the opposite side of the coupling via a rear roller bearing and there is another front roller bearing on the coupling.

Out DE 10 2017 105 934 A1 a machine spindle arrangement for a machine tool is known in which the shaft of the spindle is supported by a plurality of bearings. The machine spindle having the shaft can be coupled to a structural unit having a motor.

For machine tool spindles, forces are introduced into the spindle or shaft while a workpiece is being machined. The forces depend on the type of machining and act axially and / or radially on the rotating tool and thus on the rotatingly driven shaft. Depending on the force applied, the feed movement of the tool relative to the workpiece, the depth of cut and other parameters, mechanical vibrations can occur in the shaft, which lead to the tool “rattling” during workpiece machining and negatively affect the surface quality of workpiece machining.

It can therefore be regarded as an object of the present invention to provide a maintenance or repair-friendly spindle arrangement by means of which vibrations of the shaft are reduced.

This object is achieved by a spindle arrangement with the features of claim 1.

The spindle arrangement has a shaft which is rotatably mounted about a longitudinal axis in a spindle housing. The shaft has a front shaft part and a rear shaft part. The two shaft parts are detachably and non-rotatably connected to one another by means of a coupling device. A motor is drive-coupled to the rear shaft part. When the rear shaft part is driven by the motor, the rotary movement is transmitted to the front shaft part via the coupling device. The front shaft part is set up at a front end opposite the coupling device for connection to a tool. For this purpose, a tool holder can be connected to the front shaft part in a rotationally fixed manner on the front shaft part.

The spindle arrangement has a first roller bearing arrangement with one or more roller bearings, which rotatably supports the front shaft part adjacent to the front end on the spindle housing. The first roller bearing arrangement supports the front shaft part with a first radial bearing stiffness radially to the longitudinal axis.

The shaft is rotatably mounted on the spindle housing adjacent to the coupling device via a second roller bearing arrangement. For this purpose, the second roller bearing arrangement has a front roller bearing that rotatably supports the front shaft part on the spindle housing, and a rear roller bearing that rotatably supports the rear shaft part on the spindle housing. The second roller bearing arrangement and / or the coupling device are designed in such a way that the front shaft part is mounted or supported on the spindle housing radially to the longitudinal axis immediately after the coupling device with a second radial bearing rigidity. The second radial bearing stiffness is smaller than the first radial bearing stiffness and is a maximum of 80% of the first radial bearing stiffness.

The second radial bearing rigidity is preferably a maximum of 55-65% or a maximum of 50% or a maximum of 30% or a maximum of 20% of the first radial bearing rigidity. It is also preferred if the second radial bearing rigidity is at least 1% to at least 5% of the first radial bearing rigidity.

The specified ratios of the radial bearing stiffness refer to both the stationary and the rotating shaft.

Due to these different radial bearing stiffnesses of the shaft directly adjacent to the tool on the one hand and directly adjacent to the coupling device, on the other hand, bending vibrations that are introduced into the shaft during the machining of a workpiece can be damped. Because of the second radial bearing stiffness in the area of the coupling device, which is lower than the first radial bearing stiffness, the shaft can move radially to the longitudinal axis in the area of the coupling device, this movement being damped by the second roller bearing arrangement and / or the coupling device. It has been shown that vibration excitation subsides faster and the load on the coupling device in the radial direction can be reduced. With such an embodiment, significantly higher cutting depths can be achieved with the same tool and the same geometry of the spindle arrangement, which can be four to ten times greater than with known spindle arrangements. This significantly increases the productivity of a machine tool. The split shaft makes it easy to remove and install, which simplifies maintenance or repair.

According to the invention, the second roller bearing arrangement and / or the coupling device has at least one damping element. The at least one damping element is designed to dampen a radial movement of the shaft. The damping element can consist of elastically deformable material or have elastically deformable material.

In one embodiment, at least one damping element of the existing at least one damping element is arranged between the front roller bearing and the spindle housing and / or between the rear roller bearing and the spindle housing. Such a damping element can be, for example, an elastomer ring or an O-ring. Alternatively or additionally, at least one damping element can also be arranged between the front roller bearing and the front shaft part and / or between the rear roller bearing and the rear shaft part.

Alternatively or additionally, at least one damping element of the at least one damping element can be arranged between a front coupling part and a rear coupling part of the coupling device and dampen a radial movement of the two coupling parts relative to one another. The front coupling part is rotatably connected to the front shaft part and the rear coupling part is rotatably connected to the rear shaft part. The connection between the two coupling parts of the coupling device is preferably carried out in such a way that no or only negligible torsion occurs between the two shaft parts under the load occurring during operation of the spindle arrangement. In order to enable a radial displacement between the two coupling parts, elastic material can be arranged between the two coupling parts. A coupling device that meets these requirements is available on the market, for example the Rotex® coupling from the manufacturer KTR Systems GmbH.

It is also advantageous if the front roller bearing and the rear roller bearing each have a radial bearing stiffness that is less than the second radial bearing stiffness. The sum of the two radial bearing stiffnesses of the front and rear rolling bearings can correspond to the second radial bearing stiffness in this arrangement.

In a preferred embodiment, a third roller bearing arrangement is present. The third roller bearing arrangement rotatably supports the rear shaft part on the spindle housing. The motor preferably acts on the rear shaft part between the second roller bearing arrangement and the third roller bearing arrangement.

It is advantageous if the motor is arranged coaxially with the longitudinal axis. As a result, the rotor can, for example, be connected to the rear shaft part in a torque-proof manner, directly or indirectly. It is preferred if the motor, viewed in the direction parallel to the longitudinal axis, is arranged between the second roller bearing arrangement and the third roller bearing arrangement.

The roller bearing arrangements preferably each have at least one roller bearing which is designed as an angular bearing. The angular contact bearings are axially tightened using suitable parallel to the longitudinal axis, prestressed.

In a preferred embodiment, the rear roller bearing of the second roller bearing arrangement and a roller bearing of the third roller bearing arrangement are arranged in such a way that intersections of the lines of action of the roller bearings with the longitudinal axis result which are axial, i.e. in the direction of the longitudinal axis, between the rear roller bearing and the roller bearing of the third roller bearing arrangement. Such an arrangement of rolling bearings is also referred to as an X arrangement. With such an arrangement, the radial bearing rigidity of the bearing of the rear shaft part can be reduced compared to other bearing arrangements. Such an X arrangement as a bearing arrangement can be provided as an alternative or in addition to further measures in order to achieve the second radial bearing rigidity.

Alternatively or additionally, in one embodiment, the number of rolling elements of the front rolling bearing and / or the rear one Rolling bearing of the second rolling bearing arrangement can be selected such that the second radial bearing rigidity is achieved. This measure is suitable as an alternative or in addition to other measures in order to achieve the desired second radial bearing rigidity of the front shaft part immediately adjacent to the coupling device or to the front coupling part. The lower the number of rolling elements in a rolling bearing, the lower the radial bearing rigidity.

It is preferred if the first roller bearing arrangement has two roller bearings which are arranged such that there are intersections of the lines of action with the longitudinal axis which are axial, i.e. in the direction of the longitudinal axis, on the side facing away from the other roller bearing, roller bearings of the first roller bearing arrangement are arranged. Such a bearing arrangement is also referred to as an “O” arrangement and enables the front shaft part adjacent to the tool to be very well supported against initiated torques which attempt to incline or tilt the front shaft part with respect to the longitudinal axis.

As an alternative to this, the roller bearings of the first roller bearing arrangement can also be arranged in a tandem arrangement, such that the lines of action of the roller bearings are parallel or essentially parallel, so that intersections of the lines of action with the longitudinal axis result, each in the same axial direction as the respective roller bearing are offset along the longitudinal axis. In addition, the first roller bearing arrangement can also have only a single roller bearing.

It is also advantageous if the outer diameter of the front roller bearing of the second roller bearing arrangement is smaller than the outer diameter of the first roller bearing arrangement. This makes it possible in a simple manner to remove or reinstall the front shaft part axially along the longitudinal axis from the spindle housing. The split shaft enables the front shaft part to be quickly replaced if this is necessary due to damage.

• 1 eine schematische, blockschaltbildähnliche Darstellung eines Ausführungsbeispiels einer Spindelanordnung,
• 2 eine schematische Prinzipdarstellung einer Biegeschwingung einer Welle der Spindelanordnung aus 1,
• 3-6 jeweils eine schematische Darstellung eines Ausführungsbeispiels eines Wälzlagers einer zweiten Wälzlageranordnung für die Spindelanordnung aus 1,
• 7 eine schematische Darstellung zur Reduzierung einer radialen Lagersteifigkeit vom Wert Ca auf den Wert Cb für ein Wälzlager der zweiten Wälzlageranordnung für die Spindelanordnung,
• 8 eine schematische, blockschaltbildähnliche Darstellung eines weiteren Ausführungsbeispiels einer Spindelanordnung und
• 9 und 10 jeweils eine schematische, blockschaltbildähnliche Darstellung eines weiteren Ausführungsbeispiels einer Spindelanordnung.

Advantageous embodiments of the invention result from the dependent patent claims, the description and the drawings. Preferred exemplary embodiments of the invention are explained in detail below with reference to the attached drawings. Show it:

• 1 1 shows a schematic illustration, similar to a block diagram, of an exemplary embodiment of a spindle arrangement,
• 2nd is a schematic diagram of a bending vibration of a shaft of the spindle assembly 1 ,
• 3-6 each a schematic representation of an embodiment of a rolling bearing of a second rolling bearing arrangement for the spindle arrangement 1 ,
• 7 a schematic representation for reducing a radial stiffness of the value Approx on the value Cb for a roller bearing of the second roller bearing arrangement for the spindle arrangement,
• 8th is a schematic, block diagram-like representation of a further embodiment of a spindle arrangement and
• 9 and 10 each a schematic, block diagram-like representation of a further embodiment of a spindle arrangement.

In 1 is an embodiment of a spindle assembly 10 illustrated for a machine tool. The spindle arrangement 10 is set up a tool 11 rotating around a longitudinal axis L drive to machine a workpiece. The spindle arrangement 10 can be positioned or aligned, for example, by means of at least one translatory and / or at least one rotary machine axis of the machine tool.

The spindle arrangement 10 has a spindle housing 12th in which a wave 13 rotatable around the longitudinal axis L is stored. The wave 13 is designed as a split shaft and has a front shaft part 13a and a rear shaft part 13b . The two shaft parts 13a , 13b are by means of a coupling device 14 non-rotatably connected. This non-rotatable connection is separable around the front shaft part 13a , from the rear shaft part 13b to separate and especially around the front shaft part 13a along the longitudinal axis L from the spindle housing 12th to be able to remove. The coupling device 14 has a front coupling part 14a that firmly with the front shaft part 13a connected is. The coupling device 14 also has a rear clutch part 14b that firmly with the rear shaft part 13b connected is. To separate the two shaft parts 13a , 13b can the coupling device 14 between the coupling parts 14a , 14b be separated.

The rear shaft part 13b is by means of an engine 20 and in particular an electric motor or servo motor. The motor 20 has a rotor 21st and a stator 22 . The rotor 21st is with the rear shaft part 13b connected to the drive. In the exemplary embodiment described here, the rotor 21st and the stator 22 coaxial to the longitudinal axis L arranged. The motor 20 is designed as an internal rotor motor and the rotor 21st can be rotatably connected directly or via suitable mechanical connecting means to the rear shaft part 13b be connected. The rotor 21st is especially as a permanently excited rotor 21st executed.

The front shaft part 13a has on its the coupling device 14 opposite tool-side end means for receiving the tool 11 . In the illustrated embodiments, the tool-side end of the shaft 13 (front end of the front shaft part 13a ) a tool holder 23 be attached in a rotationally fixed manner to accommodate the tool 11 is set up. Depending on the tool used, different tool holders can be used 23 interchangeable on the shaft 13 to be ordered. The tool holder 23 is located outside the spindle housing, for example 12th , as an alternative to the schematic representation, can be at least partially in the spindle housing 12th protrude.

To support the shaft 13 are several roller bearing arrangements between the shaft 13 and the spindle housing 12th available. A recording room 24th in the spindle housing 12th is cylindrical for this at least in sections. The recording room 24th takes the wave 13 , the coupling device 14 , the engine 20 and several roller bearing arrangements, which are described in more detail below.

Immediately adjacent to the tool holder 23 or in one of the coupling devices 14 opposite end area is the front shaft part 13a by means of a first roller bearing arrangement 28 rotatable on the spindle housing 12th stored. The first rolling bearing arrangement 28 has at least one rolling bearing, which is designed as an angular bearing in the embodiment. The first rolling bearing arrangement 28 has a first rolling bearing 29 and a second rolling bearing 30th on. The first rolling bearing 29 and the second rolling bearing 30th are in the direction of the longitudinal axis L directly adjacent to each other or at a distance from each other. The first rolling bearing 29 is closer to the tool holder 23 than the second rolling bearing 30th . The distance of the first rolling bearing arrangement 28 and especially the second rolling bearing 30th from the tool holder 23 is smaller, for example at least a factor of 1.5 or 2 smaller than the distance between the first roller bearing arrangement 28 and especially the second rolling bearing 30th from the coupling device 14 . The first rolling bearing 29 and the second rolling bearing 30th have through the training as angular contact lines of action that the longitudinal axis L cut at a pressure angle that is less than 90 degrees. The lines of action W the angular bearings are particularly in 1 schematically illustrated. The first lines of action W1 of the first rolling bearing 29 intersect on the second rolling bearing 30th facing away from the axial side with the longitudinal axis L . The second lines of action W2 of the second rolling bearing 30th intersect on the the first rolling bearing 29 facing away from the axial side with the longitudinal axis L . The roller bearings 29 , 30th the first rolling bearing arrangement 28 form a so-called O arrangement. Immediately at the connection to the tool holder 23 becomes the front shaft part 13a through the first rolling bearing arrangement 28 therefore not only radial to the longitudinal axis L or along the longitudinal axis L but also braced against tilting moments trying to hit the front shaft part 13a against the longitudinal axis L the spindle arrangement 10 to tilt or tilt.

The first rolling bearing arrangement 28 supports the front shaft part 13a radial to the longitudinal axis L with a first radial bearing rigidity C1 from.

The spindle arrangement 10 also has a second rolling bearing arrangement 33 on. The second rolling bearing arrangement 33 has at least two roller bearings, for example a front roller bearing 34 and a rear rolling bearing 35 form. In one embodiment, the front and rear bearings are 34 , 35 are designed as angular bearings and in another embodiment, the front and / or the rear roller bearing 34 , 35 be designed as a pure radial bearing (e.g. cylindrical roller bearing). The front roller bearing 34 supports the front shaft part 13a adjacent to the coupling device 14 rotatable on the spindle housing 12th . The rear roller bearing 35 supports the rear shaft part 13b adjacent to the coupling device 14 rotatable on the spindle housing 12th .

In the illustrated embodiment, there is also a third rolling bearing arrangement 36 present that the rear shaft part 13b rotatable on the spindle housing 12th stores. The third rolling bearing arrangement 36 has a single rolling bearing in the exemplary embodiment, the third rolling bearing 37 referred to as.

In a modification of the exemplary embodiment, the number of roller bearings or angular bearings of the roller bearing arrangements can 28 , 33 , 36 and / or the alignment of the lines of action vary. In particular, any rolling bearing arrangement 28 , 33 , 36 also have more separate rolling bearings than described above and illustrated in the drawings. For example, all rolling bearings are designed as angular bearings, with each rolling bearing arrangement 28 , 33 , 36 can also have at least one pure radial bearing, for example a cylindrical roller bearing.

The motor 20 is in the embodiment between the second rolling bearing arrangement 33 and the third rolling bearing arrangement 36 coaxial to the longitudinal axis L arranged. It is located in particular between the rear roller bearing 35 of the second rolling bearing arrangement 33 and the third roller bearing 37 the third rolling bearing arrangement 36 .

In one embodiment according to 1 are the front roller bearings 34 and the rear roller bearing 35 the second rolling bearing arrangement 33 designed such that the shaft 13 in the area of the coupling device 14 with a second radial bearing rigidity C2 is stored, which is a maximum of 80% and preferably a maximum of 55-65% or a maximum of 20-30% of the first radial bearing rigidity C1 is. This is with the in 1 illustrated preferred embodiment achieved in that the front roller bearing 34 and the rear roller bearing 35 each have at least one damping element 40 exhibit. The at least one damping element is designed to move the shaft 13 radial to the longitudinal axis L on the front roller bearing 34 or on the rear roller bearing 35 allow and dampen this movement. The at least one damping element 40 can for example consist of elastic material or have elastic material.

In the 3-6 are exemplary embodiments for the arrangement of the at least one damping element 40 shown schematically as an example. For example, the at least one damping element 40 between the relevant front roller bearing 34 and / or rear roller bearings 35 and the spindle housing 12th be arranged ( 3rd , 4th and 6 ) or additionally or alternatively, at least one damping element 40 between the front roller bearing 34 or the rear roller bearing 35 and the wave 13 be arranged ( 5 ).

In a preferred embodiment, this is at least one damping element 40 formed by an elastomer ring or an O-ring and thus provides a damping ring 41 The damping ring 41 can in a groove 42 be arranged either in the front roller bearing 34 or rear rolling bearing 35 ( 3rd and 5 ) and / or in the spindle housing 12th ( 4th ) or in the wave 13 (not shown) is introduced. In the embodiments according to the 3-5 have the grooves 42 and the damping rings 41 one dimension parallel to the longitudinal axis L considered, which is smaller than half the width of the front bearing in question 34 or rear rolling bearing 35 . Thus two grooves can 42 with damping rings arranged in it 41 be arranged side by side in an axial section which is at most as large as the width of the rolling bearing in question 34 or. 35 .

In 6 An embodiment is shown in which an annular damping element 40 has an axial dimension that is greater than the corresponding axial dimension of the rolling bearing 34 or. 35 . The ring-shaped damping element 40 has a cross section in this embodiment, the dimension parallel to the longitudinal axis is significantly larger than radial, in particular at least by a factor 4-5 .

The front roller bearing 34 and the rear roller bearing 35 each have an outer ring 44 , an inner ring 45 as well as between the outer ring 44 and the inner ring 45 arranged rolling elements 46 which can be formed, for example, by balls. In the embodiments according to the 3rd , 4th and 6 is between the outer ring 44 and the spindle housing 12th A gap S formed in which the at least one damping element 40 protrudes and the front roller bearing 34 or rear roller bearings 35 elastic, play-free between the shaft 13 and the spindle housing 12th supported radially. Additionally or alternatively, a gap can also be used S between the inner ring 45 and the wave 13 to be available ( 5 ) in which the at least one damping element 40 protrudes and the front roller bearing 34 or rear roller bearings 35 radial clearance between the shaft 13 and the spindle housing 12th supports. To this gap S corresponding amount can be the wave 13 in the area of the coupling device 14 on the second rolling bearing arrangement 33 relative to the spindle housing 12th move, this movement by the at least one damping element 40 is dampened. As a result, bending vibrations with a maximum or approximately maximum, predominantly radial amplitude A in the area of the second roller bearing arrangement 33 approved and damped. Such a bending vibration is shown schematically in 2nd illustrated.

It has been shown that such an arrangement with the same geometry of the spindle arrangement 10 and the same tool 11 significantly higher cutting depths can be achieved in one workpiece. Is the radial bearing rigidity C2 the second rolling bearing arrangement 33 roughly as large as the first radial bearing rigidity C1 the first rolling bearing arrangement 28 , a rattling feed movement occurs between the tool at greater depths of cut 11 and on the workpiece and the surface quality at the material removal point suffers. In addition, the loads on the spindle arrangement 10 very high, which consequently causes wear and the service life of the spindle arrangement 10 or the tool 11 can reduce. These disadvantages are eliminated in that the second radial bearing rigidity C2 is chosen to be significantly smaller than the first radial bearing rigidity C1 .

In 7 is schematically illustrated a way to value the radial bearing rigidity of a rolling bearing Approx on the value Cb to reduce. Links in 7 is a roller bearing with the outer ring 44 , the inner ring 45 and the rolling bearing bodies 46 illustrated in a side view. in the left picture the rolling bearing has a radial bearing stiffness with an amount according to a radial initial stiffness Approx . By reducing the number of rolling elements 46 can this radial initial stiffness Approx are reduced to a reduced radial bearing rigidity Cb (on the right in the representation in 7 ). Such a measure can be used as an alternative or in addition to arranging at least one damping element 40 the radial bearing rigidity of the front roller bearing 34 or the rear roller bearing 35 the second rolling bearing arrangement 33 be reduced.

Therefore, the front and / or the rear roller bearing 34 , 35 fewer rolling elements 46 have than the first and the second rolling bearing 29 , 30th . For the front and / or rear rolling bearing 34 , 35 can in particular also the ratio of the number of rolling elements 46 divided by the radius of the rolling element path can be smaller than in the first and second rolling bearings 29 , 30th . The rolling element path is the circular path around the center of the rolling bearing on which the center points of the rolling elements 46 are located.

8th shows a further embodiment of the spindle arrangement 10 . The main structure of the spindle arrangement 10 corresponds to the embodiment according to 1 , so that reference can be made to the above description. The differences from the exemplary embodiment according to FIG 1 explained.

The second radial bearing rigidity C2 in the area of the coupling device 14 is the front roller bearing 34 the second rolling bearing arrangement 33 and the coupling device 14 formed such that the front shaft part 13a in the area of the front roller bearing 34 and the front coupling part 14a compared to the first radial bearing rigidity C1 lower second radial bearing rigidity C2 having. This is the coupling device 14 formed such that a through elastic material of a damping element 47 the coupling device 14 between the two coupling parts 14a , 14b damped radial movement of the front coupling part 14a against the longitudinal axis L or the rear coupling part 14b is possible. In this version, the rear roller bearing 35 have greater radial bearing rigidity than the front roller bearing 34 or have a radial bearing rigidity that is greater than the second radial bearing rigidity C2 . The second radial bearing rigidity C2 is in this embodiment by the radial coupling between the front coupling part 14a and the rear coupling part 14b as well as the radial bearing rigidity of the front roller bearing 34 certainly. The arrangement is designed such that the front shaft part 13a in the area of the front coupling part 14a with the second radial bearing rigidity C2 radial to the longitudinal axis L on the spindle housing 12th is supported. The front roller bearing 34 the second rolling bearing arrangement 33 can be carried out according to one of the embodiments as described above in connection with the 3-7 have been explained. Combinations of these designs according to the 3-7 are possible.

In the embodiments according to the 1 and 8th are the rear roller bearings 35 the second rolling bearing arrangement 33 and the third rolling bearing 37 the third rolling bearing arrangement 36 designed as an angular bearing and arranged such that the third lines of action W3 of the third rolling bearing 37 an intersection with the longitudinal axis L have, that of the second rolling bearing arrangement 33 opposite axial side. Fourth lines of action W4 of the rear rolling bearing 35 form with the longitudinal axis L an intersection on that of the third rolling bearing arrangement 36 opposite axial side. The rear roller bearing 35 the second rolling bearing arrangement 33 and the third rolling bearing 37 the third rolling bearing arrangement 36 form a so-called O arrangement to tilt the rear shaft part 13b on the spindle housing 12th to be able to support better.

In contrast, they are the rear roller bearings 35 and the third rolling bearing 37 at the in 9 illustrated embodiment arranged such that the intersection of the third lines of action W3 and the fourth lines of action W4 both in the area between the rear roller bearing 35 and the third roller bearing 37 lie, so that an X-arrangement is formed. As a result, the radial bearing rigidity of the support of the rear shaft part 13b deliberately reduced. Analogous to 1 is in accordance with the embodiment 9 one radial to the longitudinal axis L rigid coupling of the front coupling part 14a with the rear coupling part 14b realized. Due to the X arrangement of the rear roller bearing 35 and the third rolling bearing 37 as well as a reduced radial bearing rigidity of the front roller bearing 34 - For example, in a version according to the 3-7 - A radial support of the front shaft part 13a in the area of the front coupling part 14a opposite the spindle housing 12th achieved, which is only slightly stiffer overall than the second radial bearing stiffness C2 .

In one or more embodiments of the spindle arrangement 10 form the front shaft part 13a , the first rolling bearing arrangement 28 , the front roller bearing 34 the second rolling bearing arrangement 33 as well as the front coupling part 14a a unit that is handled together and, for example, from the recording room 24th removed or in the recording room 24th of the spindle housing 12th can be used. For example, an end cover can be used for this purpose 50 of Spindle housing 12th be removed so that the recording room 24th is accessible from the tool end. The assembly from the front shaft part 13a , first rolling bearing arrangement 28 , front roller bearing 34 and front coupling part 14a can along the longitudinal axis L removed, serviced, repaired, at least partially replaced and axially along the longitudinal axis L in the recording room 24th be used. The assembly or disassembly is possible in a short time with little effort. This is achieved or improved in particular in that the outer diameter of the front roller bearing 34 the second rolling bearing arrangement 33 is smaller than the outer diameter of the first roller bearing arrangement 28 . Like it in the 1 , 8th and 9 has illustrated the first rolling bearing arrangement 28 a first outside diameter D1 and the front roller bearing 34 the second rolling bearing arrangement 33 has a second outside diameter D2 that is smaller than the first outside diameter D1 . Through a correspondingly graduated inner diameter of the receiving space 24th can take the paths along which the rolling bearings 29 , 30th , 34 be fitted or pressed in to form a play-free radial bearing, are carried out relatively briefly. This can be the inside diameter of the receiving space 24th following the bearing of the front roller bearing 34 to the first roller bearing arrangement 28 expand accordingly. The first outside diameter D1 and the second outside diameter D2 are only in for reasons of clarity 9 illustrated, the outer diameter D1 , D2 in the embodiments according to the 1 and 8th are identical.

In a further embodiment according to 10 has the spindle housing 12th two spindle housing parts 12a , 12b on and can also be made in two parts. Here form the front part of the shaft 13a , the first rolling bearing arrangement 28 , the front roller bearing 34 the second rolling bearing arrangement 33 , the front coupling part 14a and the first spindle housing part 12a a first unit. The first spindle housing part 12a thus encloses the front shaft part 13a . The second spindle housing part 12b forms together with the engine 20 , the rear coupling part 14b , the rear roller bearing 35 the second rolling bearing arrangement 33 and the third rolling bearing arrangement 36 a second assembly. The second spindle housing part 12b thus encloses the rear shaft part 13b .

The first spindle housing 12a is with the second spindle housing 12b with connecting elements, not shown, such as screws, releasably connected, a coaxial alignment being established via centering means, such as a centering flange.

In the event of a technical defect, the first spindle housing part 12a can be exchanged as a whole, which takes very little time. A first spindle housing part to be replaced 12a is made up in such a way that deviations in length that affect tools are only a few micrometers, for example 1 to 2 micrometers. Machine tools with such spindles, which are also referred to as zero spindles, can be used without further measurement or adjustment work and without loss of quality immediately after replacement, so that high productivity can be achieved. The internal structure of the first spindle housing part 12a is the same as in the above-described embodiments, so that the advantages described above also come into play here when the defective components are repaired.

The invention relates to a spindle arrangement 10 with one in a spindle housing 12th rotatable shaft 13 . The wave 13 is at one end of the spindle housing 12th accessible and there for holding a tool 11 furnished or configurable. The tools 11 can be done directly or indirectly by arranging a tool holder 23 on the shaft 13 be clamped. The wave 13 is divided and has a tool-side front shaft part 13a and a motor-side rear shaft part 13b . The two shaft parts are via a coupling device 14 firmly connected. The wave 13 can by means of the engine 20 around a longitudinal axis L are driven in rotation around the tool 11 also around the longitudinal axis L to rotate. The front shaft part is at the tool end 13a via a first roller bearing arrangement 28 radial with a first radial bearing rigidity C1 stored. In the area of the coupling device 14 is the wave 13 by means of a second roller bearing arrangement 33 stored. The front shaft part 13a is about the second rolling bearing arrangement 33 and / or the coupling device 14 supported radially in such a way that the clutch device 14 subsequent end of the front shaft part 13a with a second radial bearing rigidity C2 is supported. The second radial bearing rigidity C2 is at most 80% or at most 50-65% or at most 30% or at most 20% of the first radial bearing stiffness C1 . As a result, with otherwise the same geometry of the spindle arrangement 10 and the tool 11 reach significantly higher cutting depths.

Reference list

10th

Spindle arrangement

11

Tool

12th

Spindle housing

12a

first spindle housing part

12b

second spindle housing part

13

wave

13a

front shaft part

13b

rear shaft part

14

Coupling device

14a

front coupling part

14b

rear coupling part

20

engine

21

rotor

22

stator

23

Tool holder

24th

Recording room

28

first rolling bearing arrangement

29

first rolling bearing

30th

second rolling bearing

33

second rolling bearing arrangement

34

front roller bearing

35

rear roller bearing

36

third roller bearing arrangement

37

third rolling bearing

40

Damping element

41

Damping ring

42

Groove

44

Outer ring

45

Inner ring

46

Rolling elements

47

Damping element of the coupling device

50

cover

A

amplitude

C1

first radial bearing rigidity

C2

second radial bearing rigidity

Approx

radial initial stiffness

Cb

reduced radial bearing rigidity

D1

first outer diameter

D2

second outer diameter

Fr

Radial force

L

Longitudinal axis

S

gap

W1

first lines of action

W2

second lines of action

W3

third lines of action

W4

fourth lines of action

Claims (13)

Spindle arrangement (10) for a machine tool, with a shaft (13) which is rotatably mounted about a longitudinal axis (L) in a spindle housing (12) and has a front shaft part (13a) and a rear shaft part (13b) which are detachably connected to one another by means of a coupling device (14) are, with a motor (20) which is drivingly coupled to the rear shaft part (13b), the front shaft part (13a) being arranged at its end opposite the coupling device (14) for connection to a tool (11), with a first roller bearing arrangement (28) which rotatably supports the front shaft part (13a) on the spindle housing (12) at the end region opposite the coupling device (14), the first roller bearing arrangement (28) having a first radial bearing stiffness radially to the longitudinal axis (L) ( C1), with a second roller bearing arrangement (33), which rotatably supports a front roller bearing (34), which rotates the front shaft part (13a) adjacent to the coupling device (14) on the spindle housing (12), and a rear roller bearing (35), which holds the rear shaft part ( 13b) rotatably mounted on the spindle housing (12) adjacent to the coupling device (14), wherein the second roller bearing arrangement (33) is designed in such a way or wherein the second roller bearing arrangement (33) and the coupling device (14) are designed such that the front shaft part (13a) immediately following the coupling device (14) radially to the longitudinal axis (L) is supported with a second radial bearing rigidity (C2) which is a maximum of 80% of the first radial bearing rigidity (C1), and wherein the second roller bearing arrangement (33) and / or the coupling device (14) has at least one damping element (40, 47) which is set up to dampen a radial movement of the shaft (13). Spindle arrangement after Claim 1 , characterized in that at least one damping element (40) of the at least one damping element (40, 47) between the front roller bearing (34) and the spindle housing (12) and / or between the rear roller bearing (35) and the spindle housing (12) is arranged. Spindle arrangement after Claim 1 or 2nd , characterized in that at least one damping element (47) of the at least one Damping element (40, 47) is arranged between a front coupling part (14a) of the coupling device (14) connected to the front shaft part (13a) and a rear coupling part (14b) of the coupling device (14) connected to the rear shaft part (13b). Spindle arrangement according to one of the preceding claims, characterized in that there is a third roller bearing arrangement (36) which rotatably supports the rear shaft part (13b) on the spindle housing (12), the motor (20) between the second roller bearing arrangement (33) and the third roller bearing arrangement (36) on the rear shaft part (13b). Spindle arrangement after Claim 4 , characterized in that the motor (20) is arranged coaxially to the longitudinal axis (L) between the second roller bearing arrangement (33) and the third roller bearing arrangement (36). Spindle arrangement after Claim 4 or 5 , characterized in that the rear roller bearing (35) of the second roller bearing arrangement (33) and a roller bearing (37) of the third roller bearing arrangement (36) are arranged such that intersection points of the lines of action (W3, W4) with the longitudinal axis (L) in Direction of the longitudinal axis (L) is on the side facing the other roller bearing (35, 37). Spindle arrangement according to one of the preceding claims, characterized in that the number of rolling elements (46) of the front rolling bearing (34) and / or of the rear rolling bearing (35) is selected such that the second radial bearing rigidity (C2) is achieved. Spindle arrangement according to one of the preceding claims, characterized in that the first roller bearing arrangement (28) has two roller bearings (29, 30) which are arranged such that intersection points of the lines of action (W1, W2) with the longitudinal axis (L) in the direction of The longitudinal axis (L) is outside the axial space between these roller bearings (29, 30) of the first roller bearing arrangement (28). Spindle arrangement according to one of the preceding claims, characterized in that an outer diameter (D2) of the front roller bearing (34) of the second roller bearing arrangement (33) is smaller than an outer diameter (D1) of the first roller bearing arrangement (28). Spindle arrangement according to one of the preceding claims, characterized in that each of the roller bearing arrangements (28, 33, 36) has at least one roller bearing (29, 30, 34, 35, 37) designed as an inclined bearing. Spindle arrangement according to one of the preceding claims, characterized in that all rolling bearings (39, 30, 34, 35, 37) are designed as angular bearings. Spindle arrangement according to one of the preceding claims, characterized in that the second radial bearing stiffness (C2) is a maximum of 55-65% or a maximum of 20-30% of the first radial bearing stiffness (C1). Spindle arrangement according to one of the preceding claims, characterized in that the spindle housing (12) has two spindle housing parts (12a, 12b), the first spindle housing part (12a) enclosing the front shaft part (13a), and the second spindle housing part (12b) the rear one Shafts part (13b) encloses.

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