Method for gear cutting with subsequent chamfering

Abstract

The present invention relates to a method for gear cutting, in which, in a gear cutting machine controlled by a control device, teeth are formed or machined on a workpiece clamped on a workpiece spindle arranged in a first machine position by means of a gear cutting tool rotated on a first tool spindle, and subsequently, during the same workpiece clamping operation or clamping operation of the machined toothed workpiece on a workpiece spindle arranged in a second machine position, cutting of the chamfer tool on the tooth edge of the tooth flank of the workpiece toothing is performed by the synchronous rotation of the workpiece and a workpiece-specific chamfering tool rotated by the second tool spindle and by a feed operation between the chamfering tool and the workpiece. a chamfer is formed by cutting with a cutting edge, wherein during the chamfering, the axial distance between the rotation axis of the workpiece and the rotation axis of the chamfering tool is not more than half the pitch of the workpiece tooth, the crossed-axis angle between the tool rotation axis and the workpiece rotation axis and / or the crossed-axis angle between the tool rotation axis and a surface perpendicular to the end face of the workpiece adjacent to the machined tooth edge differs from 90° by not more than 12°, preferably not more than 8°, in particular not more than 4°, the main directional component of the feed motion extends in the direction of the tool rotation axis, and the cutting edge has a directional component in the direction of the rotation axis of the chamfering tool that is greater in the chamfering part at least in an area of ​​half the tooth height of the workpiece tooth than in a directional component in a plane of rotation perpendicular thereto.

Description

[Technical Field]

[0001] The present invention relates to a method for gear cutting with subsequent chamfering. [Background technology]

[0002] It is well known in the art to chamfer the teeth at the tooth edges after machining them. For example, if the end face of a gear serves as a flat cutting or defining surface in subsequent operations, its flatness is disrupted by burrs. Furthermore, after hardening, the burrs pose a risk of breaking off when the gear later rotates in a gear mechanism, causing damage to the tooth flank or gear mechanism components. Apart from this, such burrs also pose a risk of injury when handling the teeth or toothed workpiece. If only the burrs are removed and the tooth edges themselves are not machined, there is a risk that the tooth edges will glass harden due to overcarbonization during hardening and then break under stress.

[0003] To address this drawback, numerous different chamfering methods have been developed. In the method disclosed in EP 1279127 A1, workpiece material in the tooth edge region is removed by a chamfering wheel that rolls in tooth-engagement with the workpiece. Secondary burrs (material buildup) generated during this so-called rolling deburring or rolling pressure deburring must also be removed afterward. German Patent No. 102009018405 A1 teaches how such secondary burrs can be properly removed.

[0004] As an alternative to this chamfering by plastic pressing, it is possible to form the chamfer on the tooth edge by cutting.According to German Patent No. 102009019433 A1, a substantially cylindrical machining tool with at least one cutting edge is clamped in a tool spindle.

[0005] German Patent No. 102013012797 (A1) discloses a method for working in a cutting mode in which a chamfering wheel is substantially similar to a skiving wheel, but an additional tilt angle is set based on the standard configuration of the skiving engagement. The axial distance set here corresponds in magnitude to the sum of the workpiece radius and the tool radius, and the chamfering can be performed with a feed motion primarily parallel to the workpiece axis or integrated into the chamfering tool through a special design of the chamfering tool. The chamfering process described in the non-patent document "Advances in Manufacturing Engineering and Materials," pages 18-26, also works with a feed motion parallel to the workpiece axis, where a workpiece-specific chamfering tool simultaneously machines both tooth edges of the tooth space, with the cutting speed component parallel to the workpiece axis directed toward the axial tooth center of one edge and away from the axial tooth center of the other edge.

[0006] Another cutting chamfering process (so-called "chamfer milling") using a workpiece-specific chamfering tool, the profile of which is designed so that when the chamfer milling blade passes through the tooth space of the workpiece tooth, the workpiece tooth is completely chamfered on both sides of the tooth space, is disclosed in German Patent No. 102013015240 (A1). These "chamfer milling cutters" appear similar to hobs, with overlapping flight circles in the same profile area. A further cutting chamfering operation more closely oriented towards gear hobbing is described in German Patent No. 102018001477.

[0007] According to a similar principle to the "chamfer cutting mirror" disclosed in German Patent No. 102013015250 (A1), there is also a fly-cutter-like removal of tooth edges, which is used, for example, to create bevels for the teeth of gear trains, where a rotary fly-cutter, for example realized in the form of an end mill, is aligned with the tool rotation axis of the rotary fly-cutter at an angle relative to the tool rotation axis so that the tooth flank of the workpiece tooth is machined in a single pass through the machining zone by a cutting process parallel to the final geometric shape to be generated. Such a process is described, for example, in the non-patent document T. Bausch, "Innovative Zahnradfertigung", Expert-Verlag, 3rd edition, p. 323.

[0008] The method disclosed in German Patent No. 102014218082 (A1) is similar to the gear skiving chamfering process of German Patent No. 102013012797 (A1), but the beveled axis configuration is already structurally integrated into the gear cutting machine.

[0009] Yet another chamfering technique has become known from German Patent No. 102018108632 (A1), in which a pin milling cutter is moved along the tooth edge by machine axis movements, the chamfering technique being particularly suitable for leading edges that cannot be easily reached using "chamfer cutting mills" or hob-type tools due to interference contours on the workpiece.

[0010] WO 2019 / 017248(A1) proposes using a pressing process such as roller pressure deburring, which shifts the weight of secondary burr generation from the tooth flank towards the end face.

[0011] With regard to the arrangement, it is known from EP 1 495 824 A2 to arrange the machining tool used to chamfer the tooth edges on the same shaft as the hob used to manufacture the workpiece teeth. Summary of the Invention [Problem to be solved by the invention]

[0012] All of these chamfering techniques have advantages and disadvantages. The present invention is based in particular on the object of providing a gear cutting process with subsequent chamfering that achieves a satisfactory combination of suitability for machining workpieces with interfering contours and simplicity of process design.

[0013] The object of the present invention is to provide a method for gear cutting, in which, in a gear cutting machine controlled by a control device, teeth are formed or machined on a workpiece clamped on a workpiece spindle arranged in a first machine position by means of a gear cutting tool rotated on a first tool spindle, and subsequently, during the same workpiece clamping operation or clamping operation of the machined toothed workpiece on a workpiece spindle arranged in a second machine position, cutting the tooth edges of the tooth flanks of the workpiece teeth with the cutting edge of the chamfering tool by means of synchronous rotation of the workpiece and a workpiece-specific chamfering tool rotated by the second tool spindle and by means of a feed operation between the chamfering tool and the workpiece. wherein during chamfering, the axial distance between the rotation axis of the workpiece and the rotation axis of the chamfering tool is not more than half the pitch of the workpiece tooth, the cross-axis angle between the tool rotation axis and the workpiece rotation axis and / or the cross-axis angle between the tool rotation axis and a surface perpendicular to the end face of the workpiece adjacent to the machined tooth edge differs from 90° by not more than 12°, preferably not more than 8°, in particular not more than 4°, the main directional component of the feed motion extends in the direction of the tool rotation axis, and in particular the cutting edge has a directional component in the direction of the rotation axis of the chamfering tool that is greater in the chamfering section at least in an area half the tooth height of the workpiece tooth than in a directional component in a plane of rotation perpendicular thereto.

[0014] This combination of cross-axis angle adjustment, feed motion and cutting position configuration, and axial distance limitation ensures that the chamfer can be machined in a continuous process, even in the vicinity of interference contours, thus also saving time, unlike in the case of predominantly axial feed motion, or in the case of chamfering with pin milling cutters, where the chamfering tool is moved along the tooth edge as in form milling cutters.

[0015] In a preferred method design, tooth edges other than the one chamfered by the chamfering tool in the same tooth space are chamfered by an additional chamfering tool which is rotationally driven by a third tool spindle.

[0016] This variant has the advantage that due to the additional chamfering tool, the coupling of the machining of both tooth edges of the tooth space is eliminated, and therefore the machining offset due to the (even if small) time difference in the sequential machining of both tooth edges, mediated via the workpiece rotation, is eliminated.

[0017] In this connection, it is preferred that the directional component of the cutting speed parallel to the workpiece axis is directed away from the axial center (i.e., away from the side) of the workpiece tooth (towards the machined front face) when chamfering with the chamfering tool and / or the additional chamfering tool, preferably when chamfering with both tools, thereby reducing the risk of secondary burrs being formed on the tooth face.

[0018] In a further preferred embodiment, the chamfering is controlled by the same control device as the gear cutting with the gear cutting tool. This design is also considered worthy of protection, regardless of the feed movement issue. Therefore, the invention also provides a method for gear cutting, in which, in a gear cutting machine controlled by a control device, teeth are formed or machined on a workpiece clamped on a workpiece spindle arranged in a first machine position by means of a gear cutting tool rotated on a first tool spindle, and subsequently, during the same workpiece clamping operation or clamping operation of the machined toothed workpiece on a workpiece spindle arranged in a second machine position, a cutting edge of the chamfering tool is applied to the tooth flank of the workpiece toothing by means of a synchronous rotation of the workpiece and a workpiece-specific chamfering tool rotated on a second tool spindle, and by means of a feed movement between the chamfering tool and the workpiece. a chamfer formed by cutting, wherein during the chamfering, the axial distance between the rotation axis of the workpiece and the rotation axis of the chamfering tool is not more than half the pitch of the workpiece tooth, the crossed-axis angle between the tool rotation axis and the workpiece rotation axis and / or the crossed-axis angle between the tool rotation axis and a surface perpendicular to the end face of the workpiece adjacent to the machined tooth edge differs from 90° by not more than 12°, preferably not more than 8°, in particular not more than 4°, and in particular the cutting blade has, at least in the chamfer part in the region of the tooth head of the workpiece tooth, a directional component in the direction of the rotation axis of the chamfering tool that is greater than the directional component in a rotation plane perpendicular thereto, and the chamfering is controlled by the same control device as for the gear cutting with the gear cutting tool.

[0019] Thus, the control device is not a separate control device that receives external inputs solely for the purpose of chamfering, but rather already has internally the control parameters of the previous tooth manufacturing or machining, including any setting changes made within the batch, which makes the chamfering method safer and more reliable.

[0020] In this connection, it is advantageous if at least one control parameter of the chamfer is incorporated into the chamfer in response to a change in the control parameter of the gear cutting by the gear cutting tool, which increases the flexibility of the method.

[0021] In a further preferred embodiment, the control parameters will influence the course of the transition line between the tooth flank and the chamfer during chamfering, taking into account the tolerances to be removed in the subsequent hard finishing operation compared to the final shape of the workpiece toothing.

[0022] This improves the final accuracy of the chamfer after subsequent hardening and hard finishing by taking into account in advance how the transition line will change in its course due to hard finishing. Preferably, the transition line is set to be parallel to the leading edge surface in the final shape after hard finishing. The workpiece-specific profiling of the chamfer tool can be determined, for example, by inverse transformation of a given transition line (after chamfering) with a given axial kinematics.

[0023] In a further preferred embodiment, the chamfering will be performed in the continued presence of cooling and / or lubricating fluid resulting from the hobbing operation with the hobbing tool. This is preferably a semi-wet machining process in the sense that no additional lubricant / fluid is used during the chamfering, but the cooling and / or lubricating fluid from the previous hobbing operation still wets the workpiece.

[0024] In a further preferred embodiment, the burrs generated by the chamfering are removed using an additional burr removal device, in particular a brush. Such secondary burrs may occur especially in the case of helically toothed workpieces with larger helix angles. In combination with the aforementioned preferred uniform cutting direction component parallel to the workpiece axis during chamfering, a burr-free chamfered workpiece can be provided simply by using a brush acting especially in the area of ​​the end face.

[0025] In a further preferred embodiment, the control device will control the chamfer to produce a course of the transition line between the chamfer and the side that deviates from parallelism to the end face. The different course is preferably controlled so that parallelism is restored after hard finishing, as described above. This aspect of the invention is also considered advantageous and worthy of protection, regardless of the course of the feed motion.

[0026] The present invention therefore also provides a method for gear cutting, in which, in a gear cutting machine controlled by a control device, teeth are formed or machined on a workpiece clamped on a workpiece spindle arranged in a first machine position by means of a gear cutting tool rotatably driven on a first tool spindle, and subsequently, during the same workpiece clamping operation or clamping operation of the machined toothed workpiece on a workpiece spindle arranged in a second machine position, cutting edges of the tooth flanks of the workpiece teeth with the cutting edge of the chamfering tool by synchronous rotation of the workpiece and a workpiece-specific chamfering tool rotatably driven by the second tool spindle and by a feed movement between the chamfering tool and the workpiece. a chamfer is formed by chamfering the workpiece, during which the axial distance between the rotation axis of the workpiece and the rotation axis of the chamfering tool is not more than half the pitch of the workpiece tooth, the cross-axis angle between the tool rotation axis and the workpiece rotation axis and / or the cross-axis angle between the tool rotation axis and a surface perpendicular to the end face of the workpiece adjacent to the machined tooth edge differs from 90° by not more than 12°, preferably not more than 8°, in particular not more than 4°, and in particular the cutting edge has, at least in the chamfer part in the region of the tooth head of the workpiece tooth, a directional component in the direction of the rotation axis of the chamfering tool that is greater than the directional component in the plane of rotation perpendicular thereto, and the control device controls the chamfer to generate a course of the transition line between the chamfer and the flank that deviates from parallelism to the end face.

[0027] In one possible embodiment, the crossing axis angle will be adjustable, in particular via a rotary axis, and in particular will be numerically controlled.

[0028] In a further advantageous embodiment, the second and third tool spindles are carried by a common carrier, in particular having at least two degrees of freedom of movement.

[0029] The chamfering described above is applicable to external teeth. However, the invention also contemplates chamfering internal teeth. For this purpose, the chamfering tool is preferably provided with a spindle head having an angle gear mechanism.

[0030] Variants of this method for internal gear cutting are also considered to be advantageous and worthy of protection in themselves, regardless of the question of how the feed movement should / can be performed. The invention therefore also provides a method for gear cutting, in which, in a gear cutting machine controlled by a control device, internal teeth are formed or machined on a workpiece clamped on a workpiece spindle arranged in a first machine position by means of a gear cutting tool rotatably driven on a first tool spindle, and subsequently, in the same workpiece clamping operation or clamping operation of the machined internally toothed workpiece on a workpiece spindle arranged in a second machine position, a synchronous rotation of the workpiece and a workpiece-specific chamfering tool rotatably driven by a second tool spindle, and between the chamfering tool and the workpiece. a chamfer is formed by cutting the tooth edge portion of the tooth flank of the internal tooth of the workpiece with a cutting blade of a chamfering tool by a feed motion of the chamfering tool, wherein during chamfering, the axial distance between the rotation axis of the workpiece and the rotation axis of the chamfering tool is not more than half the pitch of the workpiece tooth portion, and the crossed-axis angle between the tool rotation axis and the workpiece rotation axis and / or the crossed-axis angle between the tool rotation axis and a surface perpendicular to the end face of the workpiece adjacent to the machined tooth edge differs from 90° by not more than 12°, preferably not more than 8°, in particular not more than 4°, and in particular the cutting blade has a directional component in the direction of the rotation axis of the chamfering tool that is greater than the directional component in a plane of rotation perpendicular to the rotation axis.

[0031] The variant of internal gear cutting defined in this way can be combined with the above-mentioned version of the chamfer.

[0032] A preferred design in this regard provides the device with two degrees of freedom of movement for the chamfer, specifically two linear degrees of freedom of movement, one of which has a principal component parallel to the workpiece rotation axis and one of which has a principal component radial to the workpiece rotation axis, preferably achieved via a cross-carriage arrangement.

[0033] The method can be performed on a horizontal machine (with a horizontal workpiece rotation axis). In this case, linear axes for moving the main machining tool on the one hand and for positioning the chamfering tool on the other hand are preferably provided on both sides of the workpiece rotation axis. Furthermore, the chamfering tool preferably has its tip pointing toward the chamfering side of the linear motion axis, which preferably extends parallel to the workpiece rotation axis. In a further preferred embodiment, the internally toothed workpiece is clamped on the workpiece spindle, and the clamp provides an axial distance between the axial end side of the internal toothing closest to the clamp and the spindle end area, which is located within the internal toothing in a projection perpendicular to the workpiece rotation axis and faces axially toward the axial end side of the internal toothing away from the clamp. In this way, the chamfering head carrying the chamfering tool can be moved axially deeper into the internal toothing to chamfer the end face of the internal toothing closest to the clamp without changing the clamp.

[0034] A direct drive can be used as the rotary drive of the chamfering tool. Preferably, however, the indirect drive and the drive force transmission are realized by a gear mechanism, in particular an angle gear mechanism. A simple belt transmission is also conceivable.

[0035] When implemented using a vertical machine (vertical workpiece rotation axis), a variant is also conceivable in which the machining head for the main machining process carries the machining head for the chamfering process in a piggyback manner. In this variant, the chamfering head accepts all movement axes available to the main machining head, which can also be used as positioning axes, feed axes, and even feed axes. In a further preferred variant, the chamfering tool is further arranged so that it can be displaced perpendicular to its rotation axis relative to the main machining head. The displacement axis can be implemented as an NC axis or a simple adjustment axis, for example, to move the machining tool between a retracted position and a working position, and has, for example, a main direction component parallel to the rotation axis of the main machining tool. However, a defined angle setting of this movement axis relative to the tool rotation axis of the main machining is also considered, so that the chamfering is performed in a configuration in which the tool rotation axis of the main machining tool and the workpiece axis are at an axis crossing angle selected sufficiently large to prevent collisions between the main machining tool and the workpiece during the chamfering process. This variant can also be considered in combination with a variant in which the chamfering tool is movable relative to the main machining head.

[0036] In other designs, the chamfering head may be provided and positionable independently from the main machining head of a vertical machine as well.

[0037] With regard to the device, the object is to provide an apparatus for gear cutting, in which, in a gear cutting machine controlled by a control device, teeth are formed or machined on a workpiece clamped on a workpiece spindle arranged in a first machine position by means of a gear cutting tool rotated on a first tool spindle, and subsequently, in a clamping operation of the same workpiece or the machined toothed workpiece on a workpiece spindle arranged in a second machine position, cutting of the chamfering tool on the tooth edge of the tooth flank of the workpiece toothing is performed by means of a synchronous rotation of the workpiece and a workpiece-specific chamfering tool rotated by a second tool spindle and by means of a feed operation between the chamfering tool and the workpiece. The chamfer is formed by cutting with a cutting edge, and during chamfering, the axial distance between the workpiece rotation axis and the rotation axis of the chamfering tool is not more than half the pitch of the workpiece tooth, the cross-axis angle between the tool rotation axis and the workpiece rotation axis and / or the cross-axis angle between the tool rotation axis and a surface perpendicular to the end face of the workpiece adjacent to the machined tooth edge differs from 90° by not more than 12°, preferably not more than 8°, in particular not more than 4°, the main directional component of the feed motion extends in the direction of the tool rotation axis, and in particular, the cutting edge has a directional component in the direction of the chamfering tool rotation axis that is greater than the directional component in the plane of rotation perpendicular to it, at least in the chamfering portion in an area of ​​half the tooth height of the workpiece tooth.

[0038] As already mentioned above with respect to the method according to the invention, the device can be designed so that tooth edges different from those of the same tooth space chamfered by the chamfering tool are chamfered by an additional chamfering tool which is rotationally driven by a third tool spindle. This variant can also be implemented regardless of whether one directional component of the feed movement predominates or which directional component predominates.

[0039] The control device for the chamfering may be the same control device that also controls the gear cutting by the gear cutting tool. This variant may also be implemented regardless of whether one directional component of the feed motion predominates or which directional component predominates.

[0040] Likewise, in a preferred embodiment, the control device will be designed / programmed to control the chamfer to produce a course of transition line between the chamfer and the side that deviates from parallelism to the end face. This variant can also be implemented regardless of whether one directional component of the feed motion predominates or which directional component predominates.

[0041] The gear cutting machine used to carry out the method preferably also performs the main gear cutting operation itself. Transport of the gear cutting machine to the chamfering area is preferably via a loading system such as a gantry loader, as will be described in more detail elsewhere. The advantages of the gear cutting machine according to the invention are clear from the above description of the method according to the invention.

[0042] The number of cutting edges of the chamfering tool is preferably not more than 4, in particular only 2 or only 1. The working diameter of the chamfering tool relative to the pitch circle is preferably between 1 and 4 pitches of the tooth to be chamfered. [Brief explanation of the drawings]

[0043] Further features, details and advantages of the invention will be found in the following description, taken in conjunction with the accompanying drawings. [Figure 1] FIG. 1 is a diagram showing a gear cutting machine. [Figure 2] FIG. 2 is a plan view schematically illustrating the chamfering area of ​​the gear cutting machine of FIG. 1. [Figure 3a] FIG. [Figure 3b] FIG. [Figure 4] FIG. [Figure 5] FIG. 1 is a simple schematic diagram of an internal tooth chamfer. [Figure 6] FIG. 1 shows a part of a skiving machine with a chamfering unit. [Figure 7]FIG. 7 shows the chamfering unit of FIG. 6 in machining mode. [Figure 8a] 10A-10C show another gear skiving machine with a chamfering unit as a whole and in different positions, respectively; [Figure 8b] 10A-10C show another gear skiving machine with a chamfering unit as a whole and in different positions, respectively; [Figure 8c] 10A-10C show another gear skiving machine with a chamfering unit as a whole and in different positions, respectively; DETAILED DESCRIPTION OF THE INVENTION

[0044] In the embodiment described herein with reference to FIG. 1, a gear cutting machine 500 is provided, which is shown diagrammatically in the form of a horizontal machine. In FIG. 1, a workpiece spindle rotation axis C is diagrammatically shown on the side of the main machining station 50, and a workpiece spindle rotation axis C2 is diagrammatically shown on the side of the chamfering station 100. Both stations 50, 100 belong to the gear cutting machine 500, symbolized in FIG. 1 by a common frame 200, which may also be designed as a common machine bed. A reloading system 80, shown only diagrammatically in FIG. 1, can pick up a workpiece from the main workpiece spindle, which defines the (main) workpiece spindle axis C, and transfer it to the workpiece spindle 10 associated with the (chamfering) workpiece spindle axis C2. The transfer thus takes place within the gear cutting machine 500, with the two workpiece spindle axes C and C2 running parallel and horizontally, preferably coaxially. A partition 75 may be provided between the main machining station 50 and the chamfering station 100. The main machining station 50 is also provided with a tool head (not shown) with corresponding movement options for gear cutting. In this case, the main machining station 50 is designed for gear skiving, but the invention is not limited thereto. For example, gear hobbing or gear shaping can also be performed.

[0045] 2 shows a chamfering station or chamfering area 100 of a gear cutting machine 500 in a possible embodiment. On the workpiece side, a workpiece spindle 10 is shown with a workpiece spindle axis C2 extending in the Z direction (here horizontally). Opposite the workpiece spindle 10, a tailstock 11 can be used if a preferably shaft-shaped workpiece is to be machined.

[0046] The linear guide for the tool carriage 7 is represented by two rails 8 and extends parallel to the Z axis. Two tool heads 21, 22 are arranged on the carriage 7 and are axially movable relative to the linear carriage 7 via further linear guides along a (radial) axis X having linear movement axes X1 and X2. The linear guides are represented by rails 81, 82. The rotation axes of the chamfering tools are indicated by B1 and B2 in FIG. 2, and the chamfering tools are indicated by 1 and 2. In this embodiment, the one or more linear axes X (X1, X2) are also horizontal. The representation in FIG. 2 therefore corresponds to a top view. A centering sensor 3 is provided between chamfering tool 1 and chamfering tool 2, which here is equipped with a pneumatic drive (not shown). Using the centering sensor 3, the position of the tooth space of the tooth to be chamfered can be determined in a known manner.

[0047] 2 also shows a vertical axis Y, which together with the linear axes Z and X form a right-angled tripod. In the embodiment shown, the spindle axes C2, B1, and B2 are at the same height level and there is no further axis of movement in the Y direction. However, in other implementations, a vertical carriage can be provided that allows the devices 7, 8 to be moved vertically.

[0048] In this implementation, according to a preferred embodiment, the workpiece spindle axis C2 is horizontal as already explained, but in principle a vertical machine can also be provided, in which case the linear movement X can still be used as a radial movement for the teeth clamped on the workpiece spindle 10.

[0049] In the variant described with reference to Figure 2, a first chamfering tool 1 is used to chamfer the tooth edges (particularly also in the tooth root area) on one tooth flank, for example the left flank, and a second chamfering tool 2 is used for chamfering on the other tooth flank, for example the right flank. The rotation directions of the spindle axes B1 and B2 are preferably controlled in opposite directions here, and the controller is represented by the reference number 99 in Figure 2. Furthermore, the rotation direction is adjusted so that the tooth edges to be chamfered are cut from the inside out, away from the axial tooth center, in order to avoid burrs on the sides of the tooth flank.

[0050] The drive spindle can be any spindle arrangement known to those skilled in the art, such as a high-frequency spindle. The interface between the chamfering tool and the spindle can be designed as an HSK interface. A two-rail linear guide is also shown as an example. Specifically, only one rail, e.g., a dovetail-shaped rail, on which an appropriately shaped shoe slides, can be provided. The gear cutting machine reloading system 80 shown in FIG. 1 transfers the workpiece, which has been geared in the main station (main machining area) 50, to the workpiece spindle 10 in the chamfering area 100 of the gear cutting machine 500 without changing the axial direction of the workpiece during transport.

[0051] 3a and 3b show the feed motion during chamfering. Thus, in one mode of operation, the controller 99 is designed to control the feed motion purely radially. The chamfering tool decreases the radial distance to the tooth being chamfered during machining from radial position B to radial position B.

[0052] In the operating mode shown in Figure 3b, the controller 99 is designed to perform a feed motion by superimposing a radial movement X and an axial movement Z, where the radial motion component dominates.

[0053] In both cases, by adjusting the feed motion, chamfering is possible even near the interfering contours, symbolized by the asterisks in Figure 3. If necessary, a purely axial feed motion can also be considered, especially if no interfering contours are taken into account, or even a superimposed feed motion with a predominantly axial component. At least one of these feed motion concepts can be stored in the controller 99 and used.

[0054] FIG. 4 again shows the machining operation of the chamfering tool 1 in a perspective view. In this embodiment, the workpiece rotation axis C2 and the tool rotation axis B1 are at an axis crossing angle of 90° due to their parallelism with the mutually perpendicular axes Z and X. In addition, in the illustrated embodiment, the axial distance of the rotation axes is 0, i.e., the extension of the rotation axis B1 intersects with the extension of the rotation axis C2. In other embodiments, smaller axial distances and / or smaller deviations of the axis crossing angle from 90° can also be provided. In the illustrated variant, the front surface 6 of the toothing 4 extends orthogonally to the workpiece rotation axis C2. In the case of an inclined end face, instead of orthogonality of the tool rotation axis to the Z axis, orthogonality to the surface normal of the inclined end face can be provided. To adjust the axis crossing angle, the tool head (20, 21, 22) can have an additional rotation axis (not shown in FIG. 2).

[0055] The workpiece rotation axis C2 and the tool rotation axis B1 are synchronously controlled by the controller 99, so that the cutting blade 15 of the chamfering tool 1 is brought into cutting engagement with the tooth edge 5 of the workpiece tooth 4 and forms a chamfer thereon. The position of the cutting blade 15 is realized in a workpiece-specific manner so that at the final machining position when the feed operation on the tooth is completed, in place of the tooth edge 5, the predetermined chamfer shape of the currently formed chamfer is achieved.

[0056] In this case, the transition line between the tooth flank and the chamfer may preferably not yet be formed parallel to the end face 6, as desired, but deviates from the end face 6, such that such a parallel transition line only occurs after subsequent hard finishing of the workpiece toothing 5 to its final dimensions.

[0057] In the variant described with reference to Figure 2, the chamfering tools 1 and 2 are formed so that only one tooth edge 5 is chamfered, and the tooth edge on the opposite side of the tooth space is not chamfered. However, in another embodiment, the chamfering tool (with tool rotation axis B) can also machine both tooth edges. In that case, the "double chamfering tool configuration" shown in Figure 2 is no longer required, and only one chamfering tool head (20) with tool rotation axis (B) is required.

[0058] Insofar as secondary burrs are still formed by the chamfering, for example on the front surface 6, these can be removed by a deburring unit not shown, for example a brush or brush device.

[0059] The controller 99 controls the entire gear cutting machine 500, i.e., the main machining area 50 as well as the chamfering area 100. Changes in the machine axis settings during the main machining area 50 may therefore be checked internally within the control system to determine whether corrections are required for chamfering, and if necessary, correction settings for the chamfering method may be made internally and automatically within the control system. In principle, however, the chamfering described above could also be performed in a separate chamfering station.

[0060] The chamfering technique described above has been described as an example for chamfering external teeth, but is also suitable for chamfering internally toothed workpieces (FIG. 5). For this purpose, the tool head / chamfering tool enters the space defined by the contour of the internal teeth as seen in its projection onto the workpiece rotation axis, for example, by the corresponding projection of the spindle head, which is preferably designed with an angular gear mechanism. The axis of movement can be double, as shown in FIG. 2, or single for the chamfering tool.

[0061] In the following, using Figures 6 to 8, a specific design of a gear cutting machine for manufacturing / machining internal teeth and equipped with a chamfering unit operating according to one or more aspects as described above will be described.

[0062] As can be seen in Figure 6, which shows the relevant details of the gear skiving machine 600, this gear skiving machine 600 is designed as a so-called horizontal machine with a horizontally arranged workpiece spindle rotation axis C6. On the workpiece side, a workpiece 602 in the form of an internal tooth is clamped to the workpiece spindle 610.

[0063] On the tool side, a skiving wheel 601 having a tool rotation axis B6 is provided as the main machining tool. The skiving wheel 601 is arranged on a tool head 604 in the usual way and produces or machines an internally toothed workpiece 602 in the gear skiving process. The tool head 604 is linearly movable along a linear axis Y6, and a carriage arrangement provided for realizing this linear movement Y6 is arranged swivelably with a pivot axis A6. The support structure enabling this pivoting around axis A6 is provided in the form of a cross carriage, along which two further linear movement axes X6 and Z6 are realized. In the design described by way of example, axis Z6 extends parallel to workpiece spindle axis C6, and axis X6 is a radial infeed axis parallel to pivot axis A6.

[0064] The foreground of Figure 6 shows the chamfering unit 640, which is also realized as a cross-carriage arrangement. A first carriage 641 can move along a linear movement axis Z4, which runs parallel to the workpiece rotation axis C6, along a guide rail arrangement provided on the machine support side. The first carriage 641 forms a guide rail arrangement for the carrier 642 carried by it, which can move along a further radial axis X4 relative to the first carriage 641, which axis X4 is perpendicular to axis Z4. A chamfering head 643 carried by a second carriage 642 can be positioned relative to the internally toothed workpiece 602 via these two axes X4, Z4.

[0065] In the position shown in FIG. 6 , the chamfering tool 644, mounted on the chamfering tool head 643 so that it can be driven to rotate about its axis, is inactive, and the skiving operation is performed by the skiving wheel 601. Depending on the dimensions of the tool-side machining tools (601, 641), skiving and chamfering may be performed simultaneously depending on the dimensions of the workpiece. For the sizes specifically shown here, continuous machining is provided. The chamfering operation is shown in FIG. 7 , which shows further details of the gear cutting machine 600 at an enlarged angle. In the illustration in FIG. 7 , the chamfering tool 644 chamfers the tooth edge on the axial end side facing the tool of the internally toothed workpiece 602. Machining of the tooth edge on the axial end side facing away from the tool is performed under a changed relative positioning between the chamfering tool 641 and the workpiece 602. To do this, the chamfering tool 641 is first disengaged using the X4 axis. It is then moved axially along the Z4 axis to the level of the other axial end side, and then fed back using the X4 axis for chamfering. In addition to positioning, the X4 axis and / or the Z4 axis may also be used as a feed axis during chamfering.

[0066] 8a shows a further exemplary embodiment in the form of another gear cutting machine 800, which is also configured as a skiving machine with a skiving wheel S. The gear cutting machine 800 is designed as a vertical machine with a vertical workpiece rotation axis, here designated as C8, and the internally toothed workpiece itself is not shown, only the workpiece table.

[0067] On the tool side, the tool rotation axis is designated B8 and the tool head is designated 78. The latter is swivelable about a pivot axis A8 and can be moved tangentially by a swivel carriage 76 (axis Y8). The swivel unit realizing the pivoting about axis A8 can also be moved vertically about a linear axis Z8 and linearly towards or away from the worktable about a radial axis X8. The skiving wheel S therefore has three linear NC axes and one rotary NC axis for positioning, infeed and advancement during skiving for positioning relative to a workpiece clamped on the workpiece table.

[0068] In this exemplary embodiment, the tool head 78 carries the chamfering unit 88 in a piggyback manner. This means that the chamfering head 843, like the skiving head 78, can move over all movement axes X8, Z8, A8, Y8. Similar to the configuration shown in FIG. 7, the chamfering head 843, carrying the chamfering tool 844, is again axially movable relative to the tool head 78 via the movement axis Z84. This axis may be an NC axis also used for the chamfering process, or a pure positioning axis, via which the chamfering head 843 can move from a retracted first position ( FIG. 8b ), in which the internal tooth cutting process is not impeded by the skiving wheel S, to an extended second position ( FIG. 8c ), in which the chamfering process is not impeded by the skiving wheel S as a tool-side interference contour. In this configuration, the main machining with the skiving wheel S is performed at a cross-axis angle relative to the workpiece rotation axis, and the chamfering is not performed at the same cross-axis angle, but rather either with axes Z84 and C8 parallel to the axis or at a smaller cross-axis angle compared to the cross-axis angle of the skiving.

[0069] In this exemplary embodiment, the chamfering unit 80 is arranged on the workpiece-facing side of the main machining head 78, although a lateral arrangement is also conceivable. Accordingly, the orientation of the rotation axis of the chamfering tool 844 may preferably be radial, i.e., extend parallel to the X8 axis, but may also be tangential, i.e., parallel to the Y8 axis (while remaining laterally engaged, i.e., disposed radially relative to the engagement area). To machine external teeth using the gear cutting machine 800, the chamfering tool 844 will have its tip pointing toward the workpiece rotary table and will therefore be positioned opposite to the illustration in FIG. 8c. For this purpose, the chamfering tool head 843 is either pivoted by 180° relative to its mounting in the chamfering unit 80 or removed and remounted with an orientation changed by 180°. Also contemplated is an axis crossing angle formed by the structural relative arrangement between the axis B8 and the axis Z84, so that when Z8 and Z84 are set parallel, the skiving wheel S is turned by turning around this axis crossing angle without risk of collision.

[0070] In all the variants of Figures 6 to 8, the chamfering tool can be driven by a small direct drive, but an indirect drive connected via a gear mechanism or belt transmission to the rotating shaft of the unit, which is coaxial with the workpiece rotation axis, is preferred.

[0071] The present invention is not limited to the details and embodiments set forth in the above description of the drawings, but rather individual features of the above specification and the following claims may be essential, individually or in combination, to implement the invention in its various embodiments.

Claims

1. A method for gear cutting, in a gear cutting machine (500) controlled by a control device, wherein teeth are formed or machined on a workpiece clamped on a workpiece spindle positioned at a first machine position by a gear cutting tool rotated on a first tool spindle, and subsequently, in the same workpiece clamping operation on a workpiece spindle (10) positioned at a second machine position or in the clamping operation of the machined toothed workpiece, the chamfering tool cuts the tooth edge (5) of the tooth surface of the workpiece teeth by the synchronous rotation of the workpiece and a workpiece-specific chamfering tool (1) for the workpiece rotated on the second tool spindle, and by a feed operation (V) between the chamfering tool and the workpiece. A method comprising: forming a chamfer by cutting with a cutting blade (15); during chamfering, the axial distance between the rotation axis of the workpiece and the rotation axis of the chamfering tool is less than or equal to half the pitch of the workpiece teeth; the axial intersection angle between the tool rotation axis and the workpiece rotation axis, and / or the axial intersection angle between the tool rotation axis and a surface perpendicular to the end face (6) of the workpiece adjacent to the machined tooth edge is 12° or less, preferably 8° or less, and particularly 4° or less is different from 90°; the main directional component of the feed motion (V) extends in the direction of the tool rotation axis; and the cutting blade has a directional component in the chamfered portion in a region of at least half the tooth height of the workpiece teeth that is greater in the direction of the rotation axis of the chamfering tool than in the directional component in the rotation plane perpendicular thereto.

2. The method according to claim 1, wherein a tooth edge different from the tooth edge of the same tooth groove that has been chamfered by the chamfering tool is chamfered by an additional chamfering tool that is rotationally driven by a third tool spindle.

3. The method according to claim 2, wherein when chamfering with the chamfering tool and / or the additional chamfering tool, preferably when chamfering with both tools, the directional component of the cutting speed parallel to the workpiece axis is directed away from the axial center of the workpiece teeth.

4. The method according to claim 1, wherein the chamfer is controlled by the same control device as the gear cutting process performed by the gear cutting tool.

5. The method according to claim 4, wherein at least one control parameter of the chamfer is incorporated into the chamfer in response to a change in the control parameter of the gear cutting process by the gear cutting tool.

6. The method according to claim 5, wherein the control parameter affects the course of the transition line between the tooth surface and the chamfer during chamfering, taking into account tolerances to be removed in subsequent hard finishing operations compared with the final shape of the workpiece tooth portion.

7. The method according to claim 1, wherein the chamfering is performed in the continuous presence of a cooling and / or lubricating fluid resulting from the gear cutting process by the gear cutting tool.

8. The method according to claim 1, wherein burrs formed by chamfering are removed by an additional deburring device, particularly a brush.

9. The method according to claim 1, wherein the control device controls the chamfer to generate a course of a transition line between the chamfered portion and the side surface that deviates from parallelism with respect to the end face.

10. The method according to claim 1, wherein the axis intersection angle is variably adjustable, particularly via a rotating axis, and particularly under NC control.

11. The method according to claim 2, wherein the second tool spindle and the third tool spindle are supported by a common carrier having at least two degrees of freedom of motion.

12. The method according to claim 1, wherein the machined and chamfered tooth portion is an internal tooth.

13. A gear cutting apparatus, a gear cutting machine controlled by a control device, wherein teeth are formed or machined on a workpiece clamped on a workpiece spindle positioned at a first machine position by a gear cutting tool rotationally driven on a first tool spindle, and subsequently, in the same workpiece clamping operation on a workpiece spindle positioned at a second machine position or the clamping operation of the machined toothed workpiece, the cutting edge of the tooth surface of the workpiece teeth is cut by the cutting blade of the chamfering tool through synchronous rotation of the workpiece and a workpiece-specific chamfering tool rotationally driven by the second tool spindle, and through a feed operation between the chamfering tool and the workpiece. A chamfer is formed, and during chamfering, the axial distance between the rotation axis of the workpiece and the rotation axis of the chamfering tool is less than or equal to half the pitch of the workpiece teeth, the axial intersection angle between the tool rotation axis and the workpiece rotation axis, and / or the axial intersection angle between the tool rotation axis and a surface perpendicular to the end face of the workpiece adjacent to the machined tooth edge is 12° or less, preferably 8° or less, and particularly 4° or less is different from 90°, the main directional component of the feed motion extends in the direction of the tool rotation axis, and in particular, the cutting blade has a directional component in the direction of the rotation axis of the chamfering tool that is greater in the chamfered portion in a region of at least half the tooth height of the workpiece teeth than in the directional component in the rotation plane perpendicular thereto thereto.

14. The apparatus according to claim 13, comprising a control device designed and programmed to control the method according to claim 1.

15. A gear cutting machine having a workpiece spindle positioned at a first machine position, a first tool spindle for rotationally driving a gear cutting tool for forming or machining gears on a workpiece clamped on the workpiece spindle, and the chamfering apparatus according to claim 13.

16. The gear cutting machine according to claim 15, further comprising a coaxial first workpiece spindle shaft and a second workpiece spindle shaft, and a linear motion shaft extending parallel to the first workpiece spindle shaft and the second workpiece spindle shaft for a reloading system that transfers a workpiece from the first workpiece spindle to the second workpiece spindle.

Images