Gear cutting device, tool head and gear cutting machine

Abstract

An apparatus 100 for gear cutting using a rotary machining tool 150 is disclosed. The apparatus comprises a motor spindle 130 with a drive motor 134 and a motor spindle shaft 133 drivable by the drive motor 134 and capable of driving the machining tool 150. The apparatus further comprises a mounting structure 120 for releasably mounting the apparatus on a work spindle of a tool head. The mounting structure 120 is designed such that the tool axis B is parallel to the work spindle axis when the apparatus is mounted on the work spindle of a tool head. An apparatus is also disclosed that allows the machining tool 150 to be connected in a simple manner to a counter bearing 140. For this purpose, the counter bearing comprises a hollow shaft 143. A clamping mandrel 160 comprises a first clamping area and a second clamping area arranged at different positions along the longitudinal axis of the clamping mandrel. The clamping mandrel is introduced into a longitudinal bore 156 of the machining tool 150 through the hollow shaft along the tool axis.

Description

[Technical field]

[0001] The present invention relates to an apparatus for machining a gear using a rotary machining tool, a tool head equipped with the same, and a gear cutting machine equipped with the same. [Background technology]

[0002] In continuous generating gear grinding, a toothed workpiece is machined in generating engagement (also known as rolling engagement) with a rotating grinding worm. The grinding worm is held in a tool head that includes a work spindle. At one end, the grinding worm is connected to the work spindle which drives the grinding worm in rotation. At the other end of the grinding worm, a counter bearing may be provided. However, especially in the case of grinding worms that are relatively short in relation to their diameter, the counter bearing is often omitted. This makes it easier and quicker to replace the grinding worm.

[0003] In recent years, the purpose of machining gears with small modules, such as those used in electric drives, arises more and more frequently. For this purpose, it may be useful to use a relatively small but long grinding worm. Also, for machining gears whose interference shapes are adjacent in the axial direction of the gear, a small grinding worm diameter may be required. For small and long grinding worms, a one-sided bearing is disadvantageous, and therefore the grinding worm should be supported at both ends. The same applies for other small but long machining tools.

[0004] In the prior art there are many examples of tool heads in which the machining tools are supported at both ends. In order to be able to exchange the machining tools despite the fact that they are supported at both ends, it has been proposed in the prior art to provide a permanently mounted drive spindle and a removable or movable counter-bearing. An example with a movable counter-bearing is described in DE 10 200 43 336. However, such a solution may be disadvantageous in terms of the positioning accuracy of the counter-bearing and the rigidity of the tool head.

[0005] Further problems arise if a relatively small grinding worm is to be used in a gear cutting machine that is originally designed for grinding worms, which has a correspondingly large work spindle of a rather large diameter and, if applicable, an equally large counter bearing. Collisions between the work spindle or the counter bearing and the workpiece can then occur. It can also happen that the tool interface of such a large work spindle is not suitable for connecting to a small machining tool, or that the work spindle does not reach the desired speed.

[0006] US Pat. No. 5,399,363 discloses an apparatus including a tool holder for a hobbing tool and a fastener for mounting on a milling head of a universal milling machine having at least five axes. A gearbox transmits the rotational movement of the work spindle of the machine tool to the hobbing tool to drive the hobbing tool. In this way, existing universal milling machines, which are not themselves designed for hobbing, can be used to perform the hobbing process. However, this apparatus has some drawbacks. For example, hobbing requires very accurate synchronization of the tool rotation with the workpiece rotation. This requirement is difficult to meet with a gearbox. Secondly, the axis of rotation of the hobbing tool is perpendicular to the axis of rotation of the milling head. Therefore, this arrangement is not suitable for use in conventional gear cutting machines. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] European Patent Application No. 0516596 [Patent Document 2] European Patent Application No. 2216118 Summary of the Invention

[0008] In a first aspect, it is an object of the present invention to provide an apparatus which enables relatively small machining tools, in particular tools for use in generating processes (also known as rolling tools), such as grinding worms, to be used in gear cutting machines whose tool heads are not designed to directly receive such small machining tools.

[0009] This object is solved by a device having the features of claim 1. Further embodiments are defined in the dependent claims.

[0010] Thus, there is disclosed an apparatus for machining a gear using a rotary tool having a first end and a second end. The apparatus comprises: a motor spindle including a drive motor and a motor spindle shaft drivable by the drive motor, the motor spindle configured to generate rotation of the motor spindle shaft about the tool axis; a motor spindle, the motor spindle shaft configured to be connected at a first end thereof to the machining tool for driving the machining tool in rotation about a tool axis using a drive motor; a mounting structure for releasably mounting the apparatus to a work spindle of a tool head, the work spindle being configured to generate rotation of a work spindle shaft about a work spindle axis to drive a tool in rotation about the work spindle axis; The motor spindle is connected to a mounting structure; The mounting structure is configured such that when the device is mounted on the work spindle of the tool head, the tool axis is parallel to the work spindle axis. Equipped with.

[0011] A device suitable for being connected to the work spindle of the tool head and having a driven shaft formed separately from the work spindle for driving a machining tool is also referred to below as an "auxiliary spindle unit". The auxiliary spindle unit according to the invention is configured to be connected to the work spindle of the tool head such that the tool axis is parallel to the work spindle axis, so that essentially the same machining kinematics can be used for machining the workpiece as if the machining tool were clamped directly to the work spindle. By providing the auxiliary spindle unit with an independent motor spindle, the machining tool can be driven at an appropriate speed, regardless of the limitations of the work spindle. In addition to this, if the machining tool is a machining tool for machining by a generating method, the presence of a motor spindle allows a more accurate synchronization between the rotational movement of the machining tool and the rotational movement of the workpiece than if the drive is provided from the work spindle via a gearbox or a toothed belt drive.

[0012] In order to ensure that the tool axis extends parallel to the work spindle axis after the auxiliary spindle unit is attached to the work spindle, it is advantageous if the mounting structure has an at least partially annular (i.e. partially annular or completely annular) area configured to surround the work spindle (in particular a housing area of ​​the work spindle, which may be arranged adjacent to the tool interface of the work spindle), the at least partially annular area defining an annular axis (ring axis), which annular axis extends parallel to the tool axis. However, other designs of the mounting structure that ensure that the tool axis is parallel to the work spindle axis are also possible, such as hearth serrations, arc teeth, zero point clamping systems, or conical connections between the auxiliary spindle unit and the work spindle. Thus, many different designs of the mounting structure are possible to ensure that the tool axis is parallel to the work spindle axis after the auxiliary spindle unit is attached to the work spindle.

[0013] In particular, when an auxiliary spindle unit is used for machining with the generating method, it is advantageous if the auxiliary spindle unit also comprises a rotation measurement system for detecting the rotational position (rotation angle) of the spindle shaft about the tool axis. The rotational position of the spindle shaft detected in this way can be transmitted by the rotation measurement system to a machine controller, which establishes the necessary synchronization between the rotational movement of the machining tool and the rotational movement of the workpiece in order to maintain the rolling coupling.

[0014] The auxiliary spindle unit may be equipped with a balancing system, for example a single-plane or two-plane balancing system, however, the auxiliary spindle may also be operated without a balancing system.

[0015] The auxiliary spindle unit may further include a counter bearing configured to rotatably mount a machining tool at its second end, making the auxiliary spindle unit particularly suitable for machining tools that are long relative to their diameter.

[0016] To ensure good rigidity of the auxiliary spindle unit, it is advantageous if the motor spindle and the counter bearing are rigidly connected to the mounting structure.

[0017] Nevertheless, to make it possible to easily change the machining tools, The counter bearing has a hollow shaft that can rotate about the tool axis; The apparatus includes a mandrel (also referred to as an arbor) defining a longitudinal axis; The mandrel has a first clamping region and a second clamping region disposed at different positions along a longitudinal axis of the mandrel; The mandrel is insertable along the tool axis through the hollow shaft into the longitudinal bore of the machining tool such that the first clamping area is capable of clamping connection with the hollow shaft of the counter-bearing and the second clamping area is capable of clamping connection with the machining tool, thereby supporting the machining tool in the counter-bearing. The design is particularly advantageous.

[0018] This design allows the machining tool to be easily replaced by loosening the clamping connection and retracting the mandrel in the hollow shaft of the counter-bearing from the machining tool, thus allowing easy removal of the machining tool. At the same time, the use of the mandrel allows for a particularly flexurally strong connection between the machining tool and the counter-bearing.

[0019] Such a design is not only advantageous in an auxiliary spindle unit, but can also be employed in a tool head without an auxiliary spindle unit. In this regard, the invention also relates in more general terms to an apparatus for machining gears using a rotary machining tool having a first end and a second end, comprising: a motor spindle having a drive motor and a motor spindle shaft drivable by the drive motor and configured to be connected at a first end thereof to the machining tool for driving the machining tool in rotation about a tool axis; a counter-bearing configured to rotatably mount a rolling tool at a second end thereof, the counter-bearing including a hollow shaft rotatable about a tool axis; a mandrel defining a longitudinal axis; Equipped with The mandrel has a first clamping region and a second clamping region disposed at different positions along a longitudinal axis of the mandrel; The mandrel is insertable along the tool axis through the hollow shaft into the longitudinal bore of the machining tool such that the first clamping area is capable of clamping connection with the hollow shaft of the counter-bearing and the second clamping portion is capable of clamping connection with the machining tool, thereby supporting the machining tool in the counter-bearing. An apparatus is provided.

[0020] The device can be designed as an actual tool head or, as explained above, as an auxiliary spindle unit. If the device is designed as a tool head, the aforementioned motor spindle is the work spindle of the tool head. The spindle can then be mounted on a carrier together with a counter-bearing. In particular, both the work spindle and the counter-bearing can be rigidly mounted on the carrier. In particular, the carrier can be designed as a shift slide, which is then displaceably arranged on a base body. The base body can be designed as a swivel body which is mounted on the tool carrier of the gear cutting machine so as to swivel.

[0021] Regardless of whether the device is configured as an actual tool head or as an auxiliary spindle unit, the mandrel may be configured to provide a clamping connection with a press fit in at least one of the two clamping areas with a clamping force acting radially outwards. The press-fitted radially acting connection compensates for the length tolerances of all parts. If different machining tools are mounted, the difference in length between the mounting flanges of these machining tools is not significant in this system. The purely radially acting press-fit connection ensures the connection axially and radially and does not introduce undesired axial distortions.

[0022] The two clamping areas may have the same or different outer diameters, in particular the outer diameter of the first clamping area for connection to the hollow shaft of the counter bearing may be larger than the outer diameter of the second clamping area for connection to the machining tool.

[0023] The counter bearing may have no drive or may be part of a second motor spindle, which allows the machining tool to be driven on both sides.

[0024] In an advantageous embodiment, the mandrel acts as a hydraulically expandable mandrel in at least one of the two clamping regions. The design of at least one of the clamping regions as a hydraulically expandable mandrel allows a stable connection between the processing tool and the counter bearing in a particularly simple manner. The functional principle of a hydraulically expandable mandrel is known per se from the prior art. In particular, a hydraulically expandable mandrel comprises at least one expansion sleeve, which defines at least one clamping chamber, preferably a plurality of clamping chambers distributed radially outward in the longitudinal and / or circumferential direction. The clamping chambers can be hydraulically pressurized, whereby the expansion sleeve is expanded radially outward in the associated clamping region, generating a clamping force acting radially outward. Preferably, the associated clamping region has two axially spaced clamping points, at each of which at least one clamping chamber is arranged. In this way, an optimal bending stiffness can be achieved.

[0025] Preferably, the mandrel acts as a hydraulically expanding mandrel in both clamping regions. For this purpose, preferably one or more pressurizable clamping chambers are provided in each of the two clamping regions.

[0026] However, instead of a hydraulically expanding mandrel, the mandrel can also be designed as a mechanical mandrel, and it is also possible to use a mandrel which is designed as a hydraulically expanding mandrel in the first clamping area and as a mechanical mandrel in the second clamping area, or vice versa.

[0027] If the mandrel is designed as a mechanical mandrel in at least one of the two clamping regions, the mandrel may have a clamping sleeve in at least one of the two clamping regions, which can be radially expanded by mechanical action, similar to a hydraulically expandable mandrel. However, it is also possible for the mechanical mandrel to be designed in another way, for example by means of a clamping setting known per se for hollow shank taper connections, to generate a clamping connection in the clamping region in question. The clamping force generated in this way does not necessarily have to act radially outward.

[0028] If the mandrel is designed as a hydraulically expandable mandrel in at least one clamping region, the hydraulically expandable mandrel may be actuated mechanically or hydraulically in order to generate hydraulic pressure in the hydraulically expandable mandrel, with which the clamping connection is generated. If the hydraulically expandable mandrel is actuated hydraulically, the device may include a hydraulic turn inlet in the region of the counter bearing in order to apply external hydraulic pressure to the hydraulically expandable mandrel. In this way, the clamping connection can be made and released in an externally controlled manner. In particular, this facilitates an automated tool change.

[0029] To further facilitate the tool change, the device may comprise an actuator configured to automatically insert the mandrel into the longitudinal bore of the machining tool along the tool axis and remove the mandrel again from the longitudinal bore when the first and second clamping connections are released, the actuator may for example be a hydraulic, pneumatic or electric actuator.

[0030] Of course, the device may further comprise a machining tool, in particular a machining tool for machining by a generating method, in particular a grinding worm or a gear hob, in which case the machining tool is preferably mounted on the motor spindle instead of the work spindle, i.e. a first end of the machining tool is then connected to the motor spindle shaft for driving the machining tool to rotate about the tool axis.

[0031] The invention further provides a tool head including a work spindle and an auxiliary spindle unit of the type described above, the mounting structure of the auxiliary spindle unit being connected to the work spindle such that the tool axis is parallel to the work spindle axis.

[0032] As already explained above, such a tool head may also include a base body and a shift slide displaceable along a shift direction relative to the base body, the work spindle then being arranged on the shift slide.

[0033] Finally, the invention also provides a gear cutting machine comprising an apparatus of the type described above, at least one workpiece spindle for driving the workpiece in rotation about a workpiece axis, and a machine controller, the machine controller being optionally configured to establish a rolling coupling between the rotation of the machining tool and the rotation of the workpiece.

[0034] Preferred embodiments of the present invention are described below with reference to the drawings, which are for illustrative purposes only and are not to be construed as limiting. [Brief description of the drawings]

[0035] [Figure 1] FIG. 1 is a perspective view of an auxiliary spindle according to one embodiment. [Diagram 2] FIG. 2 is a vertical longitudinal section through the auxiliary spindle of FIG. 1, the cutting plane including the tool axis. [Diagram 3]FIG. 3 is a central longitudinal cross-sectional view of the rolling tool. [Figure 4] FIG. 4 is a central longitudinal cross-sectional view of a hydraulic expansion mandrel. [Diagram 5] FIG. 5 shows a tool head according to a first embodiment having an auxiliary spindle of FIG. [Figure 6] FIG. 6 is a diagram showing a machine tool equipped with the tool head shown in FIG. [Figure 7] FIG. 7 is a perspective view of a tool head according to the second embodiment. [Figure 8] FIG. 8 is a horizontal longitudinal section through the tool head of FIG. 7, the cutting plane including the tool axis. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] <Auxiliary spindle unit> 1 and 2 show an auxiliary spindle unit 100 according to one embodiment of the present invention.

[0037] The auxiliary spindle unit 100 includes a carrier 110 to which a mounting structure 120 is rigidly connected. The mounting structure 120 is used to mount the auxiliary spindle unit 100 to a work spindle of a tool head, as described in more detail below. The mounting structure 120 is annular in shape and thereby defines a ring axis R extending through the center of the toroid.

[0038] The auxiliary spindle unit 100 further comprises a motor spindle 130 and a counter bearing 140, each of which is rigidly connected to the carrier 110. Between the motor spindle 130 and the counter bearing 140 a tool 150 in the form of a grinding worm is arranged. The tool 150 is driven at one end by the motor spindle 130 to rotate about a tool axis B. At the other end it is rotatably supported by the counter bearing 140. The tool axis B extends parallel to the ring axis R.

[0039] The motor spindle 130 is designed as a direct drive in a manner known per se. It has a housing 131 in which a total of four rolling bearings 132 are accommodated. A spindle shaft 133 with a tool interface 135 is rotatably mounted in the rolling bearings 132. An electric drive motor 134 serves to directly drive the spindle shaft 133. The rolling bearings 132 are arranged on either side of the drive motor 134 in a manner known per se. The two rolling bearings located between the drive motor 134 and the tool interface 135 form axially fixed bearings in a manner known per se, i.e. the area of ​​the spindle shaft 133 located in these bearings and close to the tool interface 135 is axially fixed in these rolling bearings relative to the tool axis B. The other two rolling bearings form axially fixed bearings. The other two rolling bearings form axially floating bearings, i.e. the areas of the spindle shaft 133 located in these bearings are able to move axially to a certain extent relative to these bearings. This serves in particular to allow for thermal expansion of the spindle shaft. The rotational measurement system 136 serves to detect the rotational position of the spindle shaft 133 about the tool axis B.

[0040] The counter bearing 140 has a housing 141 in which two rolling bearings 142 are received. A hollow shaft 143 is rotatably supported in the rolling bearings 142. The two rolling bearings 142 form an axially floating bearing for the hollow shaft 143, i.e. the hollow shaft 143 can move to a certain extent along the tool axis B due to the axial play of the two rolling bearings 142.

[0041] In Fig. 3, the tool 150 is shown alone. It has a mounting flange 151 which supports a grinding wheel 153 with a worm-shaped profile. A precision shaft nut 152 secures the grinding wheel 153 to the mounting flange 151. At its end facing the motor spindle 130, the mounting flange 151 has a known short taper attachment 155 with a surface contact for centrally connecting the mounting flange 151 to a tool interface 135 of the motor spindle 130, which has a correspondingly complementary external taper with a surface contact. A screw 154 serves to axially secure the mounting flange 151 to the tool interface 135. At its end facing the counter bearing 140, the mounting flange 151 has a centrally located cylindrical longitudinal bore 156.

[0042] Instead of a short taper connection fixed by means of a screw, other types of connections between the mounting flange 151 and the tool interface 135 are also possible, as is well known from the prior art. In particular, it is possible to have a hollow tapered shaft (HSK) connection or a Capto™ connection, as is widely used in mechanical engineering. In a manner known per se, the tool interface 135 may further comprise a clamping device, not shown, which can be locked and released in a controlled manner to facilitate the exchange of the machining tool 150. The screw 135 can then be omitted accordingly.

[0043] The hydraulically expanding mandrel 160, shown alone in FIG. 4, serves to connect the mounting flange 151 to the counter bearing 140. It has a cylindrical base body 161 in which a line system 164 for hydraulic fluid is formed, shown only diagrammatically. The hydraulically expanding mandrel has two clamping areas 160a, 160b along its longitudinal axis L. In each of these clamping areas, the base body 161 is surrounded by a thin-walled expansion sleeve 162a, 162b. Each expansion sleeve 162a, 162b defines a number of clamping chambers 163a, 163b radially outward. A clamping piston 165, axially displaceable by a clamping screw 166, is used to generate hydraulic pressure that is transmitted to the clamping chambers 163a, 163b via the line system 164. As a result, the expansion sleeves 162 a , 162 b expand radially in the area of ​​the clamping chambers 163 a , 163 b and thus establish a radial clamping connection with the hollow shaft 143 of the counter-bearing 140 and with the mounting flange 151 of the machining tool 150 .

[0044] The axial positions where the clamping chambers 163a, 163b are located are also referred to as clamping points. In this embodiment, the hydraulically expanding mandrel 160 has two clamping points in each of the two clamping regions 160a, 160b, totaling four clamping points. This helps to achieve high bending stiffness. However, it is also conceivable to have, for example, only one clamping point in each of the two clamping regions 160a, 160b.

[0045] Although the two clamping areas 160a, 160b in the embodiment of FIG. 4 have the same outer diameter, these outer diameters may also be different. In particular, the outer diameter of the first clamping area 160a may be selected to be larger than the outer diameter of the second clamping area 160b. This may be particularly advantageous when using tools whose mounting flanges have a longitudinal bore with a particularly small aperture. Within the clamping areas, the outer diameter may in principle vary from clamping point to clamping point, in particular decreasing in stages in the insertion direction.

[0046] At one end, the hydraulically expandable mandrel 160 projects axially from the counter-bearing 140. At this end, the hydraulically expandable mandrel 160 has an end piece 167 with an annular groove 168 on its outer periphery, the function of which will be explained in more detail below in connection with the second embodiment of the tool spindle.

[0047] To accommodate the machining tool 150 between the motor spindle 130 and the counter-bearing 140, the hydraulically expanding mandrel 160 is first fully withdrawn from the counter-bearing 140, and the machining tool 150 is inserted between the motor spindle 130 and the counter-bearing 140. The machining tool 150 is then connected to the tool interface 135 of the motor spindle 130. This attachment may be performed via the counter-bearing 140. The hydraulically expanding mandrel 160 is then axially inserted through the hollow shaft 143 of the counter-bearing 140 into the longitudinal bore 156 of the mounting flange 151, such that the first clamping area 160a of the hydraulically expanding mandrel 160 rests in the hollow shaft 143 of the counter-bearing 140 and the second clamping area 160b rests in the longitudinal bore 156. The hydraulic expansion mandrel 160 is then radially clamped to the hollow shaft 143 of the counter-bearing 140 and to the mounting flange 151. To remove the machining tool 150 again, the procedure is reversed.

[0048] By using a hydraulically expanding mandrel 160 to connect the processing tool 150 to the counter-bearing 140, a simple and at the same time bending-rigid connection can be realized, even if the counter-bearing 140 is rigidly connected to the carrier 110, i.e. if the counter-bearing cannot be moved for tool changes. The counter-bearing 140 rigidly connected to the carrier 110 has the advantage in terms of rigidity compared to a movable counter-bearing.

[0049] <First embodiment of tool head> In Fig. 5 a tool head 200 according to a first embodiment is shown. The tool head comprises a basic body 210 designed as a pivot body. A shift slide 220 is arranged on the basic body 210 for being displaceable along a shift direction Y. The shift direction Y runs parallel to the tool axis B. For the controlled displacement of the shift slide 220 on the basic body 210 a Y drive 221 is used.

[0050] The work spindle 230 is rigidly mounted on the shift slide 220. In principle, it is possible to mount a machining tool directly on the work spindle 230 in order to drive it in rotation about the work spindle axis B'. For this purpose, the work spindle 230 has a suitable tool interface. However, if the tool has a small diameter, direct clamping of the machining tool on the work spindle 230 is problematic, since a collision of the workpiece with the work spindle 230 can easily occur.

[0051] Therefore, in this embodiment, the auxiliary spindle unit 100 described above is mounted on the work spindle 230. For this purpose, the mounting structure 120 of the auxiliary spindle unit 100 surrounds the front area of ​​the housing of the work spindle 230, which is located adjacent to the tool interface of the work spindle 230, thus fixing the auxiliary spindle unit 100 to the work spindle 230. As a result, the tool axis B runs parallel to and at a distance from the work spindle axis B'. A media interface 170, shown only diagrammatically, supplies the auxiliary spindle unit 100 with the required media, such as compressed air and power, and allows measurement data to be exchanged with the sensors of the auxiliary spindle unit 100.

[0052] The motor spindle 130 of the auxiliary spindle unit 100 can be made significantly more compact than the work spindle 230 arranged directly on the shift slide 220 due to the small size of the machining tool 150 and the associated low stock removal rate. The significantly more compact design of the motor spindle 130 of the auxiliary spindle unit 100 significantly reduces the risk of collision with the workpiece. At the same time, the motor spindle 130 and the counter bearing 140 can be specifically optimized for machining tasks with small machining tools. For example, the tool speed of a small machining tool may be significantly higher than the tool speed of a large machining tool, and accordingly the motor spindle 130 and the counter bearing 140 of the auxiliary spindle unit 100 may be designed for a higher tool speed than the work spindle 230 of the shift slide 220.

[0053] 6 shows an example of the entire gear cutting machine 1 having the tool head 200 of the first embodiment. The gear cutting machine 1 has a machine base 10 on which a tool carrier 20 is disposed so as to be displaceable along a horizontal feed direction X. A Z-slide 30 is disposed on the tool carrier 20 so as to be displaceable along a vertical direction Z. The tool head 100 described above is disposed on the Z-slide 30, and the tool head 100 can rotate with respect to the Z-slide 30 around a horizontal rotation axis A extending parallel to the feed direction X.

[0054] Also arranged on the machine bed 10 is a workpiece spindle 40 on which a workpiece 41 is clamped. The workpiece spindle 40 can be driven to rotate about a workpiece axis C extending parallel to the Z direction.

[0055] The gear cutting machine also comprises a machine controller 50, which is symbolically shown only. The machine controller 50 takes over all control and monitoring tasks in the gear cutting machine. In particular, the machine controller establishes the correct rolling coupling between the rotation of the workpiece about the workpiece axis C and the rotation of the tool about the tool axis B for machining the workpiece 41. The machine controller 50 may for this purpose receive and evaluate signals from the rotation measurement system 136 of the motor spindle 130 and from the rotation measurement system of the workpiece spindle 40.

[0056] The illustrated gear cutting machine is to be understood as merely an example, and the invention is of course not limited to this example. In particular, gear cutting machine concepts are also conceivable in which two or more workpiece spindles are arranged on a movable carrier, and in which it is possible, for example, to machine a workpiece on one of the workpiece spindles and to exchange the machined workpiece for a blank on the other workpiece spindle, and further operations are carried out if necessary. Such gear cutting machine concepts are well known from the prior art.

[0057] <Second embodiment of the tool head> 7 and 8 show a tool head 200 according to a second embodiment. In this embodiment, the tool head 200 comprises a carrier 210, a shift slide 220, a Y drive 221, a work spindle 230 rigidly connected to the shift slide 220, and a counter bearing 240.

[0058] In contrast to the first embodiment, here the machining tool 150 is clamped directly to the work spindle 230 and supported on the counter-bearing 240, i.e. no auxiliary spindle unit is used. However, the connection between the machining tool 150 and the counter-bearing 240 is made in exactly the same way as the connection between the machining tool 150 and the counter-bearing 140 in the first embodiment, i.e. by means of a hydraulically expanding mandrel 160.

[0059] In particular, the counter-bearing 240 comprises a housing 241 in which two rolling bearings 242 are held, each of which is fitted with a hollow shaft 243. As in the first embodiment, the hydraulically expanding mandrel 160 extends through the hollow shafts 243 into a longitudinal bore of a mounting flange of the processing tool 150 and establishes a radial clamping connection with the hollow shafts 243 on the one hand and with the mounting flange on the other hand.

[0060] To enable the hydraulically expandable mandrel 160 to be moved automatically into and out of the mounting flange, the tool head has a linear actuator 250, which in this example is designed as a hydraulic cylinder 251 acting from both sides on a hydraulic piston 252 displaceable therein. However, other types of actuators are naturally conceivable, for example pneumatically or electrically operated actuators. Connected to the hydraulic piston 252 is an actuating arm 253 which engages in an annular groove 168 (see FIG. 4) on the periphery of the end piece 167 of the hydraulically expandable mandrel 160. The actuation of the actuator 250 thus causes the hydraulically expandable mandrel 160 to move axially.

[0061] In a further embodiment, the actuation arm 253 performs a double function by further comprising a hydraulic line, not shown in the drawings. In this way, hydraulic pressure can be applied to the hydraulically expandable mandrel 160 via the hydraulic turn inlet 245 in order to establish or release the clamp connection in a controlled manner. In such a further embodiment, the clamp screw 166 and, if necessary, even the clamp piston 165 may be omitted. Overall, a fully automated tool change can be achieved in this way without manual intervention on the hydraulically expandable mandrel 160.

[0062] For completeness, the design of the work spindle 230 is also briefly described below. It has a housing 231 in which several rolling bearings 232 are arranged. A work spindle shaft 233 is mounted on the rolling bearings 232 so that it can rotate about a work spindle axis B' and can be driven directly by a drive motor 234. A tool interface 235, shown here only in a very schematic manner, serves as a connection with a mounting flange of the tool 150. As already indicated in connection with the first embodiment, the tool interface 235 can be designed in any manner known per se, for example as an HSK connection according to ISO 12164-1:2001-12, as a steep taper connection according to DIN ISO 7388-1&2:2014-07 or as a Capto™ connection according to ISO 26623-1:2020. In this embodiment, the tool axis B coincides with the work spindle axis B'.

[0063] <Example of change> It is apparent from the above that various modifications are possible without departing from the scope of the invention as defined in the claims.

[0064] In particular, the invention can be used with tools for machining by generating processes, such as grinding worms or gear hobs, but also with machining tools with at least one form grinding wheel, including combination tools comprising at least one grinding worm in a common tool mandrel with at least one form grinding wheel. The tool may in particular be an abrasive tool, for example an abrasive grinding worm, or a combination tool with an abrasive grinding area.

[0065] An actuator like that in the second embodiment may of course also be provided in the auxiliary spindle unit according to the first embodiment, as well as the hydraulic turn inlet discussed above.

[0066] Although in the embodiments described above it is not assumed that the tool is additionally driven on the side of each counter-bearing 140, 240, the counter-bearings may be part of a second motor spindle in order to drive the tool on both sides. [Explanation of symbols]

[0067] 1 Gear cutting machine 10 Machine stand 20 Tool Carrier 30 Z-slide 40 Workpiece Spindle 41 Workpiece 50 Machine Controller 100 Auxiliary spindle unit 110 Career 120 Mounting structure 130 Motor Spindle 131 Housing 132 Rolling bearings 133 Spindle shaft 134 Drive motor 135 Tool Interface 136 Rotational Measurement System 140 Counter bearing 141 Housing 142 Rolling bearings 143 Hollow Shaft 150 Processing tools 151 Mount flange 152 Precision shaft nut 153 Grinding Wheel 154 Screw 155 Short taper attachment 156 Longitudinal Bore 160 Hydraulic expansion mandrel 160a first clamping region 160b Second clamping area 161 Base 162a, 162b Expansion sleeve 163a, 163b Clamp chamber 164 Line System 165 Clamp piston 166 Clamp screw 167 End parts 168 Circular Groove 170 Media Interface 200 Tool Head 210 Base 220 Shift Slide 221 Shift drive unit 230 Work Spindle 231 Housing 232 Rolling bearings 233 Spindle shaft 234 Drive motor 235 Tool Interface 240 Counter bearing 241 Housing 242 Rolling bearings 243 Hollow Shaft 245 Turnaround entrance 250 Actuator 251 Hydraulic Cylinder 252 Hydraulic Piston 253 Actuating Arm A Swivel Axis B Tool axis B´ Work spindle axis C Workpiece axis R ring axis X, Y, Z directions

Claims

1. An apparatus (100) for machining a gear using a rotary machining tool (150) having a first end and a second end, the apparatus (100) comprising: a motor spindle (130) having a drive motor (134) and a motor spindle shaft (133) drivable by the drive motor (134), the motor spindle (130) configured to generate rotation of the motor spindle shaft (133) about a tool axis (B), the motor spindle shaft (133) configured to be connected at its first end to the machining tool (150) to drive the machining tool to rotate about the tool axis (B); the device is configured as an auxiliary spindle unit for releasable attachment of a tool head (200) to a work spindle (230), the work spindle (230) being configured to generate a rotation of a work spindle shaft (233) about a work spindle axis (B') to drive the machining tool (150) or another tool to rotate about the work spindle axis, the apparatus (100) comprising a mounting structure (120) configured for releasably mounting the apparatus (100) to the work spindle (230); The motor spindle (130) is connected to the mounting structure (120); The mounting structure (120) is configured such that when the device (100) is mounted on the work spindle (230) of the tool head (200), the tool axis (B) is parallel to the work spindle axis (B'). The device, characterized in that

2. 2. The apparatus (100) of claim 1, wherein the mounting structure (120) comprises an at least partially annular region configured to surround the work spindle (230), the at least partially annular region defining a ring axis (R), the ring axis (R) being parallel to the tool axis (B).

3. 3. The apparatus (100) of claim 1 or 2, further comprising a rotational measurement system (136) for detecting the rotational position of the motor spindle shaft (133) about the tool axis (B).

4. 3. The apparatus (100) of claim 1 or 2, further comprising a counter bearing (140) configured to rotatably support the machining tool (150) at the second end thereof.

5. 5. The apparatus (100) of claim 4, wherein the motor spindle (130) and the counter bearing (140) are rigidly connected to the mounting structure (120).

6. 5. The apparatus (100) of claim 4, The counter bearing (140) comprises a hollow shaft (143) rotatable around the tool axis (B), The apparatus (100) comprises a mandrel (160) defining a longitudinal axis (L); the mandrel (160) comprises a first clamping region (160a) and a second clamping region (160b) disposed at different positions along the longitudinal axis (L) of the mandrel (160); the mandrel (160) is insertable along the tool axis (B) through the hollow shaft (143) into the longitudinal bore (156) of the machining tool (150) such that the first clamping area (160a) is capable of clamping connection with the hollow shaft (143) of the counter-bearing (140) and the second clamping area (160b) is capable of clamping connection with the machining tool (150) to support the machining tool (150) within the counter-bearing (140); The device.

7. An apparatus (100; 200) for machining a gear using a rotary machining tool (150) having a first end and a second end, the apparatus (100; 200) comprising: a motor spindle (130; 230) having a drive motor (134; 234) and a motor spindle shaft (133; 233) drivable by the drive motor (134; 234), the motor spindle shaft (133; 233) configured to be connected at its first end to the machining tool (150) for driving the machining tool (150) to rotate about a tool axis (B); a counter bearing (140; 240) configured to rotatably support the machining tool (150) at its second end; Equipped with the counter bearing (140; 240) comprises a hollow shaft (143; 243) rotatable around the tool axis (B), The apparatus (100; 200) comprises a mandrel (160) defining a longitudinal axis (L); the mandrel (160) comprises a first clamping region (160a) and a second clamping region (160b) disposed at different positions along the longitudinal axis (L) of the mandrel (160); the mandrel (160) is insertable through the hollow shaft (143; 243) along the tool axis (B) into the longitudinal bore (156) of the machining tool (150) such that the first clamping area (160a) is capable of clamping connection with the hollow shaft (143; 243) of the counter-bearing (140; 240) and the second clamping area (160b) is capable of clamping connection with the machining tool (150) to support the machining tool (150) within the counter-bearing (140; 240), The device, characterized in that

8. 8. The device of claim 7, wherein the first clamping area (160a) and / or the second clamping area (160b) are configured to establish a radially outwardly oriented clamping connection.

9. 9. The apparatus of claim 8, wherein the mandrels (160) in the first clamping area (160a) and / or the second clamping area (160b) are configured as hydraulically expanding mandrels.

10. 10. The device according to claim 9, wherein the device comprises a hydraulic turning inlet (245) in the region of the counter bearing (140; 240) for applying external hydraulic pressure to the hydraulically expandable mandrel.

11. 8. The apparatus of claim 7, further comprising an actuator configured to automatically insert the mandrel into the longitudinal bore of the machining tool along the tool axis with the first clamping connection and the second clamping connection released, and to remove the mandrel from the longitudinal bore again along the tool axis.

12. 10. The apparatus (100) of claim 1 or 7, further comprising the machining tool (150), wherein the first end of the machining tool (150) is connected to the motor spindle shaft (133) for driving the machining tool (150) for rotation about the tool axis (B).

13. 13. The device (100) according to claim 12, wherein the machining tool (150) comprises a tool for machining by a generating method, in particular a grinding worm.

14. A tool head (200), a work spindle (230); An apparatus according to claim 1 or 2; Equipped with The mounting structure (120) is connected to the work spindle (230) so that the tool axis (B) is parallel to the work spindle axis (B'). The tool head.

15. a substrate (210); a shift slide (220) displaceable along a shift direction (Y) relative to the base (210); Further provided with The tool head of claim 14, wherein the work spindle (230) is disposed on the shift slide (220).

16. A gear cutting machine, An apparatus according to claim 1 or 7; at least one workpiece spindle (40) for driving a workpiece (41) in rotation about a workpiece axis (C); a machine controller (50); Equipped with The machine controller (50) is preferably configured to establish a rolling coupling between the rotation of the machining tool (150) and the rotation of the workpiece (41). The gear cutting machine.

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