Method for tooth-cutting machining of at least one workpiece

Abstract

This invention discloses a method for toothing, particularly hard finishing, one or more workpieces using a toothed finishing tool with an indeterminate cutting edge, the finishing tool having a basic barrel shape, wherein the finishing tool and the workpiece rotate in a rolling coupling with each other, and the finishing tool moves in a feed direction parallel to the workpiece's axis of rotation during at least one toothing cut to machine the workpiece across its width. It is proposed that, between the machining of two workpieces and / or between two toothing cuts at one workpiece and / or during one toothing cut, the contact line between the finishing tool and the workpiece is selectively shifted on the finishing tool to utilize additional areas of the tool surface by changing the inclination angle between the finishing tool and the workpiece.

Description

Technical Field

[0001] This invention relates to a method for tooth machining, particularly hard finishing, of at least one workpiece using a finishing tool with an indeterminate cutting edge, the finishing tool having a basic barrel shape, and to a corresponding tooth-making machine. The workpiece may, in particular, be a workpiece with internal teeth. Background Technology

[0002] For the hard finishing of internal gear teeth, there are different continuous generating manufacturing methods. This is particularly relevant to:

[0003] Honing with corundum tools

[0004] - Generating grinding (Wälzschleifen) using corundum grinding worm gears.

[0005] Honing using dressing-free CBN tools

[0006] - Generating grinding using a dressing-free CBN grinding worm.

[0007] - Hard scraping using a generating scraper (a geometrically defined cutting edge).

[0008] The challenge is to manufacture as many parts as possible using cutting tools. Quality must be maintained within the required limits.

[0009] Methods using corundum tools (generating grinding, honing) allow for tool regrinding through dressing, thereby enabling the workpiece to regain the desired quality even after a manufacturing cycle up to the wear limit. However, dressing is time-consuming.

[0010] In hard scraping methods, due to the limited cutting edge, corresponding feed marks appear on the tooth surface, which may have a negative impact on load-bearing performance or noise performance.

[0011] Cutting tools with CBN can travel radially into the tooth (similar to the kinematics of honing) or axially through the tooth (generating grinding), similar to corundum tools. This eliminates the need for dressing time. However, it results in higher tooling costs.

[0012] It is known from generating grinding of externally toothed tools that the tool is moved in the direction of its axis of rotation between two tooth-making cuts and / or during a single tooth-making cut to utilize additional areas of the tool surface. This allows for better utilization of the tool surface. This is also known as displacement or a displacement strategy. However, for tooth machining of internal teeth using a finishing tool with a CBN-coated surface, which has a basic barrel shape, no similar solution exists to date. Here, the tool, in particular, cannot move in the direction of its axis of rotation due to its barrel shape.

[0013] Document US 8,382,560 B2 discloses such a finishing tool having a barrel-shaped basic shape and being used for continuous generating grinding.

[0014] Various documents have shown gear machining methods using a finishing tool with internal teeth, the finishing tool having a basic barrel shape, wherein the finishing tool and the workpiece rotate in a rolling coupling with each other, and the finishing tool moves through the workpiece in a feed direction parallel to the workpiece's axis of rotation in at least one tooth cutting operation, so as to machine the workpiece across its width.

[0015] This is achieved by utilizing a fixed contact path between the finishing tool and the workpiece, as well as by using a preset axial angle based on the geometry of the finishing tool and the workpiece, and a zero tilt angle between the workpiece and the finishing tool.

[0016] Therefore, in document EP 2 383 064 B1, the axis angle is set to a fixed value based on the crown size of the finishing tool. In document EP 2 460 625 B1, the axis angle is adjusted to fit the new diameter of the tool. Document EP 2 471 621 B1 proposes setting the axis angle based on the helix angle of the teeth of the workpiece and the tool. Here, the error in the actual position of the tool should be corrected based on the contour error measured at the workpiece.

[0017] Document EP 3 274 120 B1 illustrates a method for machining teeth on an internally toothed workpiece, wherein a combined tool is used, comprising a tool for hard scraping and a tool for honing, used sequentially for tooth machining.

[0018] Regardless of whether dressingable tools such as corundum tools or non-dressing tools such as CBN tools are used, tool wear is the decisive factor for the economics of the method. Summary of the Invention

[0019] Therefore, the object of the present invention is to provide an improved method for machining teeth on at least one workpiece by means of a finishing tool having a barrel-shaped basic shape.

[0020] The objective is achieved by the method according to the invention. Preferred designs of the invention are derived from the specification.

[0021] The well-established terminology of generating scraping (Wälzschälen) is used hereinafter to describe the invention, as described, for example, in EP 2 520 390 B2. In particular, the terms “axis angle,” “effective axis angle,” “common perpendicular,” and “angle of inclination,” in their common meanings for generating scraping, are used as described therein.

[0022] This invention includes a method for toothing one or more workpieces using a toothed finishing tool with an indeterminate cutting edge, the finishing tool having a basic barrel shape, wherein the finishing tool and the workpiece rotate in a roll-coupled manner, and the finishing tool moves along the width of the workpiece in a feed direction parallel to the axis of rotation of the workpiece in at least one tooth-cutting cut, thereby machining the workpiece across its width. It is proposed that, between the machining of two workpieces and / or between two tooth-cutting cuts at one workpiece and / or during one tooth-cutting cut, the contact path between the finishing tool and the workpiece is selectively shifted on the finishing tool to utilize additional areas of the tool surface by changing the angle of inclination between the finishing tool and the workpiece.

[0023] The inventors of this invention have recognized that, by changing the tilt angle, it is feasible to shift the contact path between the finishing tool and the workpiece on the finishing tool in a barrel-shaped finishing tool with an indeterminate cutting edge, without causing a change in the geometry of the workpiece machined by the finishing tool. This allows for the use of additional areas of the tool surface for finishing, thereby making better use of the tool surface. In particular, the contact path can be shifted to additional areas of the tool surface by changing the tilt angle, in which the tool surface is not yet worn or is worn less than in the area where the contact path extends before the shift.

[0024] Here, the contact path is the path on the tool that produces the final geometry that exists after the corresponding cut.

[0025] Thus, just as the shifting strategy is used in gear making of external teeth or with cylindrical tools by shifting the tool in the direction of the tool axis, the shifting strategy is now particularly feasible in gear making of internal teeth or with barrel-shaped tools by correspondingly changing the tilt angle.

[0026] According to one feasible design of the present invention, the workpiece can be an internally toothed workpiece. However, the present invention can also be used if the workpiece is an externally toothed workpiece.

[0027] The method for gear manufacturing according to the present invention can be used, in particular, for hard finishing of workpieces.

[0028] According to a feasible design of the present invention, within the scope of the invention, it can operate using the kinematic principles of generating scraping. Therefore, it preferably relates to a generating scraping method with an indeterminate cutting edge.

[0029] Therefore, according to a feasible design of the present invention, the relative motion between the workpiece and the finishing tool is achieved by means of the kinematic principle of generating scraping.

[0030] According to a feasible design of the present invention, the finishing tool is a generating scraping tool with an indeterminate cutting edge. Here, finishing tools as described in detail below are used in particular.

[0031] According to a feasible design of the present invention, the present invention may relate to a processing method having theoretical point contact.

[0032] The axial angle used in the method according to the invention may, for example, be in the range between 0 degrees and ± the workpiece helix angle (Schrägungswinkel), and / or in the range between 0 degrees and ±30°, preferably in the range between 0 degrees and ±25°.

[0033] The helix angle of the tool can, for example, be in the range between 0 degrees and ± the helix angle of the workpiece, and / or in the range between 0 degrees and ±30°, preferably in the range between 0 degrees and ±25°.

[0034] According to a feasible design of the invention, the finishing tool can be an unsalvageable tool, particularly a CBN tool with a preferably electroplated coating, or the contact path between the finishing tool and the workpiece can be shifted on the finishing tool without dressing the finishing tool during this period. Therefore, in both cases, the tilt angle is not changed to adapt the tilt angle to the tool geometry, but rather to better utilize the available surfaces of either unsalvageable or salvageable tools.

[0035] According to a feasible design of the present invention, the contact path between the finishing tool and the workpiece on the finishing tool is shifted according to a preset number of tooth cuttings and / or a preset shifting strategy.

[0036] According to a feasible design of the present invention, the tilt angle is changed without measuring the actual manufactured geometry of the workpiece or regardless of measuring the actual manufactured geometry of the workpiece. Therefore, instead of correcting the tilt angle to eliminate contour errors, the tilt angle is changed to move the contact path to another location, thereby making better use of the tool surface.

[0037] According to a feasible design of the present invention, the workpiece is produced with the same geometry after the contact path is shifted as before the shift. Therefore, the shift of the contact path is not used to correct errors in the workpiece geometry, but rather to better utilize the tool surface.

[0038] According to a feasible design of the invention, one or more additional motion axes of the gear-making machine are moved together with the change of tilt angle so that, despite the displacement of the contact path, the same geometry is produced on the workpiece as before the displacement of the contact path.

[0039] Here, one or more additional axes of motion of the gear cutting machine move in particular according to the magnitude of the change in tilt angle.

[0040] Preferably, when the tilt angle changes, the tracking axis intersection angle and / or axis spacing are tracked.

[0041] According to a feasible design of the present invention, the contact path between the finishing tool and the workpiece on the finishing tool is selectively shifted to utilize additional areas of the tool surface. This is achieved by changing the relative position between the finishing tool and the workpiece through alterations to the axial spacing, tilt angle, and axial intersection angle. Specifically, the tilt angle is selectively altered, and the axial spacing and axial intersection angle are adapted to the new tilt angle.

[0042] According to a feasible design of the invention, the contact path is repeatedly shifted to other regions of the tool surface by changing the tilt angle, wherein the shifting is preferably performed separately such that the tool surface in the other regions is not yet worn or is worn less than in the region extended by the contact path before the shift. Here, gear cutting is performed separately between changes in the tilt angle, and the tool surface in the region of the contact path is worn by the gear cutting.

[0043] According to a feasible design of the present invention, the contact path shifts at least 10% of the total tool width in one or more steps, preferably at least 20% of the total tool width.

[0044] According to a feasible design of the present invention, the tilt angle is changed by a total of at least 1 degree, preferably at least 2 degrees, and more preferably at least 4 degrees in one or more steps.

[0045] According to a feasible design of the present invention, material removal from the workpiece is performed in a single machining cut within a contact area that contacts the finishing tool. This contact area has an extension in the feed direction on the finishing tool, wherein a contact path is formed through the rearward end of the contact area in the feed direction. Therefore, the contact path defines the geometry on the workpiece produced by the finishing process, and conversely, material removal occurs within a contact area that expands relative to the contact path.

[0046] According to a feasible design of the invention, the barrel shape and / or tooth shape of the finishing tool and the lateral feed (Zustellung) relative to the workpiece are selected such that the width of the contact area between the workpiece and the finishing tool is at least 10% of the tool width, preferably at least 20% of the tool width, in which material removal on the workpiece is performed in a single machining cut in the contact area.

[0047] According to a feasible design of the invention, if the finishing cut (Schlicht-Schnitt) is performed as the next machining cut, the contact path is shifted in the feed direction so as to utilize the area of ​​the tool surface that has not yet been used for finishing.

[0048] According to a feasible design of the present invention, the finishing tool is clamped on the tool mandrel, which is accommodated in the tool receiving part on one side.

[0049] Here, the feed motion for machining is preferably performed by traction. This avoids collision between the finishing tool or tool spindle and the workpiece.

[0050] According to a feasible design of the invention, the finishing tool has two width regions with different grinding materials, particularly different coatings. Specifically, the first width region has a first grit and the second width region has a second grit, wherein these grits are different from each other, and one grit is particularly coarser than the other.

[0051] Thus, these two regions can be used for different machining steps, such as roughing and finishing. Furthermore, the tool division can be considered in light of the fact that material removal occurs on the extended contact surface, where a coarser grinding material is preferably used at least partially, and the resulting geometry is determined solely by the contact line, which preferably extends in a width region with a finer grinding material.

[0052] According to a feasible design of the present invention, a first width region is used for roughing and a second width region is used for finishing by tilting the finishing tool between roughing and finishing.

[0053] According to a feasible design of the present invention, the contact area during finishing is selected such that the portion of the contact area in front of the feed direction is in a first width region with a first grain size, and the contact path is in a second width region with a second grain size, wherein the first grain size is coarser than the second grain size.

[0054] According to a feasible design of the invention, the point of maximum radius of the finishing tool is offset relative to the center of the tool width, and the tool is divided into a first region and a second region with radii that decrease from said point, the first region and the second region having different widths. This allows the tilt angle to be kept in a region favorable for collision.

[0055] The difference in width between the two regions is preferably at least 5% of a smaller numerical value, and more preferably at least 10%.

[0056] Alternatively or additionally, the first region located in front of and / or away from the tool holder in the feed direction may have a greater width than the second region located behind and / or towards the tool holder in the feed direction.

[0057] According to a feasible design of the present invention, when machining a workpiece using a first contact area, the workpiece is operated at a numerically larger tilt angle than when machining a workpiece using a second contact area. The first contact area is adjacent to the end of the finishing tool that is forward and / or away from the tool holder in the feed direction, and the second contact area is adjacent to the end of the finishing tool that is rearward and / or toward the tool holder in the feed direction.

[0058] In the first variant, the contact path is positioned on the rearward side of the contact area in the feed direction. Therefore, in the case of the first contact area adjacent to the forward end of the finishing tool in the feed direction, the width of the contact area is spaced from the forward end of the finishing tool, allowing for operation at a smaller tilt angle. Conversely, in the case of the second contact area adjacent to the rearward end of the finishing tool, the contact path is directly next to the rearward end of the finishing tool, requiring a larger tilt angle. This consideration or approach is particularly applicable if the barrel shape of the finishing tool is symmetrical about the midplane of the finishing tool. In the second variant, the different tilt angles at the two ends of the tool are considered because, on the side facing the tool holder—that is, the side where the tool is clamped in the tool holder of the gear cutting machine—an interference profile exists due to the tool mandrel, which may hinder machining at a large tilt angle. Here, an asymmetrical barrel shape is preferably chosen to allow for different tilt angles.

[0059] The difference between the tilt angles is preferably at least 5% of a numerically smaller value, and more preferably at least 10%.

[0060] According to a feasible design of the present invention, roughing is performed using a gear-making process in which a finishing tool, as described above, moves through the workpiece in a feed direction parallel to the workpiece's axis of rotation during at least one gear-making cut, while finishing is performed by honing. The method described above is thus used only for roughing. Conversely, finishing can be performed by honing. The honing process can be performed according to known methods. Here, the honing tool is introduced into the workpiece, particularly radially. Here, oscillating motion can be performed in the axial direction of the workpiece and / or the tool.

[0061] According to a feasible design of the present invention, the first gear cutting and honing are performed by means of clamping the workpiece and / or the finishing tool in the same way.

[0062] According to a feasible design of the present invention, a first region and / or portion of a finishing tool is used for first gear cutting, and a second region and / or portion of a finishing tool is used for honing.

[0063] According to a feasible design of the present invention, the width convexity (Breitenballigkeit) of the second region and / or portion used for honing is less than the width convexity of the first region and / or portion.

[0064] According to a feasible design of the present invention, multiple identical workpieces are subjected to tooth-making processing, and / or multiple workpieces are provided with the same geometry through tooth-making processing.

[0065] According to a feasible design of the present invention, the contact path is shifted multiple times.

[0066] Furthermore, the present invention includes a finishing tool for the method described above, namely a toothed tool having a basic barrel shape and an indeterminate cutting edge, the tool being designed for use in the method according to the present invention.

[0067] Within the scope of this invention, the basic barrel shape specifically means that the radius of the base defined by the finishing tool decreases laterally in the direction of the tool's rotation axis, originating from the point with the largest radius. Here, the radius preferably decreases continuously. The tool can, in particular, be implemented with a width convexity.

[0068] The finishing tool has teeth that extend in the width direction on the circumferential surface of the finishing tool. These teeth can be straight or helical.

[0069] According to a feasible design of the invention, the finishing tool has first and second width regions, areas, and / or portions with different grinding materials and / or different widths and / or different width convexities. Here, the finishing tool and / or said regions are specifically designed as described above in relation to the method.

[0070] According to a feasible design of the present invention, the finishing tool is designed as a generating scraping tool with an indeterminate cutting edge.

[0071] According to a feasible design of the invention, the profile of the tool has the shape of a generating scraper cutting edge for each tooth at each width position in a cross-sectional plane passing through the point on the outer diameter. Here, the profile is specifically designed such that the generating scraper defining the profile is designed for the corresponding outer diameter and positioned at a selected effective axis angle and can be used obliquely at an angle δ, which corresponds exactly to the derivative of the outer diameter direction at the corresponding width position.

[0072] Here, the profile-defining plane corresponds to the plane or cutting surface developed by the cutting edge of the generating scraper that defines the profile. Therefore, the orientation of the profile-defining plane depends on the rake angle (Spanwinkel) and step angle selected for the corresponding generating scraper.

[0073] Here, the front angle and step angle can be designed according to different strategies.

[0074] In a feasible design, a step angle is selected within a range of + / -3° around the helix angle of the tool on the corresponding tool width, and / or a rake angle is selected within a range of + / -3° around the inclination angle on the corresponding tool width, such that the profile on the finishing tool is substantially defined in the normal section of its teeth.

[0075] However, other step angles and / or front angles may also be considered.

[0076] In a feasible design, a step angle of 0° and a rake angle of 0° are chosen so that the profile on the finishing tool is defined in the end section.

[0077] However, there is no defined cutting edge on a finishing tool; more precisely, the surface geometry is defined by the theoretical arrangement of these cutting edges in the tool width direction as a continuous surface with indeterminate cutting edges. This surface is formed on the tool by the envelope of particles on the tool's surface.

[0078] Furthermore, the present invention includes a gear-making machine having a workpiece receiving portion rotatably driven about a first rotational axis and a tool receiving portion rotatably driven about a second rotational axis, wherein the tool receiving portion and the workpiece receiving portion are movable relative to each other via a motion axis of the gear-making machine, and the gear-making machine has a control device programmed to manipulate the motion axis of the gear-making machine such that the gear-making machine performs the method according to the invention as described above. Preferably, the gear-making machine performs the method automatically.

[0079] Furthermore, the present invention includes a computer program comprising instructions that, when executed on the control device of the gear-making machine as described above, manipulate the motion axis of the gear-making machine to cause the gear-making machine to perform the method according to the present invention as described above.

[0080] The control device particularly features a microcontroller and non-volatile memory, on which a computer program is stored, the instructions of which are processed on the microcontroller. The control device is connected to and operates the drive mechanism of the gear-making machine's motion axis.

[0081] The drive unit of the gear cutting machine is preferably an NC drive unit. Attached Figure Description

[0082] The present invention will now be described in detail with reference to embodiments and accompanying drawings.

[0083] This is shown here:

[0084] Figure 1A A schematic diagram illustrating the method according to the invention and the tooth-making machine according to the invention is shown.

[0085] Figure 1B A perspective view of one embodiment of the tooth-making machine according to the present invention is shown.

[0086] Figure 2 This illustrates the operation using a first contact path and a second contact path within the scope of one embodiment of the method according to the invention.

[0087] Figure 3 The diagram illustrates the principle of two finishing tools according to the present invention, with the contact areas belonging to the contact path drawn on each tool.

[0088] Figure 4 A schematic diagram illustrating the principle of a finishing tool according to the invention, having first and second width regions using different grinding materials, is shown.

[0089] Figure 5 The invention illustrates a finishing tool with a symmetrical barrel shape and a finishing tool with an asymmetrical barrel shape, thus showing two regions with different widths.

[0090] Figure 6A and Figure 6B The theoretical cutting edge orientation of a generating scraper is shown, defining the surface geometry of the finishing tool via the cutting edge for different tool width positions in two embodiments, wherein in Figure 6A The middle step angle and the front angle are zero and in Figure 6B The middle step angle corresponds to the helix angle.

[0091] Figure 7 This illustrates the theoretical direction of the cutting edge of a generating scraper, through which the surface geometry of the finishing tool is defined by the rake angle of the theoretical cutting edge adapted to the tilt angle. Detailed Implementation

[0092] Figure 1A A schematic diagram of a tooth-making machine 100 according to the present invention is shown.

[0093] The gear-making machine 100 has a workpiece receiving portion 50 that is rotatably driven about a first rotational axis C2 and a tool receiving portion 40 that is rotatably driven about a second rotational axis C1. The tool receiving portion 40 can be particularly implemented as a tool holder, in which the tool is clamped on one side. The tool receiving portion 40 and the workpiece receiving portion 50 can move relative to each other via the motion axis of the gear-making machine. Here, the axis arrangement preferably corresponds to a generating scraper and / or a honing machine.

[0094] Figure 1B An embodiment of a gear-making machine and a motion axis available on the gear-making machine are shown.

[0095] Here, a motion axis Z1 is specifically provided, through which the tool receiving portion 40 can move relative to the workpiece receiving portion 50, allowing the tool 20 to move through the workpiece in the direction of the rotation axis C2 of the workpiece receiving portion. For this purpose, the motion axis Z1 preferably extends parallel to the rotation axis C2. Furthermore, a motion axis X1 may be provided, via which the tool 20 is laterally fed into the workpiece 30. The motion axis X1 is preferably perpendicular to the rotation axis C2. The motion axis V1 allows movement in a plane perpendicular to the X1 axis and / or movement in a direction perpendicular to the rotation axis C1. The motion axes X1, V1, and Z1 are preferably linear axes.

[0096] In addition, a pivot axis A1 is provided, which extends parallel to the X1 axis and perpendicular to the C1 axis, and the tool receiving part 40 can rotate via the pivot axis A1.

[0097] According to the design, the A1 axis can rotate the machining head, which includes the V1 axis and the tool holder 40, or the A1 axis can be mounted on a slider that can move via the V1 axis and only rotate the tool holder 40. In the latter case, the V1 axis is perpendicular to the Z1 axis. In the first case, the V1 axis can rotate via the A1 axis in a plane perpendicular to the X1 axis and preferably perpendicular to the C1 axis, that is, the V1 axis can move the C1 axis parallel to it.

[0098] The tilt angle and axis intersection angle between axes C2 and C1 can be set via axis A1, in conjunction with axes X1 and V1.

[0099] If the tool is positioned laterally next to or inside the workpiece, such that the rotation axes C2 and C1 of the workpiece and the tool are in a plane perpendicular to axis A1, the tilt angle can be set by pivoting axis A1.

[0100] Conversely, if the tool is in front of or in the middle of the workpiece, such that the common perpendicular of the rotation axes C2 and C1 of the workpiece and the tool extends parallel to axis A1, then the axis angle is changed by pivoting axis A1.

[0101] In the intermediate position, changing the A1 axis alters not only the axis intersection angle but also the tilt angle. However, the structural design of the motion axis is not limited to the design described above. This invention can also be implemented using other designs for the motion axis.

[0102] Furthermore, a control device 200 is provided, which is programmed to execute the method according to the invention. The motion axis preferably has an NC drive device, which is controlled by the control device.

[0103] exist Figure 2The concept of the method according to the invention shown here lies in implementing the cutting tool (20) such that the contact path (24, 24') between the cutting tool (1) and the workpiece (2) can be displaced. This is achieved by changing the inclination angle of the barrel-shaped or convex cutting tool (20) with a geometrically indeterminate cutting edge, as in Figure 2 As shown in the diagram.

[0104] Because machining is typically eccentric, multiple axes are used in combination for this purpose in practice. Additionally, the axis spacing and axis intersection are tracked.

[0105] In particular, axis A1 is used to pivot tool 20, while the positions of other axes Y1, X1, C1, Z1, and C2 are adjusted so that the tool is still engaged with the workpiece, producing the desired tilt angle and axis intersection angle, and producing the same geometry on the workpiece by means of the new contact path as by means of the old contact path.

[0106] By shifting the contact path (24) to (24'), a new, unused contact path (24') can be engaged with the workpiece after the standard path endpoint of the first contact path (24) is reached.

[0107] The already used contact path (24) moves to the contact surface (23, 23') where material removal is not decisive in terms of quality, said contact surface in Figure 3 As shown in the figure. The process of engaging the unused contact path (23') can be repeated multiple times until the upper edge of the tool (20, 20') is reached.

[0108] Here, Figure 2 The last possible displacement position of the contact path (24) from the high point of the convexity to the upper edge of the tool is shown. Additional displacement positions of the contact path are preferably used on the path from the contact path (24) to the contact path (24').

[0109] Here, the machining process preferably corresponds to generating scraping in kinematics, but is carried out with the aid of a finishing tool having an indeterminate cutting edge. Therefore, it preferably involves generating scraping with an indeterminate cutting edge. Thus, it works particularly with, for example, a significantly smaller axis angle compared to generating grinding.

[0110] To determine the required geometry of the cutting tool, according to a feasible design according to the invention, the maximum outer diameter at the cutting tool location is first determined, as well as the axial angle at which the cutting tool should operate. Here, the axial angle is referred to as the angle when the intersecting axes of rotation of the workpiece and the cutting tool are projected along the common perpendicular of these axes of rotation, and this angle also corresponds to the effective axial angle when machining the teeth using the contact trajectory at the maximum outer diameter of the cutting tool location.

[0111] From the aforementioned axial arrangement, an ellipse is derived from the cylindrical section formed by the workpiece tooth root cylinder via a plane given by the common perpendicular vector through the rotation axis of the tool and the stretching vector. The minor semi-axis of this ellipse corresponds to the maximum outer diameter at the selected tool. The ellipse gives the boundary of the outer diameter at the tool's width on the tool, i.e., the position given in the direction of the tool's rotation axis. Starting from the maximum diameter, it must be below this boundary in both directions in a strictly monotonically decreasing manner with monotonically decreasing derivatives, in order to obtain space for displacement—in practice, for example, this can be implemented by modifying a parabola as the cylindrical section.

[0112] Subsequently, for each width position on the tool, the cutting edge of the scraping tool (e.g., using publicly available software such as SkivAll) can be designed such that the generating scraping tool is designed for the corresponding outer diameter and positioned with a selected effective axis intersection angle and tilted with an inclination angle δ, which corresponds exactly to the derivative of the outer diameter direction at the corresponding height, so that the tip of the tool can be tangentially located at the root of the workpiece to be manufactured.

[0113] Then, the cutting edge and the tool are joined together such that the helix angle at the diameter of the tool corresponds at each width position of the tool to the difference between the effective axis intersection angle and the helix angle of the workpiece, wherein the diameter of the tool manufactures an arbitrary but fixed diameter of the workpiece.

[0114] Figure 6 and Figure 7 The selected cutting edge for defining the tool is shown, which serves as a tooth of the tool according to its position in the tool width, which extends from top to bottom.

[0115] Here, for each position in the tool width, a theoretical generating scraper is defined by the maximum outer diameter that exists there according to the selected outer diameter direction, and the cutting edge of the generating scraper then defines the surface of the tool at the width position.

[0116] Here, the orientation of the cutting edge can be selected in the same way, thereby defining the geometry of the tool, as is done in conventional generating scraping tools with defined cutting edges by selecting the step angle and rake angle.

[0117] With the step angle and rake angle both zero, the geometry of the tool is defined for all teeth in a plane perpendicular to the tool's axis of rotation, as shown in... Figure 6A As shown in the diagram for the teeth.

[0118] Conversely, when the step angle and / or rake angle are not zero, the geometry of the tool is defined for each tooth in a plane corresponding to that tooth at the corresponding tool width. Here, this plane (in which the cutting edge of the theoretical generating scraper lies, and thus the tooth profile is defined) can rotate for each tooth about an axis extending from the tooth tip to the tool's rotation axis, corresponding to the step angle of the cutting edge, and simultaneously, this axis can be inclined about a plane perpendicular to the rotation axis, corresponding to the rake angle of the cutting edge.

[0119] Especially common in generating scraping tools is the selection of a step angle that substantially corresponds to the helix angle of the tool, such that the cutting edge extends in a plane perpendicular to the tooth's extension and thus normal to the tooth surface, as is the case in... Figure 6B As shown in the diagram.

[0120] Here, the step angle can be kept constant over the tool width. Instead, the rake angle can be tracked by means of a tilt angle, which is defined about the tool's axis of rotation and thus independent of its positioning relative to the workpiece, as is the case in... Figure 7 As shown, so that the same meshing relationship at the workpiece is thus achieved along the plane defining the contour, regardless of the tilt angle.

[0121] However, the examination revealed that the surface geometry of the tool, as defined by the invention, is largely independent of the plane defining the profile, and thus largely independent of the step angle and rake angle.

[0122] The strictly monotonic direction of the outer diameter can be chosen such that the expected lateral feed over the defined width region is achieved as a deviation from the enclosing ellipse, thus allowing the tool to remove material in a single cut using the expected lateral feed over the defined width region. In practice, this is more precisely defined on the tooth surface, whereby the expected lateral feed is calculated from the machining allowance to be removed on the tooth surface via the profile angle, so that the machining allowance to be removed is then removed over the defined width region. Therefore, the width region for material removal at the tool can be selected by choosing the direction of the outer diameter—selecting a smaller region through a stronger deviation from the ellipse—and this can be particularly varied at different width positions of the tool.

[0123] Furthermore, typically, instead of finishing the entire tooth, only the working tooth surface or the involute portion within the shape circle is finished, allowing a free cutting portion to be introduced during soft machining via a tool with raised sections, thus preserving manufacturing allowances on the tooth surface. The tooth with corrected top and root clearances is then used in place of the desired final geometry for tool design.

[0124] The axial angle used in the method according to the invention may, for example, be in the range between 0 degrees and ± the helix angle of the workpiece, and / or in the range between 0 degrees and ±30°, especially in the range between 0 degrees and ±25°.

[0125] Within the scope of this invention, the tilt angle is varied to form a new contact path with the workpiece. Here, the tilt angle can vary within a range that typically extends from a maximum of -30° to a maximum of +30°, but is generally extended from a maximum of -15° to a maximum of +15°.

[0126] Preferably, the change in the tool's tilt angle is greater than 1° in total within the scope of the method according to the invention, preferably greater than 4°, and in feasible applications, greater than 10° or greater than 20°. Here, the change in tilt angle is typically performed in multiple steps, with the contact path shifted by means of these multiple steps, so as to process one or more workpieces by means of the new contact path.

[0127] Here, the shaft intersection angle tracks the tilt angle so that the meshing relationship remains substantially the same or the effective shaft intersection angle is set to the desired value.

[0128] Here, the change in the axis angle corresponds on the order of magnitude to the change in the tilt angle.

[0129] Conversely, the effective axis angle can remain the same throughout the machining process. However, this causes problems in tool design, where the position of the tooth face in truly straight-toothed tools varies slightly across the tool width.

[0130] Therefore, in a feasible design of the present invention, the effective axis angle can also be changed in the tool width to compensate for the effect. However, in a feasible design, the change in the effective axis angle is less than + / - 1 degree.

[0131] Therefore, tracking the axis intersection angle across the tool width is necessary to adapt to changing tilt angles and, if necessary, to set the effective axis intersection angle for the change.

[0132] The shifting of the contact path (24, 24') can be performed not only between individual cuts but also during a single cut. The cutting is performed by means of the tool (30) axially passing through the teeth of the workpiece (20).

[0133] By using a tool modified with convex spherical shapes of varying strengths (20 / 20'), it is possible to achieve the following: Figure 3The contact area (23 / 23') between the tool (20 / 20') and the workpiece (30) is increased or decreased as shown. This allows material removal to be distributed across the corresponding surfaces. Here, the tool shown on the right has a greater convexity than the tool shown on the left, resulting in a smaller contact area 23' for the same transverse feed relative to the workpiece or the same material removal.

[0134] Here, the convexity and material removal by machining can be set such that the width of the contact surfaces 23, 23' is greater than 5% of the total width of the tool, preferably greater than 10% of the total width of the tool. Significantly larger widths are also possible. Therefore, the width of the contact surfaces can be greater than 20%, 30%, 40%, or 50% of the total width of the tool. Preferably, the width is less than 70% of the total width of the tool. According to the invention, the area not occupied by the contact surfaces can then be used to move the contact paths 24, 24'. The contact paths 24, 24' are the boundary lines of the contact surfaces rearward in the feed direction.

[0135] By tilting the cutter (20, 20'), the contact surface (23 / 23') can be shifted, thereby shifting the contact path (24 / 24').

[0136] As already described above, if the tool (20 / 20') moves through the workpiece from top to bottom and not in reverse, the contact path (24 / 24') is the upper boundary of the contact surface (23 / 23'). This ideally allows for machining with a single cut, in which the main material removal (roughing) is performed through the surface (23 / 23') and the contact path (24 / 24') produces the final geometry of the workpiece (finishing).

[0137] In this scenario, once the currently used area wears out, the contact path can be moved to an unused area.

[0138] However, there are also several other shifting strategies, namely, strategies for using the movement of the contact path to optimally utilize the tool width. In this case, machining can also be performed in at least two separate cuts, i.e., at least one roughing cut and one finishing cut.

[0139] The following variants are particularly worth considering:

[0140] - Roughing / finishing is performed in the new area. Then, the area is shifted so that the currently finished area slides into the roughing area.

[0141] - Roughing / finishing is performed in separate areas by shifting between cuts (pivoting to new areas as needed).

[0142] - Segment shift

[0143] In addition to different shifting strategies, it is also possible to use different grinding materials and, in particular, coatings for the roughing and finishing areas, different implementations of the cutting tools (adjusted / unadjusted), and / or, according to the invention, to perform roughing by axial movement through the workpiece and to perform finishing radially by honing.

[0144] The processing strategy in particular can utilize tools from areas with different overburden layers, as is the case in... Figure 4 As shown, for example, the region 25 in the front of the feed direction is coated with a coarser grain and used for roughing, while the portion 6 in the rear of the feed direction is coated with finer grains.

[0145] Therefore, the intermediate region 50 can be finished with fine grains and roughed with coarse grains in a single cut, or, however, by the tilting as described above, each region itself is approached on different contact paths, thus wearing uniformly. This division can be achieved in a single tool or by assembling two tools.

[0146] According to the invention, the cutting tools can also be used in a uniformly layered manner so that either roughing and finishing are performed by means of different cutting tools, or roughing is performed first by means of an adjusted cutting strategy and then finishing of the surface is performed by means of smaller lateral feed, slower feed, or the reverse of roughing is performed.

[0147] Because material is always removed in the area ahead of contact path 24 in the machining direction, but without contributing to the final geometry, a contact trajectory is derived that is at the forefront in the feed direction. Below this contact trajectory, the contact path at the corresponding tool width can never be approached. However, at the rear end, it is theoretically possible to shift until the end of the tool, resulting in a steeper tilt angle in this symmetrical implementation of the tool, as this is in Figure 5 As shown on the left side. This is the following side in the common machining direction undertaken by scraping, where the tool spindle 22 for the tool extends on said side, and the tool is clamped in a tool holder on said side, as in... Figure 5 As shown on the left side, 50 is unfavorable due to the collision.

[0148] The problem can be explained in two ways:

[0149] 1. The barrel shape or width convexity at the tool is applied asymmetrically across the tool width, such as in... Figure 5As shown on the right side, the high point 27 on the tooth is positioned relative to the center in the feed direction, rearward and / or closer to the tool holder, at the tool location, so that the tilt angle for the accessible position is positioned away from the workpiece. Consequently, region 28 has a larger width than region 29, in which the radius decreases from the high point 27 in the feed direction and / or away from the tool holder, while in region 29, the tool radius decreases from the high point 27 in the opposite direction to the feed direction and / or towards the tool holder. This can be achieved such that the tilt angle for the accessible position is symmetrical, or further as in... Figure 5 As shown on the right side of the image. This is primarily because collision can be meaningful, but it can also be used for other purposes.

[0150] 2. The process is performed in a traction manner, thereby making the area 29 pointing towards the tool holder inaccessible to the final profile, thus eliminating unfavorable tilt angles. Additionally, the tool can be asymmetrically positioned in width, as in point 1. With symmetrical modification in width, traction machining particularly reduces the overtravel distance because the highest contact path to be approached at the tool is therefore further away from the end of the tool pointing towards the tool holder. This can be used particularly to reduce the clamping width, or, in the case of teeth sensitive to overtravel, to provide another possibility for reducing overtravel in tool design. This possibility exists in addition to options known from scraping: reducing the tilt angle, reducing the outer diameter (both of which have disadvantages), but not in traction machining. In traction machining, the tool passes through the workpiece feed, such that the tool holder is positioned in front of the tool in the feed direction, whereas in push-back machining it is positioned behind the tool.

[0151] The method according to the invention can be used in particular for machining internal teeth, and can achieve significantly better utilization of the cutting tool and thus reduce costs compared to known methods.

[0152] The method according to the invention can also be used for external teeth in the exact same manner. Here, although other effective methods have been provided in many cases, the method according to the invention can be particularly advantageous when methods such as generating grinding cannot be used due to limited overtravel or impact-sensitive teeth. Here, the method according to the invention essentially has the same application area as generating scraping performed with a tool having a defined cutting edge.

[0153] The method according to the invention can be used to perform complete hard finishing on a workpiece on a machine. It is also conceivable to use the method for superfinishing or polishing. In these cases, the tool is implemented using the same material as in finishing or polishing tools. Here, the tool can in particular be made of a flexible material or coated with such a flexible material.

Claims

1. A method for toothing, particularly hard finishing, one or more workpieces using a toothed finishing tool with an indeterminate cutting edge, said finishing tool having a basic barrel shape. The finishing tool and the workpiece rotate in a rolling coupling with each other, and the finishing tool moves in a feed direction parallel to the rotation axis of the workpiece in at least one tooth-cutting operation to machine the workpiece across its width. Its features are, Between the machining of two workpieces and / or between two tooth cutting operations on a workpiece and / or during a single tooth cutting operation, the contact path between the finishing tool and the workpiece is selectively shifted on the finishing tool to utilize additional areas of the tool surface by changing the tilt angle between the finishing tool and the workpiece.

2. The method according to claim 1, wherein the relative movement of the workpiece and the finishing tool is performed by means of the kinematics principle of generating scraping, and / or wherein the finishing tool is a generating scraping tool with an indeterminate cutting edge, and / or wherein the finishing tool is an unskillable tool, particularly preferably an electroplated CBN tool, or wherein the contact path between the finishing tool and the workpiece on the finishing tool is displaced, during which the finishing tool is not dressed.

3. The method according to claim 1 or 2, wherein the contact path between the finishing tool and the workpiece on the finishing tool is shifted according to a preset number of tooth cuttings and / or a preset shifting strategy, and / or wherein the tilt angle is changed without measuring the actual manufactured geometry of the workpiece or independent of measuring the actual manufactured geometry of the workpiece.

4. The method according to any one of the preceding claims, wherein the contact path is repeatedly shifted to other regions of the tool surface by changing the tilt angle, wherein the shift is preferably performed such that the tool surface is not yet worn or is less worn in the other regions than in the regions to which the contact path extends before the shift, and / or wherein the contact path shifts at least 10% of the total tool width, preferably at least 20% of the total tool width, in one or more steps.

5. The method according to any one of the preceding claims, wherein the material removal on the workpiece is performed in a single machining cut within a contact area in contact with the finishing tool, the contact area having an extension in the feed direction on the finishing tool, wherein the contact path is formed through the rearward end of the contact area in the feed direction.

6. The method according to any one of the preceding claims, wherein the barrel shape and / or tooth shape of the finishing tool and the transverse feed relative to the workpiece are selected such that the width of the contact area between the workpiece and the finishing tool is at least 10% of the tool width, preferably at least 20% of the tool width, and material removal from the workpiece is performed in the contact area in a single machining cut.

7. The method according to any one of the preceding claims, wherein the finishing tool is clamped on a tool mandrel, the tool mandrel being received in a tool receiving portion on one side, wherein the feed motion for machining is preferably performed in a traction manner.

8. The method according to any one of the preceding claims, wherein the finishing tool has two width regions, the two width regions having different grinding materials, and in particular having different coatings.

9. The method of claim 8, wherein a first width region is used for roughing and a second width region is used for finishing by tilting the finishing tool between roughing and finishing, and / or wherein the contact region during grinding is selected such that a portion of the contact region forward in the feed direction is in the first width region having a first grain size, and the contact path is in the second width region having a second grain size, wherein the first grain size is coarser than the second grain size.

10. The method according to any one of the preceding claims, wherein the point of maximum radius of the finishing tool is offset relative to the center of the tool width, and the tool is divided into a first region and a second region having radii that become progressively smaller from the point, the first region and the second region having different widths, wherein the difference is preferably at least 5% of a numerically smaller value, and / or wherein preferably, the first region, which is positioned forward and / or away from the tool holder in the feed direction, has a larger width than the second region, which is positioned backward and / or towards the tool holder in the feed direction. Preferably, when machining the workpiece using the first contact area, the workpiece is operated at a numerically larger tilt angle than when machining the workpiece using the second contact area. The first contact area is adjacent to the front end of the finishing tool in the feed direction and / or away from the tool holder, and the second contact area is adjacent to the rear end of the finishing tool in the feed direction and / or towards the tool holder. The difference is preferably at least 5% of a numerically smaller value.

11. The method according to any one of the preceding claims, wherein a gear-making process is used for roughing, in which the finishing tool moves in a feed direction parallel to the axis of rotation of the workpiece in at least one gear-making cut, and finishing is performed by honing, wherein the first gear-making process and the honing are preferably performed by means of the same clamping of the workpiece and / or the finishing tool. More preferably, a first region and / or portion of the finishing tool is used for the first tooth-making process, and a second region and / or portion of the finishing tool is used for the honing process, wherein preferably the width convexity of the second region and / or portion used for the honing process is less than the width convexity of the first region and / or portion.

12. The method according to any one of the preceding claims, wherein a plurality of identical workpieces are subjected to tooth-making, and / or the plurality of workpieces are provided with the same geometry by the tooth-making, wherein the contact path is preferably shifted multiple times.

13. A finishing tool for the method according to any one of the preceding claims, particularly a finishing tool having first and second width regions, regions and / or portions having different grinding materials and / or different widths and / or different width convexities, and / or a finishing tool that is a generating scraper with an indeterminate cutting edge and / or the profile of the finishing tool has the shape of the cutting edge of a generating scraper for each tooth at each width position in a cross-section plane passing through a point on the outer diameter, wherein the profile is preferably designed such that the generating scraper defining the profile is designed for the corresponding outer diameter and positioned at a selected effective axis intersection angle and can be used obliquely at an angle δ, the angle corresponding exactly to the derivative of the outer diameter direction at the corresponding width position.

14. A gear-making machine having a workpiece receiving portion rotatably driven about a first rotational axis and a tool receiving portion rotatably driven about a second rotational axis, wherein the tool receiving portion and the workpiece receiving portion are movable relative to each other via a motion axis of the gear-making machine, and the gear-making machine having a control device programmed to manipulate the motion axis of the gear-making machine such that the gear-making machine performs the method according to any one of the preceding claims.

15. A computer program having instructions that, when executed on a control device for a gear-making machine according to claim 14, control the motion axis of the gear-making machine to cause the gear-making machine to perform the method according to any one of the preceding claims.

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